JP7609268B2 - Optical monitor device and optical intensity measuring method - Google Patents

Description

The present disclosure relates to an optical monitoring device, and more particularly to an optical monitoring device for detecting the intensity of light in an optical transmission device or the like and feeding back the detection result to other components.

In recent years, with the increase in Internet traffic, there is a strong demand for increasing communication capacity in communication systems. To achieve this, communication systems using optical fibers are used in access networks between communication offices and user homes and in core networks connecting communication offices. In optical fiber communication, detection of the light intensity propagating through optical fibers is often used to control communication and check the soundness of facilities. For example, in access networks, test light is propagated through optical fibers, and the loss and soundness of optical fibers, the target and connection of core wires, etc. are confirmed by detecting the light intensity. In addition, WDM (Wavelength Division Multiplexing) transmission used in core networks requires monitoring of light intensity for feedback control.

For example, technology such as that described in Patent Document 1 is used for optical power monitoring in access networks. Patent Document 1 describes a technology for splitting light at a constant splitting ratio using two parallel waveguides, which makes it possible to measure the optical signal power and propagation loss in the access network.

For example, the technology of Patent Document 2 is used for monitoring the optical intensity in WMD transmission. Patent Document 2 describes a technology for simultaneously monitoring the optical signal intensity of a plurality of optical fibers by combining optical fibers arranged one-dimensionally with a dielectric multilayer film.

However, the conventional optical monitor device still has the following problems.

As optical communications become more widespread and the number of optical fiber cores in optical facilities/optical cables increases, firstly, in the case of optical monitoring devices that use an optical coupler for each optical fiber core, the cost and size increase in proportion to the number of cores.Even in the case of optical monitoring devices in which optical fibers and optical intensity sensors are arranged in a one-dimensional array, there is a limit to the array arrangement of optical fibers, and if the number of optical fiber cores increases beyond that, the cost and size increase in proportion to the number of cores.

In addition, the optical fibers and the light intensity sensors must correspond one-to-one, and the sensors and optical fibers must be arranged at the same pitch. Furthermore, the optical fibers must be positioned accurately so that the light enters the sensors.

Patent No. 3450104 (Furukawa Electric) JP 2004-219523 (Fujitsu, withdrawn)

The present disclosure has been made in consideration of the above points, and aims to provide an optical monitor device having a small size and having several tens of cores that can be manufactured at low cost.

The optical monitor device of the present disclosure comprises:
An optical monitor device for detecting the intensity of light propagating through a plurality of optical fibers, comprising:
an optical component that splits a part of the incident light from the plurality of optical fibers in a first direction and the rest in a second direction at a constant split ratio and outputs the split light;
a light receiving unit that receives light emitted from the optical component in a second direction;
Equipped with
The light receiving unit is
a light receiving surface having a size capable of receiving all of the light emitted from the optical component in the second direction;
On the light receiving surface, light receiving elements, the number of which is greater than the number of the optical fibers, are arranged two-dimensionally.

The light intensity measurement method of the present disclosure includes:
A light intensity measurement method for collectively measuring the intensity of light propagating through a plurality of optical fibers using an optical monitor device according to the present disclosure, comprising the steps of:
measuring a received light intensity at each light receiving element when the light is emitted from each of the plurality of optical fibers, thereby obtaining a correspondence relationship between the plurality of optical fibers and each light receiving element in advance;
Detecting the light intensity of each light receiving element received by the light receiving unit while the plurality of optical fibers are propagating light to be measured;
Based on the correspondence relationship, for each of the plurality of optical fibers,
(i) the light intensity received by the light receiving unit;
(ii) the light intensity of the incident light from the plurality of incident side optical fibers;
(iii) the light intensities of the output lights outputted to the plurality of output side optical fibers;
At least one of the above is measured.

According to the present disclosure, since light is received using a light receiving section having a light receiving surface with a number of light receiving elements arranged two-dimensionally, which number is greater than the number of optical fibers, it is possible to realize a small-sized and low-cost optical monitor device for optical fibers with a large number of cores, such as several tens of cores. Also, according to the present disclosure, highly accurate positioning of the light receiving elements is not required.

1 illustrates an example embodiment of an optical monitor device of the present disclosure. 1 shows an example of the arrangement of the incident side optical fiber. 3 shows an example of the arrangement of light receiving elements in a light receiving section. 1 shows an example of light propagating through a spatial optical system. 1 illustrates an example embodiment of an optical monitor device of the present disclosure.

Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings are assumed to indicate the same components.

(First embodiment)
The optical monitoring device of this embodiment has a configuration exemplified in FIG.
The optical monitoring device of this embodiment is an optical monitoring device that detects the intensity of light propagating through a plurality of incident side optical fibers 11,
a spatial optical system 30 that splits most of each incident light from an incident side optical fiber 11 into a specific first direction and the remainder into another specific second direction at a constant splitting ratio, and outputs each split light;
A plurality of incident side optical fibers 11 arranged in a two-dimensional array so as to input light to the spatial optical system 30;
A plurality of output side optical fibers 12 arranged to receive most of the light 42 output from the spatial optical system 30;
A light receiving unit 5 arranged to receive a part of light 43 emitted from the spatial optical system 30;
an incident-side optical lens 21 disposed between the spatial optical system 30 and the incident-side optical fiber 11, for converting each incident light from the incident-side optical fiber 11 to the spatial optical system 30 into a parallel light;
an output optical lens 22 that is disposed between the spatial optical system 30 and the output side optical fiber 12 and efficiently couples each output light from the spatial optical system 30 to the output side optical fiber 12 corresponding to the input side optical fiber 11;
has.

1 shows an example in which the specific angle is 45 degrees and the direction of the reflected light is 90 degrees, but the direction of the reflected light is not fixed at 90 degrees and can be changed as necessary. In addition, the spatial optical system 30 is not limited to a spatial system, and any optical component having a branching surface capable of branching into two light beams with different directions can be used.

1, the light from the incident side optical fiber 11 becomes parallel light at the incident side optical lens 21, preventing loss due to diffusion. Furthermore, most of the light 42 is guided to the output side optical lens 22 by the spatial optical system 30. The output side optical lens 22 collects the light that has passed through the spatial optical system 30 and couples it to the output side optical fiber 12. In this way, most of the light 42 emitted from the incident side optical fiber 11 can be guided to the output side optical fiber 12 with little loss.

On the other hand, a portion of the light 43 branched by the spatial optical system 30 is guided to the light receiving unit 5 arranged in a different direction from the majority of the light 42. The light receiving unit 5 has a light receiving surface large enough to receive all of the output light 43 from the spatial optical system 30. Light receiving elements, the number of which is greater than the number of incident side optical fibers 11, are two-dimensionally arranged on the light receiving surface of the light receiving unit 5. This makes it possible to measure the intensity of a portion of the light propagating from the incident side optical fiber 11 to the output side optical fiber 12.

2 illustrates the arrangement of the incident side optical fibers 11, and FIG. 3 illustrates the arrangement of the light receiving elements on the light receiving surface of the light receiving unit 5. M incident side optical fibers F1 to FM are arranged two-dimensionally with a fixed pitch of four. N light receiving elements M1 to MN are arranged two-dimensionally with a fixed pitch. In the present disclosure, the pitch of the incident side optical fibers F1 to FM and the pitch of the light receiving elements M1 to MN do not match, and no special alignment is performed. Therefore, when incident light 41 is incident from the incident side optical fiber F1, an image of the emitted light 43 from the incident side optical fiber F1 is formed on the light receiving surface of the light receiving unit 5, for example, as shown in FIG. 3. At this time, the emitted light 43 is detected by the light receiving elements M2 to M5, M15 to M18, M28 to M31, and M41 to M44. The light receiving section 5 detects the sum of the light intensities detected by the light receiving elements M2 to M5, M15 to M18, M28 to M31, and M41 to M44 as the light intensity of the outgoing light 43 from the incident side optical fiber F1.

Therefore, in the present disclosure, the light intensity of each of the light receiving elements M1 to MN when light of reference intensity Pr is emitted from the incident side optical fiber F1 is measured and recorded in advance. This makes it possible to obtain the correspondence relationships Or ₁₁ to Or _1N between the incident side optical fiber F1 and the light receiving elements M1 to MN. Similarly, for the incident side optical fibers F2 to FM, the correspondence relationships Or ₂₁ to Or _MN between the incident side optical fibers F2 to FM and the light receiving elements M1 to MN are recorded.

ここで、Ｏｒ_ｉｊは、入射側光ファイバＦ１～ＦＭのうちのｉ番目の光ファイバから光が出射されたときに、受光部５に備わるｊ番目の受光素子が受光した光強度である。 The correspondence between the incident side optical fibers F1 to FM and the light receiving elements M1 to MN can be expressed as follows.

Here, Or _ij is the light intensity received by the j-th light receiving element in the light receiving section 5 when light is emitted from the i-th optical fiber among the incident side optical fibers F1 to FM.

Next, if light having k ₁ to k _M times the reference intensity Pr is incident from the incident side optical fibers F1 to FM, respectively, the light intensities O ₁ to O _N detected by each light receiving element M1 to MN are the sum of the light incident from each optical fiber F1 to FM, and are expressed as shown in Equation 2.

Therefore, the intensity of the light incident on the light receiving section 5 from each of the optical fibers F1 to FM is expressed by Equation 3.

Since the branching ratio of the spatial optical system 30 is constant, for example, if it is K:1, it can be estimated that the light intensity incident from the input side optical fiber 11 is expressed by Equation 4, and the light intensity propagated to the output side optical fiber 12 is expressed by Equation 5.

The light intensity measurement method of the present disclosure includes:
The correspondence relationship represented by Equation 1 is acquired in advance,
While the incident optical fiber 11 is propagating light whose intensity is to be measured, the light receiving unit 5 measures the light intensity using Equation 3,
The intensity of the light incident on the input optical fiber 11 is measured using Equation 4.
The intensity of the light propagated to the output optical fiber 12 is measured using Equation 5.

The light intensity is measured by the light receiving unit 5 by detecting the light intensity received by each light receiving element when light is emitted from each incident side optical fiber 11. In this embodiment, the correspondence between the incident side optical fibers 11 and each light receiving element is acquired in advance. Therefore, the intensity of the light propagating through the incident side optical fibers 11 can be measured all at once based on the correspondence.

4, the spatial optical system 30 includes a monolayer film 33 having a uniform refractive index provided between an incident side member 30A and an exit side member 30B, both of which are made of a material having a uniform refractive index, and the monolayer film 33 is provided at a specific angle (45 degrees in the figure) with the optical axis of the incident light 41. As a result, a first refractive index interface 33A between the monolayer film 33 and the incident side member 30A and a second refractive index interface 33B between the monolayer film 33 and the exit side member 30B are each provided at a specific angle with the optical axis of the incident light.

When the incident side member 30A and the exit side member 30B have the same refractive index, the light beams 42B1 and 42B2 with different wavelengths travel in different directions in the single layer film 33. Therefore, the incident positions of the light beams 42B1 and 42B2 with different wavelengths on the refractive index interface 33B are different. On the other hand, the light beams incident from the refractive index interface 33B travel in the same direction as the incident side member 30A due to refraction between the single layer film 33 and the exit side member 30B. Therefore, even if the optical axes at the entrance end surfaces of the exit side optical fibers 12 are arranged in parallel, the transmitted light can be coupled to the exit side optical fibers 12 regardless of the wavelength.

In this manner, in the present disclosure, a difference in the incident position on the refractive index interface 33B occurs depending on the wavelength in the single layer film 33. Therefore, when the wavelengths of the output light 43B1 and 43B2 are different, the reflected position on the refractive index interface 33B is different for the output light 43B1 and 43B2. Therefore, in the present disclosure, the correspondence relationship expressed by Equation 1 may be obtained for each wavelength.

The position of the output optical lens 22 is determined according to the central wavelength and refraction angle of the incident light 41 and the thickness S of the single-layer film 33. The width of the light reaching the output optical lens 22 mainly depends on the wavelength width of the incident light 41 and the thickness S of the single-layer film 33. If the width of the light reaching the output optical lens 22 is small relative to the diameter of the output optical lens 22, the light loss is small, whereas if this width is large, the light loss is large. Therefore, the light loss can be reduced by setting the diameter of the output optical lens 22 to a value or more determined according to the wavelength width of the incident light 41 and the thickness S of the single-layer film 33. On the other hand, if the diameter of the output optical lens 22 is greater than the installation interval of the input fiber, the output optical lens 22 collides with the adjacent lens, so the diameter of the output optical lens 22 must be less than the installation interval of the input fiber.

(Effects of the present disclosure)
1, the input optical fiber 11 and the output optical fiber 12 are arranged two-dimensionally, and the two-dimensionally arranged light beam is split by the spatial optical system 30. This has the effect of making it possible to reduce the size of the device compared to using an optical monitor device for each single core or an optical monitor device in which optical fibers are arranged one-dimensionally. In addition, since the number of components is small, it is easy to reduce costs.

(Second embodiment)
FIG. 5 shows a second embodiment of the present disclosure. The incident side member 30A and the exit side member 30B can be made of a transparent material such as quartz glass. The single layer film 33 can be formed by placing a spacer 34 of a uniform predetermined thickness between the incident side member 30A and the exit side member 30B and opening a gap to utilize an air layer. The incident side optical lens 21 and the exit side optical lens 22 can be realized by a collimator in which a GRIN (GRADED INDEX) fiber is built into a rectangular ferrule used in optical connectors and the like. The incident side optical fiber 11 and the exit side optical fiber 12 are also built into rectangular ferrules 23 and 24, similar to the incident side optical lens 21 and the exit side optical lens 22, and the optical axes of the incident side optical fiber 11, the incident side optical lens 21, the exit side optical fiber 12, and the exit side optical lens 22 can be aligned using a guide pin 25 and a guide hole, similar to an optical connector. The light receiving unit 5 can be realized by a commercially available optical image sensor. By filling the connecting portion other than the single layer film 33 with a refractive index matching material, it is possible to suppress unnecessary Fresnel reflection.

The above are examples of the embodiment, but the present disclosure is not limited to these. For example, the single layer film 33 is an air layer, but the single layer film 33 may be glass having a lower refractive index than the incident side member 30A and the exit side member 30B. The spatial optical system 30 is not limited to a cubic shape, and may be any shape such as a rectangular parallelepiped. The light receiving unit 5 may be disposed at any position where the light branched by the spatial optical system 30 can be received. For example, the light receiving unit 5 may be embedded inside the spatial optical system 30.

The optical monitoring device of the present disclosure can be used to monitor any light transmitted in an optical transmission system. For example, the optical monitoring device of the present disclosure can be mounted in any device used in an optical transmission system, such as a transmitting device, a receiving device, or a repeater, and the measurement result at the light receiving unit 5 can be used for feedback or feedforward to any component inside or outside the device. Also, the optical monitoring device of the present disclosure can be inserted in the middle of a transmission line in an optical transmission system to measure the intensity and propagation loss of an optical signal in the transmission line.

The present disclosure can be applied to the information and communications industry.

5: Light receiving unit 11: Incident side optical fiber 12: Emitting side optical fiber 21: Incident side optical lens 22: Emitting side optical lenses 23, 24: Ferrule 25: Guide pin 30: Spatial optical system 30A: Incident side member 30B: Emitting side member 33: Single layer film 34: Spacer 41: Incident light 42: Most of the emitted light 43: Part of the emitted light

Claims (7)

An optical monitor device for detecting the intensity of light propagating through a plurality of optical fibers, comprising:
an optical component that splits a part of the incident light from the plurality of optical fibers in a first direction and the rest in a second direction at a constant split ratio and outputs the split light;
a light receiving unit that receives light emitted from the optical component in a second direction;
Equipped with
The light receiving unit is
a light receiving surface having a size capable of receiving all of the light emitted from the optical component in the second direction;
a number of light receiving elements greater than the number of the optical fibers are two-dimensionally arranged on the light receiving surface;
one or more of the light receiving elements of the light receiving unit receive incident light from two or more of the optical fibers of the plurality of optical fibers ;
measuring the light intensity of each of the plurality of optical fibers simultaneously incident thereon ;
Optical monitor device. The optical component is
a single-layer film having a uniform thickness and splitting a part of the incident light in the first direction and the remainder in the second direction at a constant splitting ratio;
an incident side member provided on an incident side of the monolayer film and having a refractive index different from that of the monolayer film;
an exit side member provided on the exit side of the single layer film and having the same refractive index as the entrance side member;
Equipped with
a first refractive index interface between the single layer film and the incident side member and a second refractive index interface between the single layer film and the output side member are provided at specific angles with respect to an optical axis of the incident light,
2. The optical monitor device according to claim 1 . the plurality of optical fibers are a plurality of incident side optical fibers that are two-dimensionally arranged so as to introduce light into the optical component;
a plurality of output side optical fibers arranged two-dimensionally so as to receive each output light from the optical component in the first direction;
an incident-side optical lens disposed between the optical component and the incident-side optical fiber, and converting each light beam incident on the optical component into a parallel beam;
an output optical lens disposed between the optical component and the output optical fiber, for coupling each output light from the optical component to the output optical fiber;
3. The optical monitor device according to claim 1, further comprising: a splitting ratio between the first direction and the second direction in the optical component is K:1;
The correspondence relationship between the light intensity received by each of the N light receiving elements when light of the reference intensity Pr is emitted from the M optical fibers is expressed by Equation C11,
Measure the light intensity received by the light receiving unit for each of the plurality of optical fibers when light having k times the reference intensity Pr is incident from at least any one of the M number of optical fibers, using formula C12.
4. An optical monitor device according to claim 1.

Here, _Orij is the light intensity received by the jth light receiving element of the light receiving unit when light with light intensity Pr is emitted from the ith optical fiber of the plurality of optical fibers, and _Oj is the light intensity detected by the jth light receiving element when light k _i times the reference intensity Pr is incident from the ith optical fiber of the plurality of M optical fibers. a splitting ratio between the first direction and the second direction in the optical component is K:1;
The correspondence relationship between the light intensity Pr received by each of the N light receiving elements when light having a reference intensity Pr is emitted from the M optical fibers is expressed by Equation C21,
When light having a light intensity k times the reference intensity Pr is incident from at least one of the M optical fibers, the light intensity of the incident light for each of the optical fibers is measured using Equation C22.
4. An optical monitor device according to claim 1.

Here, _Orij is the light intensity received by the jth light receiving element of the light receiving unit when light with light intensity Pr is emitted from the ith optical fiber of the plurality of optical fibers, and _Oj is the light intensity detected by the jth light receiving element when light k _i times the reference intensity Pr is incident from the ith optical fiber of the plurality of M optical fibers. a splitting ratio between the first direction and the second direction in the optical component is K:1;
The correspondence relationship between the light intensity received by each of the N light receiving elements when light of the reference intensity Pr is emitted from the M optical fibers is expressed by Equation C31,
Measure the light intensity of the output light from each of the plurality of optical fibers when light having a light intensity k times the reference intensity Pr is input from at least any one of the M number of optical fibers, using Equation C32.
4. An optical monitor device according to claim 1.

Here, _Orij is the light intensity received by the jth light receiving element of the light receiving unit when light with light intensity Pr is emitted from the ith optical fiber of the plurality of optical fibers, and _Oj is the light intensity detected by the jth light receiving element when light k _i times the reference intensity Pr is incident from the ith optical fiber of the plurality of M optical fibers. 7. A light intensity measuring method for collectively measuring the intensity of light propagating through a plurality of optical fibers using the optical monitor device according to claim 1, comprising:
measuring a received light intensity at each light receiving element when the light is emitted from each of the plurality of optical fibers, thereby obtaining a correspondence relationship between the plurality of optical fibers and each light receiving element in advance;
Detecting the light intensity of each light receiving element received by the light receiving unit while the plurality of optical fibers are propagating light to be measured;
Based on the correspondence relationship, for each of the plurality of optical fibers,
(i) the light intensity received by the light receiving unit;
(ii) the light intensity of the incident light ;
(iii) the light intensity of the emitted light ;
Measure at least one of the following:
Light intensity measurement methods.

Images