WO2022249456A1

WO2022249456A1 - Optical monitoring device and light intensity measurement method

Info

Publication number: WO2022249456A1
Application number: PCT/JP2021/020452
Authority: WO
Inventors: 良小山; 宜輝阿部; 和典片山
Original assignee: 日本電信電話株式会社
Priority date: 2021-05-28
Filing date: 2021-05-28
Publication date: 2022-12-01
Also published as: JPWO2022249456A1

Abstract

The purpose of the present disclosure is to reduce the size and cost of an optical monitoring device for detecting the intensity of light propagating through optical fibers.　The present disclosure is an optical monitoring device for detecting the intensity of light propagating through a plurality of optical fibers (11), said device comprising: an optical component (30) that branches, at a fixed branching ratio, a portion of incident light from the plurality of optical fibers (11) in a first direction, and the rest in a second direction, and that emits the branched light; and a light receiving part (5) that receives the light emitted in the second direction from the optical component (30). The light receiving part (5) has a light receiving surface of a size capable of receiving all the light emitted in the second direction from the optical component (30), and has light receiving elements in a number greater than the optical fibers, which are arranged two-dimensionally on the light receiving surface.

Description

Optical monitor device and optical intensity measurement method

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

In recent years, with the increase in Internet traffic, there is a strong demand for increased communication capacity in communication systems. In order to achieve this, a communication system using optical fibers is used in the access network between the communication office and the user's home and in the core network connecting the communication office. Optical fiber communication often uses the detection of the intensity of light propagating through an optical fiber to control communication and confirm the soundness of equipment. For example, in an access network, test light is propagated through an optical fiber, and the optical intensity is detected to check the loss and soundness of the optical fiber, as well as the target and connection of the core wires. In addition, WDM (Wavelength Division Multiplexing) transmission used in core networks requires monitoring of optical intensity for feedback control.

For optical intensity monitoring of access networks, the technology described in Patent Document 1, for example, is used. Patent Literature 1 describes a technique for splitting light at a constant splitting ratio using two parallel waveguides, which makes it possible to measure the intensity and propagation loss of optical signals in an access network.

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

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

With the spread of optical communication, the number of optical fibers in optical equipment/optical cables is increasing. Increase in size. Even in the case of optical monitoring devices in which optical fibers and light intensity sensors are arranged in a one-dimensional array, there is a limit to the arrangement of optical fibers in the array. increases cost and size.

Also, the optical fiber and the light intensity sensor correspond one-to-one, and it is necessary to arrange the sensor and the optical fiber at the same pitch. Furthermore, it is necessary to precisely position the optical fiber so that the light from the optical fiber is incident on the sensor.

Patent No. 3450104 (Furukawa Electric) Japanese Patent Application Laid-Open No. 2004-219523 (Fujitsu, withdrawn)

The present disclosure has been made in view of these points, and aims to provide a compact optical monitor device with several tens of cores that can be manufactured at low cost.

The optical monitor device of the present disclosure comprises:
In an optical monitoring device that detects the intensity of light propagating through multiple optical fibers,
an optical component for branching 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 branching ratio, and
a light-receiving unit that receives light emitted from the optical component in a second direction;
with
The light receiving unit is
having a light receiving surface large enough to receive all of the light emitted from the optical component in the second direction;
More light receiving elements than the optical fibers are arranged two-dimensionally on the light receiving surface.

The light intensity measurement method of the present disclosure includes
A light intensity measuring method for collectively measuring the intensity of light propagating through a plurality of optical fibers using the optical monitor device of the present disclosure,
obtaining in advance the correspondence relationship between the plurality of optical fibers and each light receiving element by measuring the light receiving intensity at each light receiving element when each optical fiber is emitted from the plurality of optical fibers,
Detecting the light intensity of each light receiving element received by the light receiving unit in a state where the plurality of optical fibers are propagating the light whose intensity is to be measured,
Based on the correspondence relationship, for each of the plurality of optical fibers,
(i) intensity of light received by the light receiving unit;
(ii) light intensity of incident light incident from the plurality of incident-side optical fibers;
(iii) the light intensity of the output light emitted to the plurality of output-side optical fibers;
measure at least one of

According to the present disclosure, since light is received using a light receiving unit in which light receiving elements larger than the number of optical fibers are arranged two-dimensionally on the light receiving surface, an optical monitoring device for optical fibers with a large number of fibers, such as several tens of fibers, can be used. can be realized in a small size and at a low cost. Further, according to the present disclosure, highly accurate positioning of the light receiving element is not required.

1 illustrates an example embodiment of an optical monitoring device of the present disclosure; An example of the arrangement of incident-side optical fibers is shown. 4 shows an example of arrangement of light receiving elements in a light receiving section. An example of light propagating through a spatial optical system is shown. 1 illustrates an example embodiment of an optical monitoring device of the present disclosure;

Hereinafter, 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 modified and improved forms based on the knowledge of those skilled in the art. In addition, in this specification and the drawings, constituent elements having the same reference numerals are the same as each other.

(First embodiment example)
The optical monitor device of this embodiment has the configuration illustrated 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,
For each incident light from the incident side optical fiber 11, most of the incident light is branched in a specific first direction and the rest is branched in another specific second direction at a constant branching ratio, and each branched light a spatial optical system 30 for emitting the
a plurality of incident-side optical fibers 11 arranged in a two-dimensional array so that light is incident on the spatial optical system 30;
a plurality of output-side optical fibers 12 arranged to receive most of the light 42 emitted from the spatial optical system 30;
a light receiving unit 5 arranged to receive a part of the 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 to convert each incident light from the incident-side optical fiber 11 to the spatial optical system 30 into parallel light;
Output-side optics arranged between the spatial optical system 30 and the output-side optical fiber 12 for efficiently coupling each output light from the spatial optical system 30 to the output-side optical fiber 12 corresponding to the incident-side optical fiber 11 a lens 22;
have

Although FIG. 1 shows an example in which the specific angle is 45 degrees and the direction of reflected light is 90 degrees, the direction of reflected light is not fixed at 90 degrees and can be changed as needed. Further, 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 in different directions can be used.

According to the optical monitor device illustrated in FIG. 1, light from the incident side optical fiber 11 becomes parallel light at the incident side optical lens 21, and loss due to diffusion is prevented. Furthermore, most of the light 42 is guided to the output side optical lens 22 by the spatial optical system 30 . The exit-side optical lens 22 collects the light that has passed through the spatial optical system 30 and couples it to the exit-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 emitting side optical fiber 12 with little loss.

On the other hand, part of the light 43 split by the spatial optical system 30 is guided to the light receiving section 5 arranged in a direction different from that of the majority of the light 42 . The light receiving section 5 has a light receiving surface large enough to receive all the emitted light 43 from the spatial optical system 30 . On the light-receiving surface of the light-receiving unit 5, light-receiving elements larger in number than the incident-side optical fibers 11 are arranged two-dimensionally. Thereby, the intensity of part of the light propagating from the incident side optical fiber 11 to the emitting side optical fiber 12 can be measured.

2 illustrates the arrangement of the incident-side optical fiber 11, and FIG. 3 illustrates the arrangement of the light receiving elements on the light receiving surface of the light receiving section 5. FIG. M incident-side optical fibers F1 to FM are arranged two-dimensionally at a constant pitch of four. N light receiving elements M1 to MN are two-dimensionally arranged at a constant pitch. In the present disclosure, the pitch of the incident side optical fibers F1 to FM does not match the pitch of the light receiving elements M1 to MN, and no special alignment is performed. On the light receiving surface of the portion 5, an image of the outgoing light 43 of the incident side optical fiber F1 is formed as shown in FIG. 3, for example. 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 unit 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 emitted 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 the light of the reference intensity Pr is emitted from the incident side optical fiber F1 is measured in advance and recorded. As a result, the correspondences Or ₁₁ to Or _1N between the incident-side optical fiber F1 and the light receiving elements M1 to MN can be obtained. Similarly, for the incident side optical fibers F2 to FM, the corresponding 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.

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 provided in the light-receiving unit 5 when the light is emitted from the i-th optical fiber among the incident-side optical fibers F1 to FM.

Next, assuming that light with k ₁ to _kM 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 the light receiving elements M1 to MN are Since it is the sum of the light incident from F1 to FM, it is represented by Equation 2.

Therefore, the intensity of 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, the intensity of the light incident from the incident side optical fiber 11 is given by Equation 4, and the intensity of the light propagated to the outgoing side optical fiber 12 is given by Equation 4. 5 can be estimated.

The light intensity measurement method of the present disclosure includes
Acquire in advance the correspondence represented by Equation 1,
While the incident-side optical fiber 11 is propagating the light whose intensity is to be measured, the light intensity is measured by the light receiving unit 5 using Equation 3,
Measure the light intensity incident from the incident side optical fiber 11 using Equation 4,
Using Equation 5, the intensity of light propagated to the output side optical fiber 12 is measured.

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

Furthermore, in the optical monitor device of the present embodiment, as shown in FIG. 4, the spatial optical system 30 is provided between the entrance-side member 30A and the exit-side member 30B made of a material with a uniform refractive index. Another single-layer film 33 having a uniform refractive index is provided, and the single-layer film 33 is provided at a specific angle (45 degrees in the figure) with respect to the optical axis of the incident light 41 . As a result, the first refractive index interface 33A between the single layer film 33 and the entrance side member 30A and the second refractive index interface 33B between the single layer film 33 and the exit side member 30B are specified as the optical axis of the incident light. is set at an angle of

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

As described above, in the present disclosure, the single-layer film 33 causes a difference in the incident position to the refractive index interface 33B depending on the wavelength. Therefore, when the emitted lights 43B1 and 43B2 have different wavelengths, the emitted lights 43B1 and 43B2 have different reflection positions at the refractive index interface 33B. Therefore, in the present disclosure, the correspondence represented by Equation 1 may be obtained for each wavelength.

In addition, the position of the output-side optical lens 22 is determined according to the center wavelength and refraction angle of the incident light 41 and the thickness S of the single layer film 33 . Furthermore, the width of the light reaching the output side 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-side optical lens 22 is small with respect to the diameter of the output-side optical lens 22, the light loss is small. Therefore, by setting the diameter of the exit-side optical lens 22 to a value equal to or larger than the value determined according to the wavelength width of the incident light 41 and the thickness S of the single-layer film 33, the optical loss can be reduced. On the other hand, if the diameter of the output-side optical lens 22 is greater than or equal to the installation interval of the incident-side fibers, it collides with the adjacent lens. .

(Effect of the present disclosure)
According to the optical monitor device illustrated in FIG. 1, the incident-side optical fiber 11 and the output-side optical fiber 12 are two-dimensionally arranged, and the spatial optical system 30 splits the two-dimensionally arranged light flux. As a result, there is an effect that the size can be reduced more than using an optical monitoring device for each single fiber or an optical monitoring device in which optical fibers are arranged one-dimensionally. In addition, there is an effect that the cost can be easily reduced because the number of constituent parts is small.

(Second embodiment example)
FIG. 5 shows a second example embodiment of the present disclosure. The entrance 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 utilize an air layer by arranging a spacer 34 having a uniform predetermined thickness between the incident-side member 30A and the emitting-side member 30B to form a gap. The incident-side optical lens 21 and the output-side optical lens 22 can be realized by a collimator in which a GRIN (GRaded INdex) fiber is incorporated in a rectangular ferrule used in an optical connector or the like. The incident-side optical fiber 11 and the output-side optical fiber 12 are also incorporated in the

rectangular ferrules

23 and 24 similarly to the incident-side optical lens 21 and the output-side optical lens 22, and the guide pins 25 and the guide holes are used as in the optical connector. 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. The light receiving section 5 can be realized by a commercially available optical image sensor. By filling the connection portion other than the single layer film 33 with a refractive index matching material, unnecessary Fresnel reflection can be suppressed.

The above is an example embodiment, but it is not limited to this. For example, although an example in which the single layer film 33 is an air layer is shown in the present disclosure, the single layer film 33 may be glass having a lower refractive index than the incident side member 30A and the output side member 30B. Moreover, the spatial optical system 30 is not limited to a cubic shape, and may have any shape such as a rectangular parallelepiped. Also, the light receiving section 5 can be arranged at any position where the light branched by the spatial optical system 30 can be received. For example, the light receiving section 5 may be embedded inside the spatial optical system 30 .

Also, the optical monitoring device of the present disclosure can be used for monitoring any light transmitted in an optical transmission system. For example, the optical monitoring device of the present disclosure is installed in any device used in an optical transmission system, such as a transmitter, a receiver, or a relay device, and the measurement result at the light receiving unit 5 is measured at any part inside or outside the device. can be used for feedback or feedforward to Also, the optical monitor 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.

This disclosure can be applied to the information and communications industry.

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

Claims

In an optical monitoring device that detects the intensity of light propagating through multiple optical fibers,
an optical component for branching 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 branching ratio, and
a light-receiving unit that receives light emitted from the optical component in a second direction;
with
The light receiving unit is
having a light receiving surface large enough to receive all of the light emitted from the optical component in the second direction;
More light-receiving elements than the optical fibers are arranged two-dimensionally on the light-receiving surface,
Optical monitor device.
The optical component is
a single-layer film having a uniform thickness and branching part of the incident light in the first direction and the rest in the second direction at a constant branching ratio;
an incident-side member provided on the incident side of the single-layer film and having a refractive index different from that of the single-layer film;
an output-side member provided on the output side of the single-layer film and having the same refractive index as that of the incident-side member;
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 exit side member are provided at specific angles with respect to the optical axis of the incident light. ing,
2. The optical monitor device of claim 1, wherein:
the plurality of optical fibers are a plurality of incident-side optical fibers arranged two-dimensionally so as to allow light to enter the optical component;
a plurality of exit-side optical fibers arranged two-dimensionally so as to receive respective beams of light emitted from the optical component in the first direction;
an incident-side optical lens disposed between the optical component and the incident-side optical fiber to convert each incident light beam to the optical component into parallel light;
an output-side optical lens disposed between the optical component and the output-side optical fiber for coupling each output light from the optical component to the output-side optical fiber;
3. An optical monitoring device according to claim 1 or 2, comprising:
a branching 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 the light of the reference intensity Pr is emitted from the plurality of M optical fibers is expressed by Equation C11,
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 one of the M optical fibers; , as measured using Equation C12,
4. An optical monitor device according to any of claims 1-3.

However, Or ij is the light intensity received by the j-th light receiving element provided in the light-receiving unit when the light with the light intensity Pr is emitted from the i-th optical fiber among the plurality of optical fibers. Further, Oj is the light intensity detected by the j-th light receiving element when light having k i times the reference intensity Pr is incident from the i-th optical fiber out of the plurality of M optical fibers. is.
a branching 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 the light of the reference intensity Pr is emitted from the plurality of M optical fibers is represented by the formula C21,
When light having k times the reference intensity Pr is incident from at least one of the M optical fibers, the light is incident from the plurality of incident side optical fibers for each of the plurality of optical fibers. Measure the light intensity of the incident light using the formula C22,
5. An optical monitor device according to any of claims 1-4.

However, Or ij is the light intensity received by the j-th light receiving element provided in the light-receiving unit when the light with the light intensity Pr is emitted from the i-th optical fiber among the plurality of optical fibers. Further, Oj is the light intensity detected by the j-th light receiving element when light having k i times the reference intensity Pr is incident from the i-th optical fiber out of the plurality of M optical fibers. is.
a branching 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 the light of the reference intensity Pr is emitted from the plurality of M optical fibers is represented by the formula C31,
When light having k times the reference intensity Pr is incident from at least one of the M optical fibers, it is emitted to the plurality of output side optical fibers for each of the plurality of optical fibers. Measure the light intensity of the emitted light using the equation C32,
6. An optical monitor device according to any of claims 1-5.

However, Or ij is the light intensity received by the j-th light receiving element provided in the light-receiving unit when the light with the light intensity Pr is emitted from the i-th optical fiber among the plurality of optical fibers. Further, Oj is the light intensity detected by the j-th light receiving element when light having k i times the reference intensity Pr is incident from the i-th optical fiber out of the plurality of M optical fibers. is.
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 any one of claims 1 to 6,
obtaining in advance the correspondence relationship between the plurality of optical fibers and each light receiving element by measuring the light receiving intensity at each light receiving element when each optical fiber is emitted from the plurality of optical fibers,
Detecting the light intensity of each light receiving element received by the light receiving unit in a state where the plurality of optical fibers are propagating the light whose intensity is to be measured,
Based on the correspondence relationship, for each of the plurality of optical fibers,
(i) intensity of light received by the light receiving unit;
(ii) light intensity of incident light incident from the plurality of incident-side optical fibers;
(iii) the light intensity of the output light emitted to the plurality of output-side optical fibers;
measuring at least one of
Light intensity measurement method.