CN108731825B

CN108731825B - Terahertz wave wavelength detection method

Info

Publication number: CN108731825B
Application number: CN201710259273.1A
Authority: CN
Inventors: 张凌; 柳鹏; 吴扬; 范守善
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2017-04-20
Filing date: 2017-04-20
Publication date: 2020-04-14
Anticipated expiration: 2037-04-20
Also published as: CN108731825A; TW201840079A; TWI619321B

Abstract

The invention relates to a terahertz wave wavelength detection method, which comprises the following steps: directly making a detected terahertz wave incident on the terahertz wave receiving device, the terahertz wave receiving device detecting first intensity data of the detected terahertz wave; enabling the detected terahertz waves to penetrate through a carbon nanotube structure and then to be incident on the terahertz wave receiving device, wherein the terahertz wave receiving device detects second intensity data of the detected terahertz waves; calculating a transmittance curve of the detected terahertz waves according to the second intensity data and the first intensity data; and comparing standard data of the transmittance curve with the standard data to obtain the wavelength range of the detected terahertz waves, wherein the standard data comprises data of the relationship between the transmittance of the terahertz waves to the carbon nanotube structure and the wave number.

Description

Terahertz wave wavelength detection method

Technical Field

The invention relates to the technical field of terahertz wave detection, modulation and application.

Background

Terahertz waves generally refer to electromagnetic waves with the frequency of 0.1 THz-10 THz and the wavelength of 30 mu m-3 mm, the wave band of the terahertz waves is between microwave and infrared light, and the terahertz waves belong to far infrared wave bands. Scientists have had very limited knowledge of the nature of this band of electromagnetic radiation due to the lack of efficient production methods and detection means.

In recent ten years, due to the rapid development of an ultrafast laser technology, a stable and reliable excitation light source is provided for the generation of terahertz waves, so that the generation and application of terahertz waves are developed vigorously. However, since the terahertz source has low emission power and relatively high thermal background noise, a highly sensitive detection means is required to detect the terahertz signal. At present, people have less knowledge on the performance of terahertz waves. Therefore, how to detect, modulate and apply terahertz waves becomes a hot point of research.

Disclosure of Invention

The inventor of the application researches and discovers that the transmittance of the terahertz waves can be adjusted through the carbon nanotube structure, namely, the transmittance of the terahertz waves is in a wave crest and wave trough alternating shape along with wave numbers or wavelengths. Moreover, the shape of the wave crest and the wave trough can be further adjusted by adjusting the temperature of the carbon nano tube structure or adjusting the included angle between the extending direction of the carbon nano tube in the carbon nano tube structure and the polarization direction of the terahertz wave. In view of the above, the present invention provides a terahertz wave transmitting device, a terahertz wave communication device and a terahertz wave wavelength detecting device.

A terahertz wave wavelength detection method comprises the following steps: directly making a detected terahertz wave incident on the terahertz wave receiving device, the terahertz wave receiving device detecting first intensity data of the detected terahertz wave; enabling the detected terahertz waves to penetrate through a carbon nanotube structure and then to be incident on the terahertz wave receiving device, wherein the terahertz wave receiving device detects second intensity data of the detected terahertz waves; calculating a transmittance curve of the detected terahertz waves according to the second intensity data and the first intensity data; and comparing standard data of the transmittance curve with the standard data to obtain the wavelength range of the detected terahertz waves, wherein the standard data comprises data of the relationship between the transmittance of the terahertz waves to the carbon nanotube structure and the wave number.

In the terahertz wave wavelength detection method, the carbon nanotube structure includes a carbon nanotube film, the carbon nanotube film includes a plurality of carbon nanotube bundles connected end to end by van der waals force, and each carbon nanotube bundle includes a plurality of carbon nanotubes parallel to each other.

In the terahertz wave wavelength detection method, the surfaces of the plurality of carbon nanotubes are coated with the metal conductive layer.

In the terahertz wavelength detection method, the edge of the carbon nanotube structure is fixed on a support frame, and the middle part of the carbon nanotube structure is suspended through the support frame.

The method for detecting the wavelength of the terahertz wave further comprises the following steps of enabling the detected terahertz wave to transmit through the carbon nanotube structure: changing an included angle between the extending direction of the carbon nano tube in the carbon nano tube structure and the polarization direction of the terahertz wave; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the included angle between the extension direction of the carbon nanotube in the carbon nanotube structure and the polarization direction of the terahertz waves.

In the method for detecting a terahertz wave wavelength, the method for changing the included angle between the extending direction of the carbon nanotube in the carbon nanotube structure and the polarization direction of the terahertz wave is to rotate the carbon nanotube structure.

The method for detecting the wavelength of the terahertz wave further comprises the following steps of enabling the detected terahertz wave to transmit through the carbon nanotube structure: heating the carbon nanotube structure and measuring the temperature of the carbon nanotube structure; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the temperature of the carbon nanotube structure.

The method for detecting the wavelength of the terahertz wave further comprises the following steps of enabling the detected terahertz wave to transmit through the carbon nanotube structure: applying a voltage across the carbon nanotube structure; the standard data includes data of the transmittance of the terahertz wave to the carbon nanotube structure as a function of the wave number and the voltage applied to the carbon nanotube structure.

The method for detecting the wavelength of the terahertz wave further comprises the following steps of enabling the detected terahertz wave to transmit through the carbon nanotube structure: rotating and heating the carbon nanotube structure; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the temperature and the rotation angle of the carbon nanotube structure.

In the terahertz wavelength detection method, the carbon nanotube structure is suspended in a vacuum container.

Compared with the prior art, the terahertz wave wavelength detection method provided by the invention has the advantages that the terahertz wave wavelength is detected through the modulation rule of the carbon nano tube structure on the terahertz wave, the structure is simple, and the detection method is reliable.

Drawings

Fig. 1 is a schematic structural diagram of a terahertz wave transmitting device provided in embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of a modulation device of a terahertz wave transmitting device provided in embodiment 1 of the present invention.

Fig. 3 is a scanning electron micrograph of a drawn carbon nanotube film used in example 1 of the present invention.

FIG. 4 is a scanning electron micrograph of a non-twisted carbon nanotube wire used in example 1 of the present invention.

FIG. 5 is a scanning electron micrograph of a twisted carbon nanotube wire used in example 1 of the present invention.

Fig. 6 shows the results of the transmittance test of the drawn carbon nanotube film in the same direction for the terahertz waves in the far infrared band in example 1 of the present invention.

Fig. 7 is a result of a transmittance test of a carbon nanotube drawn film arranged in the same direction for terahertz waves in mid-infrared band in embodiment 1 of the present invention.

Fig. 8 is a result of a transmittance test of the carbon nanotube drawn film crossing the set in embodiment 1 of the present invention for terahertz waves in the far infrared band.

Fig. 9 shows the results of the transmittance test of the carbon nanotube drawn film coated with the prefabricated layer in the same direction for the terahertz waves in the far infrared band in example 2 of the present invention.

Fig. 10 is a result of a transmittance test of a carbon nanotube drawn film coated with a prefabricated layer disposed in the same direction for terahertz waves in mid-infrared band in embodiment 2 of the present invention.

Fig. 11 is a schematic structural diagram of a terahertz wave transmitting device provided in embodiment 3 of the present invention.

Fig. 12 is a schematic structural view of a modulation device and a rotation device of a terahertz wave transmitting device provided in embodiment 3 of the present invention.

Fig. 13 is a result of a transmittance test of the carbon nanotube drawn film arranged in the same direction on the terahertz wave of the far infrared band after rotating by 15 degrees each time in embodiment 3 of the present invention.

Fig. 14 shows the results of the transmittance test of the carbon nanotube drawn film in the same direction for the terahertz waves in the far infrared band after the drawn film is rotated by 0 degree and 90 degrees in embodiment 3 of the present invention.

Fig. 15 shows the results of the transmittance test of the carbon nanotube drawn film in the same direction for the terahertz waves in the far infrared band after the drawn film is rotated by 60 degrees and 150 degrees in embodiment 3 of the present invention.

Fig. 16 is a result of a transmittance test of the carbon nanotube drawn film arranged in the same direction on a terahertz wave in a far infrared band after being rotated by 0 degree and 180 degrees in embodiment 3 of the present invention.

Fig. 17 is a schematic structural diagram of a terahertz wave transmitting device provided in embodiment 4 of the present invention.

Fig. 18 is a schematic structural view of a modulation device and a heating device of a terahertz wave transmitting device provided in embodiment 4 of the present invention.

Fig. 19 is a cross-sectional view taken along line S-S of fig. 18.

Fig. 20 is a schematic structural view of another heating apparatus of the terahertz wave transmitting apparatus provided in embodiment 4 of the present invention.

Fig. 21 is a result of a transmittance test of terahertz waves in the mid-infrared band after heating single-layer carbon nanotube drawn films arranged in the same direction by applying different voltages in embodiment 4 of the present invention.

Fig. 22 is a result of a transmittance test of a single-layer carbon nanotube drawn film arranged in the same direction on a terahertz wave in a far infrared band after being heated by applying different voltages in embodiment 4 of the present invention.

Fig. 23 is a result of a transmittance test of a terahertz wave in a far infrared band after a double-layered carbon nanotube drawn film arranged in the same direction is heated by applying different voltages in embodiment 4 of the present invention.

Fig. 24 is a schematic structural view of a terahertz wave transmitting device provided in embodiment 5 of the present invention.

Fig. 25 is a schematic structural diagram of a terahertz wave communication device according to embodiment 6 of the present invention.

Fig. 26 is a block diagram of a decrypting apparatus of a terahertz wave communication apparatus according to embodiment 6 of the present invention.

Fig. 27 is a schematic structural diagram of a terahertz wave communication device according to embodiment 7 of the present invention.

Fig. 28 is a schematic structural diagram of a terahertz wave communication device according to embodiment 8 of the present invention.

Fig. 29 is a schematic structural diagram of a terahertz wave communication device according to embodiment 9 of the present invention.

Fig. 30 is a schematic structural diagram of a terahertz wave wavelength detection apparatus provided in embodiment 10 of the present invention.

Fig. 31 is a block diagram of a computer of a terahertz wave wavelength detecting apparatus according to embodiment 10 of the present invention.

Fig. 32 is a schematic structural diagram of a terahertz wave wavelength detecting device provided in embodiment 11 of the present invention.

Fig. 33 is a schematic structural diagram of a terahertz wave wavelength detecting device provided in embodiment 12 of the present invention.

Fig. 34 is a schematic structural diagram of a terahertz wave wavelength detecting device provided in embodiment 13 of the present invention.

Description of the main elements

Detailed Description

The invention will be described in further detail with reference to the following drawings and specific embodiments.

Example 1

Referring to fig. 1, an embodiment 1 of the present invention provides a terahertz wave transmitting device 10, which includes a terahertz wave source 11 and a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11. The terahertz wave source 11 is used for exciting terahertz waves. The terahertz wave excited by the terahertz wave source 11 is modulated by the modulation device 12 to form terahertz modulation waves and is emitted.

The structure of the terahertz wave source 11 is not limited, and may be an incoherent thermal radiation light source, a wide-band pulse (T-ray) light source, or a narrow-band continuous wave light source.

Referring to fig. 2, the modulation device 12 includes a support frame 120 and a carbon nanotube structure 121. The shape and size of the support frame 120 may be selected as desired. The material of the support frame 120 is not limited, and may be metal, polymer, glass, ceramic, or carbon material, etc. The support frame 120 defines an opening. The edge of the carbon nanotube structure 121 is fixed on the supporting frame 120, and the middle portion is suspended by the supporting frame 120. The carbon nanotube structure 121 may be fixed to the support frame 120 by an adhesive. The carbon nanotube structure 121 may be directly disposed on the emission surface 111 of the terahertz wave source 11, or may be disposed at an interval from the emission surface 111 of the terahertz wave source 11. When the carbon nanotube structure 121 may be directly disposed on the emission surface 111 of the terahertz wave source 11, the support frame 120 may be omitted.

The carbon nanotube structure 121 includes a plurality of carbon nanotubes extending along the same direction and forming a plurality of uniformly distributed micropores. The carbon nanotubes are tightly connected by van der waals force so that the carbon nanotube structure 121 forms a self-supporting structure. By self-supporting structure is meant that the structure can maintain a particular membrane-like structure without the need for a support. Therefore, the carbon nanotube structure 121 is self-supporting and can be partially suspended. The carbon nanotubes are parallel to the surface of the carbon nanotube structure 121. The carbon nanotubes include one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes. The diameter of the single-walled carbon nanotube is 0.5 to 10 nanometers, the diameter of the double-walled carbon nanotube is 1.0 to 15 nanometers, and the diameter of the multi-walled carbon nanotube is 1.5 to 50 nanometers. The carbon nanotubes have a length greater than 50 microns. Preferably, the carbon nanotubes have a length of 200 to 900 micrometers. The size of the micropores 116 is 1 nm to 0.5 μm. Specifically, the carbon nanotube structure 121 may include at least one drawn carbon nanotube film or a plurality of carbon nanotube wires arranged in parallel and at intervals. The carbon nanotube wire may be a non-twisted carbon nanotube wire or a twisted carbon nanotube wire.

Referring to fig. 3, the drawn carbon nanotube film includes a plurality of continuous and directionally extending carbon nanotube bundles. The plurality of carbon nanotube bundles are connected end-to-end by van der waals forces. Each carbon nanotube bundle includes a plurality of mutually parallel carbon nanotubes that are tightly bound by van der waals forces. The diameter of the carbon nanotube bundle is 10 nm to 200 nm, preferably, 10 nm to 100 nm. The carbon nano tubes in the carbon nano tube drawing film are arranged along the same direction in a preferred orientation mode. The carbon nanotube drawn film comprises a plurality of micropores. The micro-hole is a through hole penetrating through the thickness direction of the carbon nano tube drawn film. The micropores may be pores and/or interstices. When the carbon nanotube structure 121 includes only a single-layer drawn carbon nanotube film, a gap is formed between adjacent carbon nanotube segments in the drawn carbon nanotube film, wherein the size of the gap is 1 nm to 0.5 μm. The thickness of the carbon nano tube drawing film is 0.01-100 microns. It can be understood that in the carbon nanotube structure 121 composed of the drawn multi-layered carbon nanotube film, the arrangement directions of the carbon nanotubes in two adjacent drawn carbon nanotube films are the same. The carbon nanotube drawn film can be directly obtained by drawing a carbon nanotube array. Please refer to chinese patent No. CN101239712B, which is published on 5/26/2010 by dawn et al, CN101239712B, a structure of the drawn carbon nanotube film and a method for preparing the same, in 2007 and 2/9, applicant: qinghua university, hong Fujin precision industry (Shenzhen) limited. For the sake of brevity, this is incorporated herein by reference, and all technical disclosure of the above-mentioned applications should be considered as part of the technical disclosure of the present application.

Referring to fig. 4, the untwisted carbon nanotube wire comprises a plurality of carbon nanotubes arranged along the length of the untwisted carbon nanotube wire. Specifically, the untwisted carbon nanotube wire comprises a plurality of carbon nanotube segments, the plurality of carbon nanotube segments being connected end to end by van der waals forces, each of the carbon nanotube segments comprising a plurality of carbon nanotubes parallel to each other and tightly bound by van der waals forces. The carbon nanotube segments have any length, thickness, uniformity, and shape. The length of the untwisted carbon nano tube line is not limited, and the diameter is 0.5 nanometer to 100 micrometers. The untwisted carbon nanotube wire is obtained by processing a carbon nanotube film by an organic solvent. Specifically, an organic solvent is infiltrated into the whole surface of the carbon nanotube drawn film, and under the action of surface tension generated when the volatile organic solvent is volatilized, a plurality of carbon nanotubes which are parallel to each other in the carbon nanotube drawn film are tightly combined through van der waals force, so that the carbon nanotube drawn film is shrunk into a non-twisted carbon nanotube wire. The organic solvent is a volatile organic solvent, such as ethanol, methanol, acetone, dichloroethane or chloroform, in this embodiment ethanol is used. The carbon nanotube film treated with the organic solvent has a reduced specific surface area and a reduced viscosity compared to a carbon nanotube film not treated with the organic solvent.

The twisted carbon nanotube wire is obtained by twisting the two ends of the carbon nanotube film in opposite directions by using a mechanical force. Referring to fig. 5, the twisted carbon nanotube wire includes a plurality of carbon nanotubes spirally arranged around the axis of the twisted carbon nanotube wire. Specifically, the twisted carbon nanotube wire includes a plurality of carbon nanotube segments connected end to end by van der waals force, each of the carbon nanotube segments including a plurality of carbon nanotubes parallel to each other and tightly bound by van der waals force. The carbon nanotube segments have any length, thickness, uniformity, and shape. The length of the twisted carbon nano tube line is not limited, and the diameter is 0.5 to 100 micrometers. Further, the twisted carbon nanotube wire may be treated with a volatile organic solvent. Under the action of surface tension generated when the volatile organic solvent is volatilized, adjacent carbon nanotubes in the processed twisted carbon nanotube wire are tightly combined through van der waals force, so that the specific surface area of the twisted carbon nanotube wire is reduced, and the density and the strength are increased.

Please refer to chinese patent No. CN100411979C, which is published on 8/20/2002 by dawn et al, "a carbon nanotube rope and a method for manufacturing the same", for the linear structure of the carbon nanotube and the method for manufacturing the same, in 2002: qinghua university, hong fu jin precision industry (shenzhen) limited, and chinese published patent application No. CN100500556C published on 6.17.2009, which was applied on 12.16.2005 and 6.2009, the applicant: qinghua university, hong Fujin precision industry (Shenzhen) limited. For the sake of brevity, this is incorporated herein by reference, and all technical disclosure of the above-mentioned applications should be considered as part of the technical disclosure of the present application.

Embodiment 1 of the present invention further provides a method of generating a terahertz modulation wave, including the steps of:

step S11, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave; and

step S12, a carbon nanotube structure 121 is disposed on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 is emitted after passing through the carbon nanotube structure 121, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending along the same direction.

In step S12, the terahertz wave generated by the terahertz wave source 11 is modulated by the carbon nanotube structure 121 to form a terahertz polarized wave.

The inventor of the present application has found that the transmittance of the terahertz wave can be adjusted through the carbon nanotube structure 121, that is, the transmittance of the terahertz wave is in a shape of alternating peaks and troughs with the wave number or wavelength. In this embodiment, the carbon nanotube drawn films of 1 layer, 2 layers, 3 layers, 4 layers, and 5 layers are respectively used for measurement, the extending directions of the carbon nanotubes of the drawn films of the multi-layer carbon nanotube are the same, and the extending directions of the carbon nanotubes are respectively the horizontal direction and the vertical direction.

Referring to fig. 6, in a far infrared band with wave number of 680-30 and wavelength range of 15-300 microns, the transmittance of terahertz waves is in an obvious alternating shape of peaks and troughs along with the wave number no matter the extending direction of the carbon nanotube is in the horizontal direction or the vertical direction. Moreover, when the extending directions of the carbon nanotubes are the horizontal direction and the vertical direction, respectively, the peaks and the troughs are opposite. For example, in the wave number range of 475 to 300, the transmittance is in a valley shape when the extending direction of the carbon nanotube is horizontal, and in a peak shape when the extending direction of the carbon nanotube is vertical. In addition, as the number of the carbon nanotube film drawing layers increases, the transmittance of the terahertz wave gradually decreases, but the terahertz wave is in a wave crest and wave trough alternating shape along with the wave number. Moreover, as the number of the carbon nanotube film drawing layers increases, when the extending directions of the carbon nanotubes are respectively the horizontal direction and the vertical direction, the contrast of the peaks and the troughs is gradually increased. For example, in the wave number range of 475-300, the contrast between the peaks and the troughs is obviously increased gradually with the increase of the number of the carbon nanotube film drawing layers.

Referring to fig. 7, in the mid-infrared band with a wave number of 7500-400 and a wavelength range of 1.3-25 micrometers, the transmittance of the terahertz wave is also in a certain peak-valley alternating shape along with the wave number no matter the extending direction of the carbon nanotube is in the horizontal direction or the vertical direction, but compared with the far-infrared band, the peak-valley alternating phenomenon is less obvious. In addition, as the number of layers of the carbon nanotube drawn film increases, the penetration rate of the terahertz wave gradually decreases. But the alternating phenomena of peaks and troughs are gradually intensified. For example, when a 5-layer carbon nanotube film is drawn, a distinct alternating peak-to-valley phenomenon can be seen.

Further, in this example, the measurement was performed using crossed carbon nanotube drawn films of 2 layers and 4 layers, respectively. When the 2-layer carbon nanotube drawing film is adopted, the extending direction of the carbon nanotubes of the 2-layer carbon nanotube drawing film is vertical. When the 4-layer carbon nanotube drawing film is adopted, the extending directions of the carbon nanotubes in the 1 st and 3 rd carbon nanotube drawing films are the same, the extending directions of the carbon nanotubes in the 2 nd and 4 th carbon nanotube drawing films are the same, and the extending directions of the carbon nanotubes in the 1 st and 2 nd carbon nanotube drawing films are vertical. Referring to fig. 8, in the far infrared band, when the crossed carbon nanotube drawn films of 2 and 4 layers are rotated by 0 degrees, 90 degrees, 180 degrees, and 270 degrees, the measurement results are substantially the same, and there is no peak-valley alternation phenomenon. It can be seen that the alternating peaks and troughs is caused by the periodic alignment and stretching of the carbon nanotubes in the carbon nanotube structure 121. Because the gap between adjacent carbon nanotubes is equal to the wavelength of the terahertz wave, the terahertz wave interferes when passing through the carbon nanotube structure 121, and thus the phenomenon of alternating peaks and troughs is generated. The alternating peak and valley phenomenon is macroscopically expressed as a polarization characteristic.

Example 2

The terahertz wave transmitting device 10 provided in embodiment 2 of the present invention has substantially the same structure as the terahertz wave transmitting device 10 provided in embodiment 1 of the present invention, and the difference is that the surface of the carbon nanotube directionally extending in the same direction in the carbon nanotube structure 121 is coated with a prefabricated layer. Preferably, the prefabricated layer covers the whole surface of each carbon nanotube.

The material of the prefabricated layer can be at least one of metals such as gold, nickel, titanium, iron, aluminum, titanium, chromium and the like, metal oxides such as aluminum oxide, magnesium oxide, zinc oxide, hafnium oxide and the like, metal nitrides, metal sulfides and the like. It is to be understood that the material of the preliminary layer is not limited to the above-mentioned materials, and may be a nonmetallic oxide such as silicon dioxide, a nonmetallic carbide such as silicon carbide, a nonmetallic nitride such as silicon nitride, or the like, as long as the material can be physically deposited on the surface of the carbon nanotube structure 121 and coats the carbon nanotubes. The physical deposition means that the prefabricated layer does not chemically react with the carbon nanotube structure 121, but is tightly bonded to the carbon nanotube structure 121 by van der waals force and attached to the surface of the carbon nanotube in the carbon nanotube structure 121. The thickness of the prefabricated layer is not limited and can be 3-50 nanometers.

In this embodiment, an aluminum oxide layer and a gold layer are respectively disposed on the surface of the single-layer carbon nanotube drawn film by an electron beam evaporation method as a prefabricated layer for measurement, wherein the thickness of the prefabricated layer is 15 nanometers and 30 nanometers, and the extending direction of the carbon nanotube is a horizontal direction and a vertical direction.

Referring to fig. 9, in the far infrared band, the phenomenon of alternating peaks and valleys is still apparent regardless of whether the extending direction of the carbon nanotubes is the horizontal direction or the vertical direction. However, compared with a pure carbon nanotube drawn film, after the aluminum oxide layer is coated, the alternating phenomenon of wave crests and wave troughs is weakened, and after the gold layer is coated, the alternating phenomenon of wave crests and wave troughs is obviously enhanced. Moreover, the transmittance of the sample coated with the gold layer has a significant tendency to increase at low wavenumbers, which is not true for the pure carbon nanotube structure 121. In addition, the penetration rate of the terahertz waves is integrally reduced along with the increase of the thickness of the gold layer, but the phenomenon of alternating peaks and troughs is still obvious.

Referring to fig. 10, in the mid-infrared band, the transmittance of the single-layer carbon nanotube drawn film coated with the gold layer is significantly reduced compared to that of a pure single-layer carbon nanotube drawn film, but the phenomenon of alternating peaks and troughs is significantly enhanced compared to that of a pure single-layer carbon nanotube drawn film. And the phenomenon of alternating wave crests and wave troughs of the single-layer carbon nano tube film coated with the aluminum oxide layer almost disappears.

As a typical metal material, gold absorbs electromagnetic wave energy mainly from its carrier electrons. This is similar to carbon nanotube film materials. However, since gold has a much larger number of electrons than carbon nanotubes, the introduction of a small amount of gold has a considerable effect on the transmittance of the carbon nanotube film. From this point, we can effectively adjust the transmittance of the carbon nanotube film by metal deposition. The comparison with the coating film of metal oxide shows that the transmittance behavior of the carbon nano tube is really related to electrons, which is called electronic regulation. And the adjustment and control range of the transmittance through electrons is wider, and the whole range from middle infrared to far infrared is covered. The regulation and control is not sensitive to the thickness of a coating film and is more sensitive to materials. In addition, the alternating phenomenon of wave crests and wave troughs of the carbon nanotube film of the evaporated metal layer is obviously enhanced, which shows that the metal layer can also generate the alternating phenomenon of wave crests and wave troughs. After the metal layer is evaporated on the surface of the carbon nano tube film, the terahertz wave transmission is modulated and superposed respectively by the carbon nano tube film and the metal layer which are equivalent to the same structure.

Example 3

Referring to fig. 11 to 12, an embodiment 3 of the present invention provides a terahertz wave transmitting device 10A, which includes a terahertz wave source 11, a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, and a rotation device 13.

A terahertz wave transmitting device 10A provided in embodiment 3 of the present invention has substantially the same structure as the terahertz wave transmitting device 10 provided in embodiment 1 of the present invention, except that it further includes a rotating device 13. The rotating device 13 is configured to rotate the terahertz wave source 11 or/and the modulating device 12, so as to adjust an included angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave. The rotation device 13 may be attached to the terahertz wave source 11, or may be attached to the modulation device 12. Alternatively, one rotating device 13 may be mounted on each of the terahertz wave source 11 and the modulating device 12.

In this embodiment, the rotating device 13 is connected to the supporting frame 120, and is used for rotating the supporting frame 120 so as to rotate the carbon nanotube structure 121 in the plane thereof. The rotating device 13 at least comprises a motor and a control module. The precision of the rotation angle of the carbon nanotube structure 121 is less than or equal to 5 degrees, and preferably, the precision of the rotation angle is 1 degree.

It can be understood that, since the actual polarization direction of the terahertz wave cannot be determined in advance, the present embodiment defines a direction reference perpendicular to the ground, and the extending direction of the carbon nanotube is perpendicular to the ground at an angle of 0 degree. When only the carbon nanotube structure 121 rotates, the angle of rotation of the carbon nanotube structure 121 is the angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave. When the carbon nanotube structure 121 and the terahertz wave source 11 rotate simultaneously, the included angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave can be calculated according to the respective rotation angles of the carbon nanotube structure 121 and the terahertz wave source 11. For example, when the carbon nanotube structure 121 and the terahertz wave source 11 rotate in the same direction, the included angle is the difference between the respective rotation angles of the carbon nanotube structure 121 and the terahertz wave source 11. When the rotation directions of the carbon nanotube structure 121 and the terahertz wave source 11 are opposite, the included angle is the sum of the respective rotation angles of the carbon nanotube structure 121 and the terahertz wave source 11.

Embodiment 3 of the present invention further provides a method of generating a terahertz modulation wave, including the steps of:

step S31, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S32, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 is emitted after penetrating through the carbon nanotube structure 121, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending along the same direction; and

step S33, the terahertz wave source 11 or/and the modulation device 12 are rotated, so as to adjust an included angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave.

In this embodiment, the single-layer carbon nanotube film is drawn for measurement, and the measurement is performed every 15 degrees up to 180 degrees from the 0 degree angle of the extending direction of the carbon nanotube perpendicular to the ground. Referring to fig. 13, the alternating phenomenon of the peaks and the troughs is changed periodically. That is, as the carbon nanotube film is drawn and rotated, the peaks and the valleys are gradually transformed into each other. Referring to fig. 14-15, after the carbon nanotube drawn film is rotated by 90 degrees, the peaks are changed into troughs, the troughs are changed into peaks, and the peaks and the troughs are symmetrical under two angles with a 90-degree difference. Referring to fig. 16, after the carbon nanotube drawn film is rotated by 180 degrees, the shape of the peaks and valleys is the same as the shape of the peaks and valleys at an angle of 0 degrees.

Example 4

Referring to fig. 17, embodiment 3 of the present invention provides a terahertz wave transmitting device 10B, which includes a terahertz wave source 11, a modulating device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a vacuum container 14, and a heating device 15.

A terahertz-wave transmitting apparatus 10B provided in embodiment 4 of the present invention has substantially the same structure as the terahertz-wave transmitting apparatus 10 provided in embodiment 1 of the present invention, except that it further includes a vacuum vessel 14 and a heating device 15. The heating device 15 is used for heating the carbon nanotube structure 121. The modulation device 12 is disposed in the vacuum container 14, and is used for protecting the carbon nanotube structure 121 of the modulation device 12 to prevent the carbon nanotube structure 121 from being oxidized after being heated. In particular, after the surface of the carbon nanotube structure 121 is coated with a metal layer, the metal layer is easily formed into a metal oxide when heated. It can be understood that, since the carbon nanotube structure 121 is disposed in the vacuum container 14, the heating device 15 may be a special electric heating device disposed in the vacuum container 14, or an optical heating device disposed outside the vacuum container 14, such as laser heating. Preferably, the heating is achieved by applying a voltage to the carbon nanotube structure 121 without introducing other heating means than the carbon nanotube structure 121. Since the heat exchange between the other heating means and the carbon nanotube structure 121 is mainly performed by the heat radiation, which introduces other electromagnetic waves, thereby interfering with the adjustment of the terahertz waves.

The vacuum vessel 14 is made of a material through which terahertz waves can penetrate, such as glass or transparent resin. The vacuum degree of the vacuum container 14 is not required to be high as long as the pressure is lower than 100 Pa. It is to be understood that. The vacuum vessel 14 may be filled with an inert gas.

In this embodiment, the heating device 15 includes a first electrode 151, a second electrode 152, and a power source 153. The first electrode 151 and the second electrode 152 are disposed at an interval and are electrically connected to the power supply 153, respectively. The first electrode 151 or the second electrode 152 is a metal layer or a metal sheet. The first electrode 151 and the second electrode 152 are fixed on the support frame 120 and electrically connected to the carbon nanotube structure 121. The carbon nanotube structure 121 is sandwiched between the support frame 120 and the first electrode 151 or the second electrode 152. The power supply 153 may be an ac power supply or a dc power supply. When a voltage is applied to the carbon nanotube structure 121 through the first and

second electrodes

151 and 152, the carbon nanotube structure 121 generates heat by itself.

Referring to fig. 18 to 19, in particular, the length of the carbon nanotube structure 121 is greater than the dimension of the support frame 120 in the length direction. The carbon nanotube structure 121 is disposed on one surface of the supporting frame 120, and both ends of the carbon nanotube structure are respectively bent and disposed on the back surface of the supporting frame 120. The first electrode 151 or the second electrode 152 is a metal ring, and is sleeved on the supporting frame 120, so that the carbon nanotube structures 121 on the front and back sides of the supporting frame 120 are clamped between the supporting frame 120 and the first electrode 151 or the second electrode 152.

It is understood that, in the present embodiment, the carbon nanotube structure 121 is used as a heating element at the same time. In another embodiment, the heating means 15 may comprise a dedicated heating element. For example, referring to fig. 20, the heating device 15 includes a heating film 154 that can be penetrated by terahertz waves, and the heating film 154 is disposed on the inner wall of the vacuum container 14 and electrically connected to the first electrode 151 and the second electrode 152. The heating film 154 is spaced apart from the carbon nanotube structure 121. The material of the heating film 154 may be ITO.

Embodiment 4 of the present invention further provides a method of generating a terahertz modulation wave, including the steps of:

step S41, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S42, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 is emitted after penetrating through the carbon nanotube structure 121, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending along the same direction; and

step S43, heating the carbon nanotube structure 121.

In step S43, the process of heating the carbon nanotube structure 121 may further include changing the temperature of the carbon nanotube structure 121. In this embodiment, the carbon nanotube structure 121 is heated by applying a voltage to both ends of the carbon nanotube structure 121 along the extending direction of the carbon nanotube. The applied voltage range is 0V to 200V. Further, the voltage applied to both ends of the carbon nanotube structure 121 along the extending direction of the carbon nanotube may be a constant voltage or a variable voltage.

In the 1 st test of this embodiment, a single-layer carbon nanotube drawn film is used for measurement, the extending directions of the carbon nanotubes are horizontal and vertical, and the applied voltages are 0V, 30V, 60V, and 90V, respectively. Referring to fig. 21, near the mid-infrared band, the transmittance of the terahertz waves is gradually decreased as the voltage is increased, and near the far-infrared band, the transmittance is drastically decreased. The alternating peaks and valleys phenomenon still remains, but is not apparent.

In the 2 nd test of this embodiment, the single-layer carbon nanotube film is used for measurement, the extending directions of the carbon nanotubes are horizontal and vertical, and the applied voltages are 0V, 20V, 40V, 60V, 80V and 100V, respectively. Referring to fig. 22, as the voltage increases, the transmittance of the far infrared band sharply decreases, and the phenomenon of alternating peaks and valleys can be clearly seen. In addition, the alternating phenomena of peaks and troughs tends to be amplified with the increase of voltage, and some characteristics which are weak or invisible under no voltage tend to be obvious under high voltage. For example, the peaks and valleys around

wave numbers

150, 250, and 600 all become more pronounced as the voltage increases.

In the 3 rd test of this embodiment, the double-walled carbon nanotube film is used for measurement, and other parameters are the same as those in the 2 nd test. Referring to fig. 23, the measurement results using the double-walled carbon nanotube drawn film are substantially the same as the measurement results using the single-walled carbon nanotube drawn film.

It can be appreciated that one important difference between carbon nanotubes and traditional metallic and semiconducting materials is the phonon behavior of carbon nanotubes. As a quasi-particle, phonons play a very important role in the thermal conduction of carbon nanotubes. Since the thermal capacity of electrons and phonons are far from an order of magnitude, the properties of high thermal conductivity and low thermal capacity of carbon nanotubes are essentially derived from phonon contribution. Because the thermal capacity of electrons is very low, and the heat conduction of the carbon nano tube does not depend on electrons but phonons, the transmittance of the carbon nano tube is reduced mainly due to phonon regulation and control, and the direct relation between the transmittance and the electrons is not realized.

In connection with example 2, it can be seen that the effect of the metallized film on the transmittance of the carbon nanotubes covers the mid-infrared and far-infrared bands, while the heating mainly affects the far-infrared band. This indicates that the effect of the heating means on the carbon nanotubes is indeed mechanistically different from that of the metallized film. The energy of the chemical bond of the carbon nanotube is high regardless of the semiconductor type or the metal type. The far infrared band mainly has phonons represented by the vibration of the lattice itself, and the like, and has relatively low energy, mainly in the far infrared range. This can be verified from the study controls of the phonon spectra.

Example 5

Referring to fig. 24, an embodiment 5 of the present invention provides a terahertz wave transmitting device 10C, which includes a terahertz wave source 11, a modulating device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a rotating device 13, a vacuum container 14, and a heating device 15.

The terahertz wave transmitting device 10C provided in embodiment 5 of the present invention has substantially the same structure as the terahertz wave transmitting device 10 provided in embodiment 1 of the present invention, and is different in that it further includes a rotating device 13, a vacuum container 14, and a heating device 15. It can be understood that the terahertz wave transmitting apparatus 10C provided in embodiment 5 of the present invention is a combination of the technical solutions of embodiments 3 and 4. Specifically, the rotating device 13 is connected to the terahertz wave source 11, thereby rotating the terahertz wave source 11.

Example 6

Referring to fig. 25, an embodiment 6 of the present invention provides a terahertz wave communication device 10D, which includes a terahertz wave source 11, a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a rotation device 13, a terahertz wave receiving device 16, a decryption device 17, and an encryption device 18. The terahertz wave source 11 emits terahertz waves, the modulation device 12 modulates the terahertz waves, and the encryption device 18 encrypts the terahertz waves through the rotating device 13. The terahertz wave receiving device 16 is configured to receive terahertz waves and send data of the terahertz waves to the decryption device 17. The decryption device 17 decrypts the received data of the terahertz wave.

Referring to fig. 13, when the rotating device 13 rotates the carbon nanotube structure 121 according to a certain rule, the transmittance of the terahertz wave changes according to a certain rule. Therefore, the rotation rule of the rotating device 13 corresponds to the penetration rate change rule of the terahertz wave. When the rotation rule of the rotating device 13 is adopted to represent different signals, the signal transmitted by the terahertz wave can be obtained by calculating the change rule of the penetration rate of the received terahertz wave. The rotation law of the rotating device 13 can be designed according to requirements, for example, the intervals of the rotation angles are from small to large, the intervals of the rotation angles are from large to small, or the rotation angles are not changed at equal intervals. In short, it is only necessary to have a certain rule. The more complex the rule, the better the security. The encryption device 18 is connected with the rotating device 13 and is a control computer of the rotating device 13.

Referring to embodiment 3, the rotating device 13 is used to adjust an angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave, and therefore, the rotating device 13 can also be disposed on the terahertz wave source 11. And the change rule of the penetration rate of the terahertz waves corresponds to the change rule of the included angle.

The terahertz wave receiving device 16 may be a terahertz wave intensity detecting device to obtain intensity data of the received terahertz wave and transmit the intensity data to the decrypting device 17.

Referring to fig. 26, the decryption apparatus 17 is a computer, and includes a control module 171, a calculating module 172, a comparing module 173, a communication module 174, and a storage module 175. The control module 171 controls the operation of the entire decryption apparatus 17. The communication module 174 is configured to communicate with the terahertz wave receiving device 16 to obtain the intensity data of the terahertz wave received by the terahertz wave receiving device 16. The storage module 175 stores therein raw intensity data of the terahertz waves emitted from the terahertz wave source 11, and a codebook. The code book comprises a corresponding relation between the penetration rate change rule of the terahertz waves and signals transmitted by the terahertz waves. The calculation module 172 may calculate the transmittance of the terahertz wave according to the received terahertz wave intensity data and the stored raw terahertz wave intensity data. The comparison module 173 determines the transmitted signal according to the calculated penetration rate change rule of the terahertz wave and the code book.

Embodiment 6 of the present invention further provides a method for performing communication using a terahertz modulation wave, including the steps of:

step S61, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S62, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 penetrates through the carbon nanotube structure 121 to form a terahertz modulated wave, and the terahertz modulated wave is emitted, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending in the same direction;

step S63, encrypting the terahertz modulation wave by regularly changing the included angle between the extending direction of the carbon nano tube and the polarization direction of the terahertz wave;

step S64, receiving the encrypted terahertz modulation wave by using a terahertz wave receiving device 16, and calculating the transmittance of the terahertz wave; and

and step S65, decrypting the encrypted terahertz modulation wave according to the penetration rate change rule of the terahertz wave.

Because the alternating phenomenon of the wave crests and the wave troughs of the terahertz waves in the far infrared band is more obvious than that in the intermediate infrared band, the terahertz waves with the wavelength range of 15-300 microns are preferably adopted for communication in the embodiment. Because the detection and modulation of the terahertz wave are difficult, the communication method adopting the terahertz wave is safer.

Example 7

Referring to fig. 27, an embodiment 7 of the present invention provides a terahertz wave communication device 10E, which includes a terahertz wave source 11, a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a vacuum container 14, a heating device 15, a terahertz wave receiving device 16, a decryption device 17, and an encryption device 18. The terahertz wave source 11 emits terahertz waves, the modulation device 12 modulates the terahertz waves, and the encryption device 18 encrypts the terahertz waves through the heating device 15. The terahertz wave receiving device 16 is configured to receive terahertz waves and send data of the terahertz waves to the decryption device 17. The decryption device 17 decrypts the received data of the terahertz wave.

The terahertz wave communication device 10E provided in embodiment 7 of the present invention has substantially the same structure as the terahertz wave communication device 10D provided in embodiment 6 of the present invention, except that in embodiment 7 of the present invention, the heating device 15 is used to encrypt the terahertz wave.

Referring to fig. 21 to 23, as the temperature increases, the transmittance of the terahertz wave gradually decreases, and the phenomenon of alternating peaks and valleys can be clearly seen. In addition, the phenomenon of alternating peaks and troughs tends to be amplified with increasing temperature, and some features which are weak or invisible under no voltage tend to be obvious under high voltage. That is, the transmittance of the terahertz wave has a corresponding relationship with the temperature of the carbon nanotube structure 121. As long as the carbon nanotube structure 121 is regularly heated, the transmittance of the terahertz wave also changes according to a certain rule. Therefore, the terahertz wave can be encrypted by regularly heating the carbon nanotube structure 121.

Since the temperature of the carbon nanotube structure 121 is related to the operating parameters of the heating device 15, such as power or voltage, the terahertz wave can be encrypted as long as the operating parameters of the heating device 15 are regularly adjusted. In this embodiment, the carbon nanotube structure 121 is heated by using the joule heat principle, and the heating temperature is related to the applied voltage, so that the terahertz wave can be encrypted by regularly adjusting the applied voltage.

In addition, a temperature sensor (not shown) may be disposed in the vacuum container 14, and the temperature of the carbon nanotube structure 121 is obtained by the temperature sensor, so that the temperature of the carbon nanotube structure 121 is regularly adjusted by the heating device 15. The heating temperature is lower than 500 ℃. Preferably, the heating temperature is lower than 350 degrees celsius in the atmosphere to prevent the carbon nanotube structure 121 from being oxidized.

Embodiment 7 of the present invention further provides a method for performing communication using a terahertz modulation wave, including the steps of:

step S71, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S72, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 penetrates through the carbon nanotube structure 121 to form a terahertz modulated wave, and the terahertz modulated wave is emitted, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending in the same direction;

step S73 of encrypting the terahertz modulated wave by regularly heating the carbon nanotube structure 121;

step S74, receiving the encrypted terahertz modulation wave by using a terahertz wave receiving device 16, and calculating the transmittance of the terahertz wave; and

and step S75, decrypting the encrypted terahertz modulation wave according to the penetration rate change rule of the terahertz wave.

Example 8

Referring to fig. 28, an embodiment 8 of the present invention provides a terahertz wave communication device 10F, which includes a terahertz wave source 11, a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a rotation device 13, a vacuum container 14, a heating device 15, a terahertz wave receiving device 16, a decryption device 17, and an encryption device 18.

The encryption device 18 is connected to the rotation device 13 and the heating device 15, respectively, and encrypts the terahertz waves by the rotation device 13 and the heating device 15. The terahertz wave communication device 10F of embodiment 8 of the present invention is actually a combination of the technical solutions of embodiments 6 and 7. It is understood that, in this embodiment, the change law of the transmittance of the terahertz wave is a superposition of the change laws of the transmittance of the terahertz wave in embodiments 6 and 7. Because two different change rules are superposed, the safety of communication is further improved.

Embodiment 8 of the present invention further provides a method for performing communication using a terahertz modulation wave, including the steps of:

step S81, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S82, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 penetrates through the carbon nanotube structure 121 to form a terahertz modulated wave, and the terahertz modulated wave is emitted, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending in the same direction;

step S83, encrypting the terahertz modulation wave by regularly heating the carbon nanotube structure 121 and regularly changing an angle between an extending direction of the carbon nanotube and a polarization direction of the terahertz wave;

step S84, receiving the encrypted terahertz modulation wave by using a terahertz wave receiving device 16, and calculating the transmittance of the terahertz wave; and

and step S85, decrypting the encrypted terahertz modulation wave according to the penetration rate change rule of the terahertz wave.

Example 9

Referring to fig. 29, an embodiment 9 of the present invention provides a terahertz wave communication device 10G, which includes a terahertz wave source 11, a modulation device 12 disposed on one side of an exit surface 111 of the terahertz wave source 11, a terahertz wave receiving device 16, a decryption device 17, and an encryption device 18. The terahertz wave source 11 emits terahertz waves, the modulation device 12 modulates the terahertz waves, and the encryption device 18 is connected with the terahertz wave source 11 and used for encrypting the terahertz waves. The terahertz wave receiving device 16 is configured to receive terahertz waves and send data of the terahertz waves to the decryption device 17. The decryption device 17 decrypts the received data of the terahertz wave.

The terahertz wave communication device 10G provided in embodiment 9 of the present invention has substantially the same structure as the terahertz

wave communication devices

10D and 10E provided in embodiments 6 and 7 of the present invention, and the difference is that in embodiment 9 of the present invention, the terahertz wave source 11 is directly controlled by the encryption device 18, so as to encrypt the terahertz wave. Therefore, embodiment 9 of the present invention can omit the heating means 15 and the rotating means 13. It is understood that the embodiment 9 of the present invention may further include the heating device 15 and/or the rotating device 13, so as to further improve the safety of communication by superimposing two or three different changing rules.

Specifically, in this embodiment, the terahertz wave is encrypted by controlling the rule of the wavelength range of the terahertz wave emitted by the terahertz wave source 11 over time. Referring to fig. 6, in a far infrared band with a wavelength range of 15 micrometers to 300 micrometers, the transmittance of the terahertz waves is a phenomenon of alternating peaks and valleys, and waveforms of adjacent peaks or valleys are different. For example, when the single-layer carbon nanotube film is horizontally disposed, the four peaks respectively correspond to the wave number ranges: 600-525, 475-300, 250-200, 150-60, and the three wave troughs respectively correspond to wave number ranges: 525-475, 300-250, 200-150. By using different peaks or troughs to represent different symbols, 7 different symbols can be obtained, for example the numbers 1, 2, 3, 4, 5, 6, 7. As long as these peaks or valleys are regularly combined at time intervals, the encryption of the terahertz wave can be realized. For example, with every 5 seconds as a time period, one of the peaks or troughs is sent in each time period, and within 1 minute, 20 regular peaks or troughs, for example, 20 numbers between 1 and 7, can be obtained. It is understood that the peaks or valleys when the single-layered carbon nanotube film is vertically arranged are also equivalent to the far infrared band having a wavelength ranging from 15 to 300 μm, and 14 peaks or valleys, that is, 14 different symbols, can be obtained.

Embodiment 9 of the present invention further provides a method for performing communication using a terahertz modulation wave, including the steps of:

step S91, providing a terahertz wave source 11, and exciting the terahertz wave source 11 to generate a terahertz wave;

step S92, disposing a carbon nanotube structure 121 on one side of the emitting surface 111 of the terahertz wave source 11, so that the terahertz wave generated by the terahertz wave source 11 penetrates through the carbon nanotube structure 121 to form a terahertz modulated wave, and the terahertz modulated wave is emitted, wherein the carbon nanotube structure 121 includes a plurality of carbon nanotubes extending in the same direction;

step S93, encrypting the terahertz modulation wave by controlling a rule of a wavelength range of the terahertz wave emitted by the terahertz wave source 11 with time;

step S94, receiving the encrypted terahertz modulation wave by using a terahertz wave receiving device 16, and calculating the transmittance of the terahertz wave; and

and step S95, decrypting the encrypted terahertz modulation wave according to the penetration rate change rule of the terahertz wave.

Example 10

Referring to fig. 30, an embodiment 10 of the present invention provides a terahertz wave wavelength detecting device 10H, which includes a terahertz wave receiving device 16, a modulating device 12, a moving device 20 connected to the modulating device 12, and a computer 19 connected to the terahertz wave receiving device 16.

The moving device 20 is used to control the modulation device 12, so that the modulation device 12 can be disposed on the incident surface 161 of the terahertz wave receiving device 16 or be deviated from the incident surface 161. The moving device 20 may be a pulling device or a rotating device. When the modulation device 12 is disposed on the incident surface 161 of the terahertz wave receiving device 16, the carbon nanotube structure 121 may be disposed in contact with the incident surface 161 or disposed at a certain distance from the incident surface 161, as long as it is ensured that the detected terahertz wave can only enter the terahertz wave receiving device 16 from the incident surface 161 after passing through the carbon nanotube structure 121. When the modulation device 12 is deviated from the incident surface 161, the terahertz wave to be detected can directly enter the terahertz wave receiving device 16 from the incident surface 161. At this time, the terahertz wave receiving device 16 detects first intensity data of the detected terahertz wave, and transmits the first intensity data to the computer 19. When the modulation device 12 is disposed on the incident surface 161 of the terahertz wave receiving device 16, the detected terahertz waves can enter the terahertz wave receiving device 16 from the incident surface 161 only after passing through the carbon nanotube structure 121. At this time, the terahertz wave receiving device 16 detects second intensity data of the detected terahertz wave and transmits the second intensity data to the computer 19.

Referring to fig. 31, the computer 19 includes a control module 191, a calculation module 192, a comparison module 193, a communication module 194, and a storage module 195. The control module 191 controls the operation of the entire computer 19. The communication module 194 is configured to communicate with the terahertz wave receiving device 16 to obtain the intensity data of the terahertz wave received by the terahertz wave receiving device 16. The storage module 195 stores therein data of the terahertz wave transmittance versus the wave number as shown in fig. 6 to 7. The calculation module 192 can calculate the transmittance curve of the detected terahertz wave according to the second intensity data and the first intensity data. The comparison module 193 can obtain the wavelength range of the detected terahertz waves by comparing the transmittance curve with the data of fig. 6-7. As can be seen from fig. 6, terahertz waves of different wavelength ranges correspond to different transmittance curves. The corresponding relation is particularly obvious in the far infrared band. Therefore, the computer 19 can obtain the wavelength range of the detected terahertz wave by comparing the transmittance curve of the detected terahertz wave with the data of fig. 6 to 7.

Embodiment 10 of the present invention further provides a terahertz wave wavelength detection method, including the following steps:

a step S101 of making a detected terahertz wave directly incident on the terahertz wave receiving device 16, the terahertz wave receiving device 16 detecting first intensity data of the detected terahertz wave;

a step S102 of allowing the detected terahertz wave to be incident on the terahertz wave receiving device 16 after passing through the carbon nanotube structure 121, the terahertz wave receiving device 16 detecting second intensity data of the detected terahertz wave;

step S103, calculating a penetration rate curve of the detected terahertz waves according to the second intensity data and the first intensity data; and

step S104, comparing a standard data of the transmittance curve to obtain a wavelength range of the detected terahertz wave, wherein the standard data includes a relationship between the transmittance of the terahertz wave to the carbon nanotube structure 121 and the wavelength.

Example 11

Referring to fig. 32, an embodiment 11 of the present invention provides a terahertz wave wavelength detecting device 10I, which includes a terahertz wave receiving device 16, a modulating device 12, a rotating device 13 connected to the modulating device 12, a moving device 20 connected to the modulating device 12, and a computer 19 connected to the terahertz wave receiving device 16.

The terahertz wave wavelength detecting device 10I provided in embodiment 11 of the present invention has substantially the same structure as the terahertz wave wavelength detecting device 10H provided in embodiment 10 of the present invention, and is different therefrom in that it further includes a rotating device 13. The rotating device 13 is used for controlling the modulation device 12, so that the modulation device 12 can rotate in the plane where the carbon nanotube structure 121 is located, thereby changing an included angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave. At this time, the terahertz wave receiving device 16 detects third intensity data of the detected terahertz wave at different included angles. The rotating device 13 is connected with the computer 19 in a wired or wireless mode, so that the computer 19 can acquire the rotating angle of the rotating device 13.

The storage module 195 further stores relationship data of the transmittance and the wave number of the terahertz wave and the included angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave as shown in fig. 13. The calculating module 192 may calculate a corresponding relationship between the transmittance curve of the detected terahertz wave and the rotation angle of the rotating device 13 according to the third intensity data, the first intensity data and the rotation angle of the rotating device 13. The comparison module 193 can obtain the wavelength range of the detected terahertz waves by comparing the corresponding relationship between the transmittance curve and the rotation angle of the rotating device 13 with the data in fig. 13.

Embodiment 11 of the present invention further provides a terahertz wave wavelength detection method, including the following steps:

a step S111 of causing the detected terahertz wave to be directly incident on the terahertz wave receiving device 16, the terahertz wave receiving device 16 detecting first intensity data of the detected terahertz wave;

step S112, making the detected terahertz wave incident on the terahertz wave receiving device 16 after penetrating through the carbon nanotube structure 121, and simultaneously changing an included angle between an extending direction of the carbon nanotube in the carbon nanotube structure 121 and a polarization direction of the terahertz wave, where the terahertz wave receiving device 16 detects third intensity data of the detected terahertz wave at different included angles;

step S113, calculating a relationship diagram between the transmittance curve of the detected terahertz wave and the angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave according to the third intensity data, the first intensity data, and the angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave; and

step S114, comparing the relation between the transmittance curve and the angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave with a standard data to obtain the wavelength range of the detected terahertz wave, wherein the standard data includes the relation between the transmittance and the wavelength of the terahertz wave to the carbon nanotube structure 121 and the angle between the extending direction of the carbon nanotube in the carbon nanotube structure 121 and the polarization direction of the terahertz wave.

Example 12

Referring to fig. 33, an embodiment 12 of the present invention provides a terahertz wave wavelength detecting device 10I, which includes a terahertz wave receiving device 16, a modulating device 12, a vacuum container 14, a heating device 15, a moving device 20 connected to the modulating device 12, and a computer 19 connected to the terahertz wave receiving device 16.

A terahertz wave wavelength detecting device 10I provided in embodiment 12 of the present invention has substantially the same structure as the terahertz wave wavelength detecting device 10H provided in embodiment 10 of the present invention, and is different therefrom in that it further includes the vacuum container 14 and the heating device 15. The heating device 15 is used to heat the carbon nanotube structure 121, so as to change the temperature of the carbon nanotube structure 121. At this time, the terahertz-wave receiving device 16 detects fourth intensity data of the detected terahertz wave at a different temperature. The heating device 15 is connected with the computer 19 in a wired or wireless way, so that the computer 19 can obtain the heating voltage of the heating device 15.

The storage module 195 further stores therein data of the relationship between the transmittance of the terahertz wave and the wave number as shown in fig. 21 to 23, and the heating voltage of the heating device 15 (the temperature of the carbon nanotube structure 121). The calculating module 192 may calculate the corresponding relationship between the transmittance curve of the detected terahertz wave and the heating voltage of the heating device 15 (the temperature of the carbon nanotube structure 121) according to the fourth intensity data, the first intensity data and the heating voltage of the heating device 15 (the temperature of the carbon nanotube structure 121). The comparison module 193 can obtain the wavelength range of the detected terahertz wave by comparing the corresponding relationship between the transmittance curve and the heating voltage of the heating device 15 (the temperature of the carbon nanotube structure 121) with the data in fig. 21-23.

It is understood that when a special heating device 15 is used, a temperature sensor (not shown) is required, the carbon nanotube structure 121 and the temperature sensor are disposed in the vacuum container 14, and the heating device 15 is used for heating the carbon nanotube structure 121, so as to change the temperature of the carbon nanotube structure 121. The storage module 195 stores therein data of relationship between the transmittance and the wave number of the terahertz wave to the carbon nanotube structure 121 and the temperature of the carbon nanotube structure 121 as standard data.

Embodiment 12 of the present invention further provides a terahertz wave wavelength detection method, including the following steps:

a step S121 of causing the detected terahertz wave to be directly incident on the terahertz wave receiving device 16, the terahertz wave receiving device 16 detecting first intensity data of the detected terahertz wave;

step S122, making the detected terahertz wave incident on the terahertz wave receiving device 16 after passing through the carbon nanotube structure 121, and simultaneously heating and changing the temperature of the carbon nanotube structure 121, where the terahertz wave receiving device 16 detects fourth intensity data of the detected terahertz wave at different temperatures;

step S123, calculating a relationship diagram between the transmittance curve of the detected terahertz wave and the temperature of the carbon nanotube structure 121 according to the fourth intensity data, the first intensity data and the temperature of the carbon nanotube structure 121; and

step S124, comparing the relationship between the transmittance curve and the temperature of the carbon nanotube structure 121 with a standard data to obtain the wavelength range of the detected terahertz wave, wherein the standard data includes the relationship between the transmittance and the wavelength of the terahertz wave to the carbon nanotube structure 121 and the temperature of the carbon nanotube structure 121.

Example 13

Referring to fig. 34, an embodiment 13 of the present invention provides a terahertz wave wavelength detecting device 10J, which includes a terahertz wave receiving device 16, a modulating device 12, a rotating device 13, a vacuum container 14, a heating device 15, a moving device 20 connected to the modulating device 12, and a computer 19 connected to the terahertz wave receiving device 16.

A terahertz wave wavelength detecting device 10J provided in embodiment 13 of the present invention has substantially the same structure as the terahertz wave wavelength detecting device 10H provided in embodiment 10 of the present invention, and is different therefrom in that it further includes the rotating device 13, the vacuum vessel 14, and the heating device 15.

It can be understood that the terahertz wave wavelength detection device 10J provided in embodiment 13 of the present invention incorporates all the technical solutions of embodiments 10 to 12 of the present invention. The working method of the terahertz wave wavelength detection device 10J provided in embodiment 13 of the present invention may be any one of the working methods in embodiments 10 to 12 of the present invention.

In addition, other modifications within the spirit of the invention may occur to those skilled in the art, and such modifications within the spirit of the invention are intended to be included within the scope of the invention as claimed.

Claims

1. A terahertz wave wavelength detection method comprises the following steps:

directly making a detected terahertz wave incident on a terahertz wave receiving device, wherein the terahertz wave receiving device detects first intensity data of the detected terahertz wave;

enabling the detected terahertz waves to penetrate through a carbon nanotube structure and then to be incident on the terahertz wave receiving device, wherein the terahertz wave receiving device detects second intensity data of the detected terahertz waves, and the carbon nanotube structure comprises a plurality of carbon nanotubes which directionally extend along the same direction;

calculating a transmittance curve of the detected terahertz waves according to the second intensity data and the first intensity data; and

and comparing the penetration rate curve with standard data to obtain the wavelength range of the detected terahertz waves, wherein the standard data comprises data of the relation between the penetration rate of the terahertz waves to the carbon nanotube structure and the wave number.

2. The terahertz wave wavelength detecting method of claim 1, wherein the carbon nanotube structure comprises a carbon nanotube film, the carbon nanotube film comprises a plurality of carbon nanotube bundles connected end to end by van der waals force, and each carbon nanotube bundle comprises a plurality of carbon nanotubes parallel to each other.

3. The method for detecting a wavelength of a terahertz wave as claimed in claim 1, wherein surfaces of the plurality of carbon nanotubes are coated with a metal conductive layer.

4. The method according to claim 1, wherein the carbon nanotube structure is fixed at its edges to a supporting frame, and the middle portion is suspended by the supporting frame.

5. The method for detecting the wavelength of a terahertz wave according to claim 1, wherein the step of transmitting the detected terahertz wave through the carbon nanotube structure further comprises: changing an included angle between the extending direction of the carbon nano tube in the carbon nano tube structure and the polarization direction of the terahertz wave; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the included angle between the extension direction of the carbon nanotube in the carbon nanotube structure and the polarization direction of the terahertz waves.

6. The method for detecting the wavelength of a terahertz wave according to claim 5, wherein the method for changing the included angle between the extending direction of the carbon nanotube in the carbon nanotube structure and the polarization direction of the terahertz wave is to rotate the carbon nanotube structure.

7. The method for detecting the wavelength of a terahertz wave according to claim 1, wherein the step of transmitting the detected terahertz wave through the carbon nanotube structure further comprises: heating the carbon nanotube structure and measuring the temperature of the carbon nanotube structure; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the temperature of the carbon nanotube structure.

8. The method for detecting the wavelength of a terahertz wave according to claim 1, wherein the step of transmitting the detected terahertz wave through the carbon nanotube structure further comprises: applying a voltage across the carbon nanotube structure; the standard data includes data of the transmittance of the terahertz wave to the carbon nanotube structure as a function of the wave number and the voltage applied to the carbon nanotube structure.

9. The method for detecting the wavelength of a terahertz wave according to claim 1, wherein the step of transmitting the detected terahertz wave through the carbon nanotube structure further comprises: rotating and heating the carbon nanotube structure; the standard data comprises relation data of the penetration rate and the wave number of the terahertz waves to the carbon nanotube structure and the temperature and the rotation angle of the carbon nanotube structure.

10. The method according to any one of claims 7 to 9, wherein the carbon nanotube structure is suspended in a vacuum container.