CN106299978B - System occurs for the Terahertz based on unidirectional carrier transport photodetector - Google Patents

Abstract

The invention relates to a terahertz generation system of a unidirectional carrier transport photodetector. The terahertz generation system of the unidirectional carrier transport photodetector includes a picosecond pulse laser, a transmission module, a beam splitter, an amplitude modulation module, a unidirectional carrier transport photodetector and a terahertz detection device. The picosecond pulse laser emits a picosecond two-level pulse laser with a high repetition rate, which is transmitted through the transmission module and can realize spectral broadening of the picosecond pulse laser to obtain a pulse width of tens to hundreds of femtoseconds. After being modulated by the amplitude modulation module, it is input to the unidirectional carrier transport photodetector. Since the unidirectional carrier transport photodetector can achieve high light intensity and high rate transmission characteristics, it can excite high power and high rate Terahertz pulse signal, so as to realize high-power, high-speed terahertz pulse signal communication.

Description

Terahertz generation system based on unidirectional carrier transport photodetector

technical field

The invention relates to the field of terahertz technology, in particular to a terahertz generation system based on a unidirectional carrier transport photodetector.

Background technique

The terahertz frequency band is considered to be one of the target frequency bands for next-generation communications due to its huge bandwidth resources comparable to the optical frequency band at the device level. Sufficient research, and compared to optical frequency band communication, in addition to continuous wave modulation and signal transmission, pulse transmission is also a mainstream method. Compared with continuous wave modulation transmission, pulse transmission has a wider bandwidth and a higher communication rate. , the pulse holds the advantage of a longer distance.

At present, in the terahertz frequency band, continuous wave modulation is the mainstream method of signal loading, and pulse modulation is difficult to achieve high-speed transmission due to problems such as low repetition rate (repetition rate) and low pulse power.

Contents of the invention

Based on this, it is necessary to provide a terahertz generation system based on a unidirectional carrier transport photodetector with high repetition rate and high pulse power to solve the above problems.

A terahertz generation system based on a unidirectional carrier transport photodetector, comprising:

Picosecond pulse laser, used to emit picosecond pulse laser;

A transmission module, configured to transmit the picosecond pulse laser and realize the expansion of the picosecond pulse laser;

A beam splitter for splitting the stretched picosecond pulse laser light into pump light and probe light;

An amplitude modulation module, configured to receive the pump light and the probe light respectively, and perform switch signal modulation on the pump light, and light intensity modulation on the probe light;

a unidirectional carrier transport photodetector, arranged in the propagation direction of the pump light, for exciting the pump light and radiating a terahertz pulse signal;

A terahertz detection device, configured to receive the detection light and detect the terahertz pulse signal.

In one of the embodiments, the transmission module includes a highly nonlinear optical fiber, and the highly nonlinear optical fiber is used to transmit picosecond pulsed laser light and stretch the picosecond pulsed laser light.

In one embodiment, the transmission module further includes a single-mode fiber connected to the highly nonlinear fiber, and the single-mode fiber performs dispersion compensation on the stretched picosecond pulse laser.

In one of the embodiments, the amplitude modulation module includes a first amplitude modulator and a second amplitude modulator, the first amplitude modulator is arranged in the propagation direction of the pump light, and is used to load a switch modulation signal ;

The second amplitude modulator is arranged in the propagation direction of the detection light, and is used for performing light intensity modulation on the detection light.

In one embodiment, the terahertz detection device includes an optical delay line module and a photoconductive antenna, the optical delay line module is used to adjust the time delay between the pump light and the probe light, and the photoconductive antenna is used to detecting the terahertz pulse signal.

In one of the embodiments, the terahertz detection device includes an optical delay line module and an envelope detector, the optical delay line module is used to adjust the time delay between the pump light and the probe light, and the envelope The detector is used to detect the terahertz pulse signal.

In one of the embodiments, an erbium-doped fiber amplifier is also included, and the erbium-doped fiber amplifier is arranged between the picosecond pulse laser and the transmission module, and is used for amplifying the picosecond pulse laser.

In one of the embodiments, the beam splitter is a fiber coupler, the input end of the fiber coupler is connected to the single-mode fiber, and the first output end of the fiber coupler is used to output the pump light, the second output end of the fiber coupler is used to output the detection light.

In one of the embodiments, the beam splitter is a beam splitter.

In one of the embodiments, the repetition frequency of the picosecond pulse laser is greater than or equal to 10 GHz.

The terahertz generation system of the unidirectional carrier transport photodetector includes a picosecond pulse laser, a transmission module, a beam splitter, an amplitude modulation module, a unidirectional carrier transport photodetector and a terahertz detection device. The picosecond pulse laser emits a picosecond two-level pulse laser with a high repetition rate, which is transmitted through the transmission module and can realize spectral broadening of the picosecond pulse laser to obtain a pulse width of tens to hundreds of femtoseconds. After being modulated by the amplitude modulation module, it is input to the unidirectional carrier transport photodetector. Since the unidirectional carrier transport photodetector can achieve high light intensity and high rate transmission characteristics, it can excite high power and high rate Terahertz pulse signal, so as to realize high-power, high-speed terahertz pulse signal communication.

Description of drawings

Figure 1 is an optical circuit diagram of a terahertz generation system based on a unidirectional carrier transport photodetector.

Marks in the figure: picosecond pulse laser 1, erbium-doped fiber amplifier 2, highly nonlinear fiber 3-1, single-mode fiber 3-2, fiber coupler 4, first amplitude modulator 5-1, second amplitude modulator 5-2. Unidirectional carrier transport photodetector 6, optical delay line module 7-1, photoconductive antenna 7-2.

detailed description

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in Figure 1 is the optical path diagram of the terahertz generation system based on the unidirectional carrier transport photodetector; the terahertz generation system based on the unidirectional carrier transport photodetector includes a picosecond pulse laser 1, a transmission module 3. A beam splitter 4, an amplitude modulation module 5, a unidirectional carrier transport photodetector 6 and a terahertz detection device 7. The picosecond pulse laser 1 emits a picosecond two-level pulse laser with a high repetition rate, which is transmitted by the transmission module 3 and can realize spectral broadening of the picosecond pulse laser to obtain a pulse width of tens to hundreds of femtoseconds. After being modulated by the amplitude modulation module 5, it is input to the unidirectional carrier transport photodetector 6. Since the unidirectional carrier transport photodetector 6 can achieve high light intensity and high speed transmission characteristics, it can excite high power, High-rate terahertz pulse signal, so as to realize high-power, high-speed terahertz pulse signal communication. At the same time, the terahertz detection device 7 can also detect the radiated terahertz pulse signal.

The picosecond pulse laser 1 is used for emitting picosecond pulse laser. Picosecond Pulse Laser 1 is a laser with a picosecond pulse width. It has the characteristics of picosecond-level ultra-short pulse width, adjustable repetition frequency, and high pulse energy. In one embodiment, the repetition frequency of the picosecond pulse laser 1 is greater than or equal to 10 GHz, and the pulse width is about 1.5 picoseconds (ps).

In one embodiment, the terahertz generation system based on the unidirectional carrier transport photodetector 6 further includes an erbium doped fiber amplifier (Erbium Doped Fiber Application Amplifier, EDFA) 2, and the erbium doped fiber amplifier 2 is arranged on the Between the picosecond pulse laser 1 and the transmission module 3 is used for amplifying the picosecond pulse laser. For the input picosecond pulse laser, when the pulse width is constant, obviously the higher the peak power, the better the spectrum spreading effect, and the pulse can be amplified by the erbium-doped fiber amplifier 2 to increase its peak power.

In other embodiments, an Optical Fiber Raman Amplifier (OFRA) can also be used to amplify the pulsed laser to provide the peak power of the picosecond pulsed laser.

The transmission module 3 is configured to transmit the picosecond pulsed laser and realize the stretching of the picosecond pulsed laser. The transmission module 3 includes a high nonlinear fiber (High Nonlinear Fiber, HNLF) 3-1, and the high nonlinear fiber 3-1 is used to transmit the picosecond pulse laser and stretch the picosecond pulse laser. Only a small pump light power and a short high nonlinear fiber 3-1 are required to achieve efficient nonlinear effects, and by increasing the supercontinuum (Supercontinuum, SC) of the high nonlinear fiber 3-1 Generating efficiency, pulse spectral broadening can be achieved.

The transmission module 3 also includes a single-mode fiber (Single Mode Fiber, SMB) 3-2, the single-mode fiber 3-2 is connected to the highly nonlinear fiber 3-2, and the single-mode fiber 3-2 pairs Dispersion compensation is performed on the stretched picosecond pulse laser.

The picosecond pulse laser amplified by the erbium-doped fiber amplifier 2 passes through a high-normal dispersion high-non-linear fiber 3-1 to obtain a linear positive chirped SC pulse with spectral broadening, and then passes through a standard single-mode fiber 3-2 of corresponding length for chirping Chirp compensation compression is used to increase the peak power of the pulse again, and at the same time, dispersion compensation can be performed, so that a picosecond pulse laser with a pulse width of tens to hundreds of femtoseconds and a repetition rate of up to 10 GHz can be obtained to achieve spectral broadening.

In this embodiment, in the terahertz generation system based on the unidirectional carrier transport photodetector 6, the beam splitter 4, the amplitude modulation module 5, the unidirectional carrier transport photodetector 6 and the terahertz detection device A highly nonlinear optical fiber 3-1 can also be set between 7 to transmit the picosecond pulse laser, which can greatly reduce the size of the transmission space, has miniaturization, and is convenient for installation and debugging.

The beam splitter 4 is used to split the stretched picosecond pulse laser into pump light and probe light. In one embodiment, the beam splitter 4 is a fiber coupler (Splitter) 4, the input end of the fiber coupler 4 is connected to the single-mode fiber 3-2, and the first output end of the fiber coupler 4 It is used to output the pump light, and the second output end of the fiber coupler 4 is used to output the probe light.

In other embodiments, the beam splitter 4 may also be a beam splitter. The selection of the specific beam splitter 4 can be set according to actual requirements.

The amplitude modulation module 5 receives the pump light and the probe light respectively, and is used for performing switch signal modulation on the pump light and light intensity modulation on the probe light. The amplitude modulation module 5 includes a first amplitude modulator (Amplitude Modulation, AM) 5-1 and a second amplitude modulator 5-2. The first amplitude modulator 5-1 and the second amplitude modulator 5-2 are time-synchronized with the picosecond pulsed laser.

The first amplitude modulator 5-1 is arranged in the propagation direction of the pump light, and is used for loading an on-off modulation signal, which is also called an on-off keying signal (On Off Keying, OOK). That is to say, the digital modulation in which the amplitude of the pump light changes with the digital baseband signal (the digital baseband signal is binary), and it uses a unipolar non-return-to-zero code sequence to control the on and off of the pump light wave.

The picosecond pulse laser output from the first amplitude modulator 5-1 is input to the unidirectional carrier transport photodetector 6 (Uni Traveling Carrier Photo-detector, UTC-PD, which is set in the unidirectional carrier transport photodetector The rear antenna of the detector 6 can radiate the terahertz pulse signal. Since the unidirectional carrier transport photodetector 6 has a high responsivity, it can realize the high-rate output of high-intensity incident light and large current, that is, the detection light The transmission in the unidirectional carrier transport photodetector 6 can excite a high-power, high-rate terahertz pulse signal.

In order to avoid damage to devices in the terahertz detection module due to excessive power of the picosecond pulsed laser, the second amplitude modulator 5-2 is provided in the propagation direction of the detection light. The second amplitude modulator 5-2 is used for performing light intensity modulation on the detection light. The second amplitude modulator 5-2 can reduce the pulse repetition frequency of the detection end by several orders of magnitude, so as to reduce the power of the detection end.

The detection light modulated by the second amplitude modulator 5-2 enters the terahertz detection device 7, and the radiated terahertz pulse signal is also sent to the terahertz detection device 7, and then the radiated terahertz pulse signal is detected.

In one embodiment, the terahertz detection device 7 includes an optical delay line module 7-1 and a photoconductive antenna (Photoconductive Antenna, PCA) 7-2, and the optical delay line module 7-1 is used to adjust the pumping The time delay between light and detection light, the photoconductive antenna 7-2 is used to detect the terahertz pulse signal.

In another embodiment, the terahertz detection device includes an optical delay line module and an envelope detector, the optical delay line module is used to adjust the time delay between the pump light and the probe light, and the envelope The detector is used to detect the terahertz pulse signal. Wherein, the envelope detector is a linear/non-linear envelope detector with large bandwidth. Certainly, a suitable detector such as a linear/nonlinear large-bandwidth envelope detector or a photoconductive antenna may be selected according to an actual application scenario, but it is not limited thereto.

Through the above-mentioned terahertz generation system based on the unidirectional carrier transport photodetector 6, a picosecond pulse generator with a high repetition rate is used to generate pulses above 10 GHz, and at the same time, a unidirectional carrier transport photodiode (UTC-PD) is used Guarantee the power of terahertz transmission and realize high-rate terahertz pulse communication.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (9)

1. system occurs for a kind of Terahertz based on unidirectional carrier transport photodetector, it is characterised in that including：

Picosecond pulse laser, for launching picosecond pulse laser, the repetition rate of the picosecond pulse laser is more than or equal to 10GHz；

Transport module, for transmitting the picosecond pulse laser and realizing the broadening of the picosecond pulse laser；

Beam splitter, for the picosecond pulse laser of broadening to be divided into pump light and detection light；

Amplitude modulation(PAM) module, switching signal tune is carried out for receiving the pump light and detection light respectively, and to the pump light Make, light intensity modulation is carried out to the detection light；

On unidirectional carrier transport photodetector, the direction of propagation for being arranged on the pump light, for exciting the pump light And terahertz pulse signal is given off, and ensure the power of the terahertz pulse signal transmitting；

Terahertz detection device, for receiving the detection light and being detected to the terahertz pulse signal.

2. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, the transport module includes highly nonlinear optical fiber, the highly nonlinear optical fiber is used to transmit picosecond pulse laser and to institute State picosecond pulse laser and enter line broadening.

3. system, its feature occur for the Terahertz according to claim 2 based on unidirectional carrier transport photodetector It is, the transport module also includes single-mode fiber, the single-mode fiber is connected with the highly nonlinear optical fiber, the single-mode optics The fine picosecond pulse laser to broadening processing carries out dispersion compensation.

4. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, the amplitude modulation(PAM) module includes the first amplitude modulator and the second amplitude modulator, first amplitude modulator is set Put on the direction of propagation of the pump light, for loaded switches modulated signal；

Second amplitude modulator is arranged on the direction of propagation of the detection light, strong for carrying out light intensity to the detection light Degree modulation.

5. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, the terahertz detection device includes optical delay wire module and photoconductive antenna, the optical delay wire module is used for The time delay of the pump light and detection light is adjusted, the photoconductive antenna is used to detect the terahertz pulse signal.

6. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, the terahertz detection device includes optical delay wire module and envelope detector, the slow wire module of optics that prolongs is used for The time delay of the pump light and detection light is adjusted, the envelope detector is used to detect the terahertz pulse signal.

7. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, in addition to erbium-doped fiber amplifier, the erbium-doped fiber amplifier is arranged on the picosecond pulse laser and transmission mould Between block, for being amplified processing to picosecond pulse laser.

8. system, its feature occur for the Terahertz according to claim 3 based on unidirectional carrier transport photodetector It is, the beam splitter is fiber coupler, the input of the fiber coupler is connected with the single-mode fiber, the optical fiber First output end of coupler is used to export the pump light, and the second output end of the fiber coupler is used to export the spy Light-metering.

9. system, its feature occur for the Terahertz according to claim 1 based on unidirectional carrier transport photodetector It is, the beam splitter is beam splitter.