JP2005037669A - Optical branching element, optical branching element unit, optical branching device, and wavelength multiplex optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical branching element which is capable of suppressing diffusion of branched signal light and also reducing polarization dependency of an optical element for receiving the branched signal light, and to provide an optical branching element unit, an optical branching device, and a wavelength multiplex optical transmission sytem. <P>SOLUTION: The optical branching element 1 has an optical circuit 2, and an optical circuit 3 obliquely fixed on the top face part of this optical circuit 2. The optical circuit 2 has an end face S<SB>1</SB>inclined at a predetermined tilt angle α(degree) to a vertical axis L<SB>2</SB>orthogonal to the optical axis L<SB>1</SB>of an optical fiber 5. And, on the surface of the end face S<SB>1</SB>, a reflecting filter 6 for reflecting a part of the signal light to be transmitted through the optical fiber 5 with a predetermined reflectance is provided. On the other hand, the optical circuit 3 is so arranged that the optical element is connected to one side end part thereof and the other side end part is formed with an end face S<SB>2</SB>at an end face tilt angle β(degree). The end face S<SB>2</SB>is fixed on the surface of a clad part 5b in the optical fiber 5 of the optical fiber 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical branching device, an optical branching device unit, an optical branching device, and a wavelength division multiplexing optical transmission system for branching signal light transmitted through an optical waveguide such as an optical fiber or a planar optical waveguide.

As a device for branching signal light transmitted through an optical waveguide such as an optical fiber or a planar optical waveguide, a device described in Patent Document 1 below is known. The optical device described in Patent Document 1 has a substrate on which an optical fiber for transmitting signal light is fixed, and a signal transmitted through the optical fiber is placed in a groove formed in the optical fiber together with the substrate. An optical member having a surface that reflects or diffracts at least part of the light (hereinafter referred to as a reflection filter) is inserted and bonded. On the substrate, an optical element such as a photodetector for monitoring signal light branched by being reflected by the reflection filter (hereinafter referred to as branched light) is disposed.
JP 2001-66473 A

  However, in the optical device described in Patent Document 1, the reflection filter is bonded to the groove with resin, and a large amount of resin is interposed between the reflection filter and the photodetector. Accordingly, the branched light passes through the resin and enters the photodetector, but may be diffused when passing through the resin. When the branched light is diffused, if a plurality of optical fibers are juxtaposed, crosstalk occurs between adjacent photodetectors.

  In addition, in the optical device described in Patent Document 1, since the branched light is incident at an angle with respect to the light incident surface of the photodetector disposed on the substrate, the polarization of the light transmitted through the light incident surface is deviated. Due to the wave dependency, there arises a problem that the light receiving sensitivity of the branched light at the photodetector changes depending on the polarization state of the signal light.

  An object of the present invention is to provide an optical branching element, an optical branching element unit, an optical branching device, and an optical branching element capable of suppressing the diffusion of the branched signal light and reducing the polarization dependence of the optical element that receives the branched signal light. It is to provide a wavelength division multiplexing optical transmission system.

  An optical branching element according to the present invention includes a first optical circuit including a first optical waveguide having an end surface inclined with respect to a vertical axis orthogonal to the optical axis, and one of signal light transmitted through the first optical waveguide. A reflection filter that reflects the part with a predetermined reflectance, and a second optical waveguide that is fixed obliquely to the first optical circuit and that transmits the light branched by reflecting the signal light by the reflection filter. And a second optical circuit.

  According to the present invention, since the second optical circuit is optically connected to the first optical circuit, the signal light branched by being reflected by the reflection filter reaches the second optical waveguide from the first optical waveguide. It is possible to suppress diffusion during the process. In addition, when an optical element such as a photodetector that receives the branched signal light is applied, the optical element can be connected perpendicularly to the second optical circuit, so that the branched signal light is directed to the incident surface of the optical element. Thus, it is possible to make the light incident vertically. For this reason, the polarization dependence of the optical element can be reduced.

  In this case, at least one of the first optical circuit and the second optical circuit may be a planar optical waveguide type optical circuit. Thereby, since it becomes possible to use a thin substrate compared with the case of an optical fiber, the whole optical branching element can be reduced in size. Further, when the first optical circuit is a planar optical waveguide type optical circuit, since the upper surface is flat, it is easy to align and fix the second optical circuit.

  Further, at least one of the first optical waveguide and the second optical waveguide may be an optical fiber. Thereby, an input / output optical fiber, a measuring instrument, etc. can be easily connected using fusion splicing or connector connection.

  Preferably, the second optical circuit is fixed to a side surface of the first optical circuit via a resin. Thereby, since the space around the optical fiber is filled with the resin, scattering of the branched light can be prevented. Note that it is desirable to use a resin whose refractive index is adjusted.

  In the first optical circuit, an optical fiber is fixed to the array substrate, and an optically transparent plate disposed opposite the array substrate is disposed on the opposite side of the array member with respect to the optical fiber. Provided, and the optical fiber and the second optical circuit may be fixed via the plate. Such a plate preferably has a smooth surface. Thereby, since the part to which the second optical circuit is fixed becomes a flat and smooth surface, irregular reflection of the branched light can be suppressed.

  The first optical circuit has an optical fiber fixed to the array substrate, the second optical circuit is fixed to the clad of the optical fiber, and the portion to which the second optical circuit of the clad is fixed is an optical fiber. The distance between the fiber core and the second optical circuit may be shorter than the radius of the optical fiber. Thereby, since the part which fixes a 2nd optical circuit becomes a flat surface, the irregular reflection of the branched light can be suppressed. In addition, since the distance between the optical fiber of the first optical circuit and the second optical waveguide of the second optical circuit is shortened, the light reflected by the reflection filter can be efficiently introduced into the second optical waveguide. The cladding is preferably polished by polishing in order to increase the surface smoothness.

  The first optical circuit has N (N is a plurality) first optical waveguides, and the second optical circuit has N second optical waveguides corresponding to the N first optical waveguides, respectively. In the first optical circuit, an optical fiber is fixed to the array substrate, and at least one of the adjacent optical fibers is preferably provided with a partition wall. This prevents the light reflected by the reflection filter from entering the adjacent second optical waveguide that should not be incident other than the corresponding second optical waveguide due to the influence of scattering or the like. it can.

  In this case, the second optical circuit is fixed to the clad of the optical fiber, and the portion where the second optical circuit of the clad is fixed is such that the distance between the core of the optical fiber and the second optical circuit is shorter than the radius of the optical fiber. It is preferable to be formed as follows. Thereby, since the distance between the optical fiber of the first optical circuit and the second optical waveguide of the second optical circuit is shortened, the light reflected by the reflection filter can be efficiently introduced into the second optical waveguide.

  Preferably, the partition wall includes a positioning substrate having a groove formed on a first surface thereof, the groove being engaged with an optical fiber fixed to the array substrate, and a second core and an optical fiber core. It is formed by removing from the second surface located on the opposite side of the first surface so that the distance to the optical circuit is equal to or less than the radius of the optical fiber. Thereby, the said partition can be provided between adjacent optical fibers in the state which positioned the optical fiber with high precision.

  A third optical circuit that is disposed on the opposite side of the first optical circuit with respect to the reflection filter, and includes a third optical waveguide that transmits the signal light transmitted through the reflection filter and transmitted through the reflection filter; Prepare. Thereby, for example, a planar optical waveguide having an end face whose inclination angle does not coincide with the end face of the first optical waveguide can be applied.

  The third optical circuit may be a planar optical waveguide type optical circuit. The third optical waveguide may be an optical fiber.

  In this case, it is preferable that the reflection filter is provided on the end face of the third optical waveguide, and the first optical circuit and the third optical circuit are fixed via the reflection filter. For example, when a reflection filter is formed by vapor deposition on the end face of a first optical circuit in which the first optical waveguide is an optical fiber, the workability is poor because it is affected by the routing of the optical fiber. Therefore, if a reflective filter is vapor-deposited on the third optical circuit, such an influence is reduced, so that the reflective filter can be formed with good workability.

  The optical branching element unit of the present invention includes two of the above-described optical branching elements, and the two optical branching elements are joined to each other at positions opposite to the second optical circuit with respect to the first optical circuit. It is characterized by being integrated. Thereby, it is possible to increase the density of the portion where the signal light branches without taking up a space in the arrangement direction of the optical path of the optical waveguide.

  An optical branching device according to the present invention includes a first optical circuit including a first optical waveguide having an end face inclined with respect to a vertical axis orthogonal to the optical axis, and one of signal light transmitted through the first optical waveguide. A second optical circuit configured to include a reflection filter that reflects the part with a predetermined reflectance, a second optical waveguide that transmits the light branched when the signal light is reflected by the reflection filter, and the second light And an optical element connected to the circuit and receiving the branched light transmitted through the second optical waveguide.

  According to the present invention, since the second optical circuit is optically connected to the first optical circuit, the second part of the second optical circuit is not diffused without most of the signal light reflected and branched off by the reflection filter. Incident into the optical waveguide. In addition, since the second optical circuit is connected to the optical element that receives the branched signal light, the branched signal light reflected by the reflection filter can be incident perpendicularly to the incident surface of the optical element. Become. Therefore, since the polarization dependency of the optical element is reduced, the light receiving sensitivity can be improved.

  Further, the present invention is a wavelength division multiplexing optical transmission system that performs optical transmission by multiplexing multi-wavelength signal light, and is characterized by including the above optical branching element. Thereby, as described above, it is possible to suppress the diffusion of the branched signal light and reduce the polarization dependency of the optical element that receives the branched signal light.

  According to the present invention, since the optical waveguide through which the branched signal light is transmitted is connected to the optical waveguide through which the signal light is transmitted, it is possible to suppress the diffusion of the branched signal light and to receive the branched signal light. It is possible to provide an optical branching element, an optical branching element unit, an optical branching device, and a wavelength division multiplexing optical transmission system that can reduce the polarization dependency of the element.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.
[First Embodiment]
Fig.1 (a) is sectional drawing which shows the optical branching element concerning the 1st Embodiment of this invention, FIG.1 (b) is the II arrow directional view of Fig.1 (a). In FIG. 1, the optical branching element 1 has an optical circuit 2 and an optical circuit 3 that is obliquely connected to the upper surface of the optical circuit 2.

The optical circuit 2 has an array substrate 4 made of quartz, pyrex, silicon or the like, and a plurality of optical fibers 5 are arrayed and fixed on the upper surface of the array substrate 4. The optical circuit 2 has an end face S ₁ that is inclined at a predetermined inclination angle (hereinafter referred to as an end face angle) α (degrees) with respect to a vertical axis L ₂ orthogonal to the optical axis L ₁ of the optical fiber 5. Yes. A reflection filter 6 is provided on the surface of the end face S ₁ . The reflection filter 6 is composed of a dielectric multilayer filter or the like, and reflects part of the signal light transmitted through the optical fiber 5 with a predetermined reflectance. The reflection filter 6 may be attached to the surface of the end surface S ₁ with an adhesive such as a resin, or may be formed by vapor deposition.

On the other hand, the optical circuit 3 includes an array substrate 7 formed of quartz, pyrex, silicon, or the like, and a plurality of optical fibers 8 are fixed to the upper surface portion of the array substrate 7. Such an optical circuit 3 is configured such that an optical element such as a photodiode is connected to one end of the optical fiber 8. An end face S ₂ having an end face angle β (degrees) is formed at the other end of the optical fiber 8 and the end of the array substrate 7, and this end face S ₂ is the optical fiber 5 of the optical circuit 2. Is fixed to the surface of the clad portion 5b. In this state, the optical circuit 2 and the optical circuit 3 are bonded by, for example, a resin 9 that optically matches the optical fiber. Thereby, since the space around the optical fiber 5 is filled with the resin 9, scattering of the branched light is prevented. As the resin 9, an acrylic resin, an epoxy resin, a silicone resin, or the like is used. Note that “optically matching” in the present embodiment means that the refractive index is close to the core portion (first optical waveguide) 5a of the optical fiber. Further, the optical circuit 2 and the optical circuit 3 may be connected using fusion splicing, welding, or an adhesive. As the adhesive, it is desirable to use a UV curable type.

  The optical fiber 8 of the optical circuit 3 is configured to transmit the light branched by being reflected by the reflection filter 6 out of the signal light transmitted through the optical fiber 5. Therefore, the end face angle β is desirably 90-2α (degrees) or a value close thereto. For example, α is about 20 degrees.

In the optical branching element 1 as described above, part of the signal light transmitted through the optical fiber 5 is branched by being reflected by the reflection filter 6. At this time, since the end face of the optical fiber 8 of the optical circuit 3 is fixed to the optical fiber 5 of the optical circuit 2, most of the branched light is light as shown by an arrow A in FIG. The light passes through the cladding 5 b of the fiber 5 and enters the core (second optical waveguide) 8 a of the optical fiber 8. Therefore, it is possible to suppress the diffusion of the branched light and prevent the incident light from entering the adjacent optical fiber 8. Further, since the optical fiber 8 of the optical circuit 3 can be connected perpendicularly to the incident surface of an optical element such as a photodetector, for example, the signal light branched by being reflected by the reflection filter 6 is optically transmitted. The light can enter perpendicularly to the incident surface of the element. Therefore, the polarization dependency of the optical element can be reduced.
[Second Embodiment]
FIG. 2A is a cross-sectional view showing an optical branching element according to the second embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line II-II in FIG. The optical branching element 10 according to the present embodiment is different from the optical branching element 1 shown in FIG. 1 in the fixing part between the optical circuit 2 and the optical circuit 3.

In the optical branching element 10, the optical fiber 5 of the optical circuit 2 is fixed to the optical circuit 3 through a resin 9. A part of the resin 9 is removed by being polished or ground or melted at a portion where the optical circuit 3 is fixed. Thus, the layer of resin 9 in the portion where the optical circuit 3 is fixed is thinner than the layer at a site other than that, the distance between the end face S ₂ of the core portion 8a and the light circuit 3 of the optical fiber 5 is short . Further, since the surface of the resin 9 on which the optical circuit 3 is fixed is flat and smooth, it is possible to suppress irregular reflection of light and the like. Thus, compared with a case where without removing the portion of the resin 9 for fixing the end face S ₂ of the optical fiber 5 and the optical circuit 3, thereby introducing the light reflected by the reflection filter 6 efficiently optical fiber 8 Can do.
[Third Embodiment]
Fig.3 (a) is sectional drawing which shows the optical branching element which concerns on the 3rd Embodiment of this invention, FIG.3 (b) is the III-III arrow directional view of Fig.3 (a). The optical branching element 20 according to the present embodiment is different from the above-described optical branching elements 1 and 10 in the fixing portion between the optical circuit 2 and the optical circuit 3.

The optical branching element 20 includes a plate 21 disposed opposite to the array substrate 4 on the upper surface side of the optical circuit 2, that is, on the opposite side of the array substrate 4 with respect to the optical fiber 5. The plate 21 is optically transparent and is made of, for example, quartz or pyrex. Then, on the opposite side of the optical circuit 2 to the plate 21, and the end face S ₂ of the optical circuit 3 is connected, after transmitting through the optical fiber 5, branched by being reflected by the reflection filter 6 Light is transmitted through the optical fiber 8 of the optical circuit 3.

In such an optical branching element 20, after the optical fibers 5 are arranged on the array substrate 4, a plate 21 is placed on the optical fiber 5, and the resin 11 is injected into a region between the array substrate 4 and the plate 21. And fix. Then, the plate 21 and the end face S ₁ of the optical circuit 3 are bonded by a resin or the like (not shown) that optically matches the optical fiber. As this resin, an acrylic resin, an epoxy resin, a silicone resin, or the like is used. The resin 11 for fixing the optical fiber 5 to the array substrate 4 may not be optically matched. The resin used as the adhesive is preferably cured by UV light (ultraviolet light), and more preferably filled with quartz or mica filler.

In the optical branching device 20 according to the present embodiment as described above, the plate 21 is disposed on the optical fiber 5 so that the portion to which the optical circuit 3 is fixed becomes a flat surface. Is suppressed.
[Fourth Embodiment]
Fig.4 (a) is sectional drawing which shows the optical branching element concerning the 4th Embodiment of this invention, FIG.4 (b) is the IV-IV arrow line view of Fig.4 (a). The optical branching element 30 according to the present embodiment is different from the above-described optical branching elements 1, 10, and 20 in the fixing portion between the optical circuit 2 and the optical circuit 3.

In the optical branching element 30, the clad part 5b of the optical fiber 5 and a part of the resin 9 are removed by polishing, grinding or the like. Then, the end face S ₂ of the optical circuit 3 is fixed to the removed portion. As a result, the distance between the optical fiber 5 and the end face S ₂ of the optical circuit 3 becomes shorter, so that the light reflected by the reflection filter 6 can be introduced into the optical fiber 8 more efficiently.
[Fifth Embodiment]
Fig.5 (a) is sectional drawing which shows the optical branching element based on the 5th Embodiment of this invention, FIG.5 (b) is a VV arrow directional view of Fig.5 (a). In the optical branching device 40 according to the present embodiment, the optical circuit 2 of the optical branching device of the above embodiment is a planar optical waveguide type optical circuit 41. That is, the optical branching element 40 includes a planar optical waveguide type optical circuit 41 and the optical circuit 3 that is obliquely fixed to the upper surface of the optical circuit 41.

  The optical circuit 41 includes a substrate 42 made of quartz, pyrex, silicon or the like, and a planar optical waveguide portion 43 formed on the substrate 42. The planar optical waveguide portion 43 includes a clad portion 43a and a plurality of core portions 43b that are formed in the clad portion 43a in parallel and at equal intervals.

The planar optical waveguide portion 43 has an end face S ₃ which is inclined at a predetermined inclination angle alpha (degrees) with respect to the vertical axis L ₂ perpendicular to the optical axis L ₁ of the core portion 43b. A reflection filter 6 is provided on the surface of the end face S _{3 in} the same manner as the optical branching element 1. The reflection filter 6 in this case may also be attached to the surface of the end face S ₁ of the optical circuit 2 with an adhesive such as resin, or may be formed by vapor deposition.

The end surface S ₂ of the optical circuit 3 is fixed to the upper surface of the cladding portion 43 a of the planar optical waveguide portion 43, and a part of the signal light transmitted through the core portion 43 b is branched by being reflected by the reflection filter 6. The light is incident on each optical fiber 8 of the optical circuit 3. Note that the planar optical waveguide portion 43 and the optical circuit 3 are bonded by, for example, the resin 9 (not shown) described above.

  In such an optical branching element 40, the end face of the optical fiber 8 of the optical circuit 3 is fixed to the upper surface part of the planar optical waveguide part 43, so that the branched light is the same as the optical branching element of the above-described embodiment. Can be prevented from entering the adjacent optical fiber. Moreover, since the optical fiber 8 of the optical circuit 3 can be connected perpendicularly to the incident surface of an optical element such as a photodetector, the polarization dependency of the optical element can be reduced. Furthermore, since it is possible to configure using a thinner substrate than in the case of an optical fiber, a downsized optical branching element can be realized.

6A is a cross-sectional view showing a modification of the optical branching element 40 shown in FIG. 5, and FIG. 6B is a view taken along the line VI-VI in FIG. 6A. As shown in FIG. 6, the optical branching element 40 may not include the substrate 42 of the optical circuit 41. Thereby, the optical branching element 40 can be further downsized.
[Sixth Embodiment]
Fig.7 (a) is sectional drawing which shows the optical branching element based on the 6th Embodiment of this invention, FIG.7 (b) is a VII-VII line arrow directional view of Fig.7 (a). In the optical branching device 50 according to the present embodiment, the optical circuit 3 of the optical branching device 40 shown in FIG. 6 is a planar optical waveguide type optical circuit 51.

  The optical circuit 51 has the same structure as that of the optical circuit 41, and includes a substrate 52 formed of quartz, pyrex, silicon, or the like, and a planar optical waveguide portion 53 formed on the substrate 52. Yes. The planar optical waveguide portion 53 includes a clad portion 53a and a plurality of core portions 53b that are formed in the clad portion 53a in parallel and at equal intervals.

  Since such an optical branching element 50 is configured by using a planar optical waveguide type optical circuit that can use a thinner substrate as compared with the case of an optical fiber, a miniaturized optical branching element can be used. Can be realized.

Fig.8 (a) is sectional drawing which shows the modification of the optical branching element 50 shown in FIG. 7, FIG.8 (b) is a VIII-VIII line arrow directional view of Fig.8 (a). As shown in FIG. 8, the optical branching element 50 may not include the substrates 42 and 52 of the optical circuits 41 and 51. Thereby, the optical branching element 50 can be further downsized.
[Seventh Embodiment]
Fig.9 (a) is sectional drawing which shows the optical branching element based on the 7th Embodiment of this invention, FIG.9 (b) is a IX-IX arrow directional view of Fig.9 (a). The optical branching device 60 according to the present embodiment includes an optical circuit 61 and an optical circuit 3 that is obliquely fixed to the upper surface portion of the optical circuit 61. The optical circuit 61 includes a partition wall 62 between adjacent optical fibers 5 in the optical circuit 2 of the optical branching element 1 shown in FIG. According to such an optical branching element 60, even if the light reflected by the reflection filter 6 is diffused, the diffused light is blocked by the partition wall, so that the light reflected by the reflection filter 6 is reflected by the optical circuit 3. It enters only the corresponding optical fiber 8. Therefore, it is possible to prevent the light reflected by the reflection filter 6 from entering the adjacent optical fiber 8 that should not be incident.

FIG. 10 is a diagram illustrating a process of forming the partition wall 62. In FIG. 10A, first, an array substrate 4 on which a plurality (eight in the figure) of optical fibers 5 are arrayed and fixed is prepared. The arrangement pitch P of the optical fibers 5 at this time is, for example, about 127 μm. Then, one side of the surface S a plurality of V-shaped grooves 63 to ₄ prepared positioning substrate 62a which is formed, on the optical fiber 5 and positioning the substrate 62a so that the optical fiber 5 is engaged with the V-groove 63 Placed on. As a result, the optical fiber 5 is positioned on the array substrate 4 with high accuracy. Note that the depth D of the V-shaped groove 63 is, for example, about 105 μm. Note that the positioning substrate 62a is preferably formed of silicon having good cutting properties.

Next, refer to FIG. 10A, after positioning substrate 62a is placed on optical fiber 5, resin 64 is filled between positioning substrate 62a and array substrate 4. In FIG. Then, the positioning substrate 62 a is fixed to the array substrate 4 and the optical fiber 5 by solidifying the resin 64. Next, the surface S ₅ side of the positioning substrate 62a opposite to the surface S ₄ is polished by the polishing machine 65, and the side surface of the optical fiber 5 is exposed. Thereby, the optical circuit 61 provided with the partition 62 between the adjacent optical fibers 5 can be obtained (refer FIG.10 (C)). At this time, the partition wall 62 located between the adjacent optical fibers has a triangular shape. The resin 64 is preferably made of a material having a high Young's modulus filled with a filler of quartz or mica in order to prevent the optical fiber 5 from moving due to resistance when being polished by the polishing machine 65.

Fig.11 (a) is sectional drawing which shows the modification of the optical branching element 60 which concerns on this embodiment, FIG.11 (b) is an XX arrow directional view of Fig.11 (a). Optical branch element 60 shown in FIG. 11, the cladding portion 5b of the optical fiber 5 are partially removed in the fixing sites of the optical circuit 3, the end face S ₁ of the core portion 5a and the optical circuit 3 of the optical fiber 5 The distance is shorter than the radius R of the optical fiber 5. Thereby, since the distance between the optical fiber 5 of the optical circuit 61 and the optical fiber 8 of the optical circuit 3 is shortened, the light reflected by the reflection filter 6 can be efficiently introduced into the optical fiber 8.

When such an optical circuit 61 is formed, it is performed in the same manner as the method of forming the partition wall 62 shown in FIG. 10, and as shown in FIG. 12A, the surface S ₅ of the positioning substrate 62a is connected to the cladding portion 5b. Remove up to a part. Thereby, a part of the clad of the optical fiber 5 is removed, and the optical circuit 61 including the partition wall 62 between the adjacent optical fibers 5 can be obtained (see FIG. 12B).
[Eighth Embodiment]
FIG. 13A is a cross-sectional view showing an optical branching element unit according to the eighth embodiment of the present invention, and FIG. 13B is a view taken along line XI-XI in FIG. . The optical branching element unit 70 includes two optical branching elements 1 according to the first embodiment. The two optical branching elements 1 are joined and integrated at the lower surfaces of the optical circuits 2, that is, at the surfaces opposite to the surface of the optical circuit 2 where the optical circuit 3 is fixed. .

  In such an optical branching element unit 70, the number of signal light branches is doubled compared to the optical branching element 1. For this reason, it is effective when there is no space in the arrangement direction of the optical fibers 5.

In addition, although the optical branching element unit 70 of this embodiment is comprised using the optical branching element 1 which concerns on the said 1st Embodiment, the optical branching element 10 which concerns on the said 2nd-7th embodiment, 20, 30, 40, 50, 60 may be used.
[Ninth Embodiment]
FIG. 14 is a diagram showing an embodiment of an optical branch device according to the ninth embodiment of the present invention, and FIG. 15 is a block diagram thereof. 14 and 15 show a state in which an optical fiber array 81 as an example of an optical element is applied to the optical branching device 80 according to the present embodiment.

  In the optical branch element device 80, the end 82 on one side of the optical fiber 8 of the optical circuit 3 in the optical branch element 1 is connected perpendicularly to the incident surface 84 of the photodiode 83. The same number of photodiodes 83 as the optical fibers 8 are provided and correspond to each optical fiber 8. The optical fiber 8 is configured to transmit branched light that is branched when the signal light transmitted through the optical fiber 5 is reflected by the reflection filter 6. The branched light is transmitted through the optical fiber 8 and is incident on the photodiode 83. Note that, since the photodiodes 83 are arranged in the arrangement direction of the optical fibers 8 (direction perpendicular to the paper surface of FIG. 14), one photodiode 83 is shown in FIG.

  In the present embodiment, an optical fiber array 81 in which a plurality of optical fibers 86 are arranged on a substrate 85 is fixed to the surface of the reflection filter 6 of the optical branch element device 80 opposite to the optical circuit 2. . The optical fiber 86 of the optical fiber array 81 is provided corresponding to each optical fiber 5 of the optical circuit 2, and transmitted light that has passed through the reflection filter 6 is transmitted.

  According to the optical branch element device 80 according to the present embodiment, the optical fiber 8 of the optical circuit 3 fixed to the optical circuit 2 is connected perpendicularly to the incident surface 84 of the photodiode 83. Therefore, since the branched light transmitted through the optical fiber 8 can be made to enter the incident surface 84 of the photodiode 83 perpendicularly, the polarization dependency of the photodiode 83 is reduced, and the light receiving sensitivity can be improved.

In addition, although the optical branch element device 80 of this embodiment is comprised using the optical branch element 1 which concerns on the said 1st Embodiment, the optical branch element 10 which concerns on the said 2nd-7th embodiment, You may comprise using 20, 30, 40, 50, 60.
[Tenth embodiment]
FIG. 16 is a diagram showing an optical branching device including an optical branching element according to the tenth embodiment of the present invention, and FIG. 17 is a block diagram thereof. In FIG. 16, the optical branching device 90 includes an optical branching unit 91 and an optical circuit 92. The optical branching unit 91 has the same structure as the optical branching element 1 according to the first embodiment, but the number of optical fibers 5 is twice that of the optical fibers 8 as shown in FIG. The difference is that the reflection filter 6 is not provided on the end face S ₁ of the optical circuit 2.

  The optical circuit 92 is a planar optical waveguide type optical circuit, and includes a substrate 93 formed of quartz, pyrex, silicon, or the like, and a planar optical waveguide portion 94 formed on the substrate 93. . The planar optical waveguide portion 94 includes a clad portion 94a and a plurality of core portions 94b that are formed in the clad portion 94a in parallel and at equal intervals.

A reflection filter 6 is provided on one end face S ₆ of the optical circuit 92. The reflection filter 6 is formed, for example, by vapor deposition on the end surface S _6. By using vapor deposition, it is possible to easily form a large number of reflection filters. In addition, since the reflection filter 6 is formed on the side of the optical circuit 92 that is smaller than the optical circuit 2 and has a simple structure, the influence of optical fiber routing and the like is reduced, so the reflection filter 6 is formed with better workability. be able to. Of course, the reflection filter 6 may be attached to the end surface S ₁ of the optical circuit 2 with an adhesive such as resin. Such an optical circuit 92 is fixed to the optical circuit 2 by the reflection filter 6 being bonded to the end surface S ₁ of the optical circuit 2.

FIG. 18 is an enlarged view showing a region Z of FIG. 16, and is a view showing a fixing portion between the optical circuit 2 and the optical circuit 92. As shown in FIG. As shown in FIG. 18, the reflection filter 6 of the optical circuit 92 and the end surface S ₁ of the optical circuit 2 are bonded to each other with an adhesive 95 such as a resin that matches the refractive index. The light branching section 91 may have a configuration in which the reflection filter 6 is provided on the optical circuit 2 side, that is, the same structure as the light branching element 1. In that case, the layer of the adhesive 95 is formed between the reflection filter 6 and the end face S ₆ of the optical circuit 92.

The optical branch device 96 of this embodiment includes the optical branch element 90 and the photodiode 83 as described above. A variable optical attenuator 97 formed using a micro electro mechanical system (MEMS) technique is connected to the end face S ₇ of the optical circuit 92. The variable optical attenuator 97 has a substrate 98, and a planar optical waveguide portion 99 is formed on the substrate 98.

  As shown in FIG. 17, the planar optical waveguide portion 99 of the variable optical attenuator 97 has an optical path M and an optical path N through which the transmitted light transmitted through the reflection filter 6 passes. Further, the planar optical waveguide portion 99 is provided with a mirror 100 that reflects light passing on the optical path M toward the optical path N. Such a variable optical attenuator 97 adjusts the intensity of reflected light by driving the mirror 100 while being controlled by the control unit 101.

According to the optical branching device 96 according to the present embodiment as described above, even if the end face of the element such as the variable optical attenuator is at an inclination angle that does not coincide with the end face S ₁ of the optical circuit 2, it conforms to the inclination angle. By using the optical circuit 92 having the end face S ₇ to be applied, it can be applied.

The optical circuit 92 may be one in which optical fibers are arranged. Further, in the optical branching element device 96 of the present embodiment, the fixed portion between the optical circuit 2 and the optical circuit 3 is the optical branching element 10, 20, 30, 40, 50, according to the second to seventh embodiments. A structure such as 60 may be used.
[Eleventh embodiment]
FIG. 19 is a schematic diagram illustrating an example of a wavelength division multiplexing optical transmission system including the above-described optical branching element. The wavelength division multiplexing optical transmission system according to the present embodiment is merely an example of an optical communication system to which the optical branching element according to the present invention is applied, and the optical branching element according to the present invention is a variety of other optical communication systems. It is applicable to.

  In FIG. 19, the wavelength division multiplexing optical transmission system 110 includes optical branching elements 112 and 113 having a plurality of optical waveguides 111 and an optical variable attenuator array 115 having a plurality of optical variable attenuators 114. The optical variable attenuator array 115 is disposed between the optical branching element 112 and the optical branching element 113, and each optical waveguide 111 and each optical variable attenuator 114 of the optical branching elements 112, 113 includes the optical waveguide 116. Are connected to each other.

  Each optical waveguide 111 of the optical branching element 112 is connected to the light source 118 through the optical waveguide 117. On the other hand, each optical waveguide 111 of the optical branching element 113 is connected to an arrayed waveguide grating (AWG) 120 via the optical waveguide 119. The arrayed waveguide grating 120 multiplexes the optical signals of the respective wavelengths and guides them to one optical waveguide 121. An optical amplifier 122 is connected to the optical waveguide 121.

  A part of the light transmitted through each optical waveguide 111 of the optical branching elements 112 and 113 is branched by the reflection filter 6 and transmitted through the optical waveguide 123. An optical monitor 124 that detects the power of light from the light source 118 is connected to the optical waveguide 123 of the optical branching element 112. An optical monitor 125 that detects the power of the light attenuated by the optical variable attenuator 121 is connected to the optical waveguide 123 of the optical branching element 113.

  The optical branching elements 112 and 113 and the optical variable attenuator array 115 are connected to the controller 126. The controller 126 includes a voltage source that supplies a voltage to each optical variable attenuator 114 and a supply voltage control unit. Based on the detection values of the optical monitors 124 and 125, the controller 126 controls the voltage signal sent to each optical variable attenuator 114 so that the output light amount becomes a desired value.

  As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the optical branching device has a plurality of optical waveguides (core portion or optical fiber of the planar optical waveguide portion), but may be one.

Fig.1 (a) is sectional drawing which shows the optical branching element concerning the 1st Embodiment of this invention, FIG.1 (b) is the II arrow directional view of Fig.1 (a). FIG. 2A is a cross-sectional view showing an optical branching element according to the second embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line II-II in FIG. Fig.3 (a) is sectional drawing which shows the optical branching element which concerns on the 3rd Embodiment of this invention, FIG.3 (b) is the III-III arrow directional view of Fig.3 (a). Fig.4 (a) is sectional drawing which shows the optical branching element concerning the 4th Embodiment of this invention, FIG.4 (b) is the IV-IV arrow line view of Fig.4 (a). Fig.5 (a) is sectional drawing which shows the optical branching element based on the 5th Embodiment of this invention, FIG.5 (b) is a VV arrow directional view of Fig.5 (a). 6A is a cross-sectional view showing a modification of the optical branching element 40 shown in FIG. 5, and FIG. 6B is a view taken along line VI-VI in FIG. 6A. Fig.7 (a) is sectional drawing which shows the optical branching element based on the 6th Embodiment of this invention, FIG.7 (b) is a VII-VII line arrow directional view of Fig.7 (a). Fig.8 (a) is sectional drawing which shows the modification of the optical branching element 50 shown in FIG. 7, FIG.8 (b) is a VIII-VIII line arrow directional view of Fig.8 (a). Fig.9 (a) is sectional drawing which shows the optical branching element based on the 7th Embodiment of this invention, FIG.9 (b) is a IX-IX arrow directional view of Fig.9 (a). It is a figure which shows the formation process of the partition 62 shown in FIG. Fig.11 (a) is sectional drawing which shows the modification of the optical branching element 60 which concerns on this embodiment, FIG.11 (b) is an XX arrow directional view of Fig.11 (a). It is a figure which shows the formation process of the partition 62 shown in FIG. FIG. 13A is a cross-sectional view showing an optical branching element unit according to the eighth embodiment of the present invention, and FIG. 13B is a view taken along line XI-XI in FIG. . It is a figure which shows one form of the optical branching element device which concerns on the 9th Embodiment of this invention. FIG. 15 is a block diagram of FIG. 14. It is a figure which shows the optical branching device provided with the optical branching element which concerns on the 10th Embodiment of this invention. FIG. 17 is a block diagram of FIG. 16. It is an enlarged view which shows the area | region Z of FIG. It is a schematic diagram which shows an example of the wavelength division multiplexing transmission system provided with the optical branching element which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical branching element, 2, 3 ... Optical circuit, 4 ... Array substrate, 5 ... Optical fiber, 5a ... Core part, 5b ... Cladding part, 6 ... Reflection filter, 7 ... Array substrate, 8 ... Optical fiber, 8a ... Core part, 9 ... Resin, 10 ... Optical branching element, 20 ... Optical branching element, 21 ... Plate, 30 ... Optical branching element, 40 ... Optical branching element, 41 ... Optical circuit, 41, 51 ... Optical circuit, 42 ... Substrate 43 ... Planar optical waveguide part, 43a ... Cladding part, 43b ... Core part, 50 ... Optical branching element, 51 ... Optical circuit, 52 ... Substrate, 53 ... Planar optical waveguide part, 53a ... Cladding part, 53b ... Core part, DESCRIPTION OF SYMBOLS 60 ... Optical branching element, 61 ... Optical circuit, 62a ... Positioning board | substrate 62a, 62 ... Partition, 63 ... V-shaped groove, 64 ... Resin, 70 ... Optical branching element unit, 80 ... Optical branching element device, 81 ... Optical fiber Array, 82 ... end, 83 ... photodiode ( 84 ... incident surface, 85 ... substrate, 86 ... optical fiber, 90 ... optical branching element, 91 ... light branching part, 92 ... optical circuit, 93 ... substrate, 94 ... planar optical waveguide part, 94a ... cladding part 94b ... Core part, 95 ... Adhesive, 96 ... Optical branching device, 96 ... Optical branching element device, 97 ... Variable optical attenuator, 98 ... Substrate, 99 ... Planar optical waveguide part, 110 ... Wavelength division multiplexing optical transmission system, 112,113 ... optical branch element, 114 ... optical variable attenuator, 115 ... optical variable attenuator array 125 ... optical monitor, L ₁ ... optical axis, L ₂ ... vertical axis, R ... radius, S _1, S _2, S ₃ ... end face, S ₄ ... first face, S ₅ ... second face, S ₆ , S ₇ ... end face, α ... inclination angle, β ... end face angle.

Claims (16)

A first optical circuit including a first optical waveguide having an end face inclined with respect to a vertical axis orthogonal to the optical axis;
A reflection filter that reflects a part of the signal light transmitted through the first optical waveguide with a predetermined reflectance;
A second optical circuit configured to include a second optical waveguide that is obliquely fixed to the first optical circuit and that transmits the light branched when the signal light is reflected by the reflection filter. An optical branching device characterized. 2. The optical branching element according to claim 1, wherein at least one of the first optical circuit and the second optical circuit is a planar optical waveguide type optical circuit. 2. The optical branching element according to claim 1, wherein at least one of the first optical waveguide and the second optical waveguide is an optical fiber. 4. The optical branching element according to claim 3, wherein the second optical circuit is fixed to a side surface of the first optical circuit through a resin. The first optical circuit has an optical fiber fixed to an array substrate, and is optically transparent disposed on the opposite side of the array member with respect to the optical fiber so as to face the array substrate. The optical branching element according to claim 1, further comprising a plate, wherein the optical fiber and the second optical circuit are fixed via the plate. The first optical circuit is an optical fiber fixed to an array substrate, the second optical circuit is fixed to the cladding of the optical fiber, and the second optical circuit of the cladding is fixed to the part. 2. The optical branching element according to claim 1, wherein a distance between the core of the optical fiber and the second optical circuit is shorter than a radius of the optical fiber. The first optical circuit includes N (N is a plurality) first optical waveguides, and the second optical circuit includes N second optical waveguides corresponding to the N first optical waveguides, respectively. The first optical circuit has an optical fiber fixed to an array substrate, and at least one of the adjacent optical fibers is provided with a partition wall. The light branching element according to claim 1. The second optical circuit is fixed to the cladding of the optical fiber, and the portion of the cladding where the second optical circuit is fixed is such that the distance between the core of the optical fiber and the second optical circuit is that of the optical fiber. 8. The optical branching element according to claim 7, wherein the optical branching element is formed to be shorter than the radius. The partition wall includes a positioning substrate having a groove formed on a first surface, and the groove is engaged with the optical fiber fixed to the array substrate. 8. The optical fiber is formed by removing from a second surface located on the opposite side of the first surface so that a distance to the two optical circuits is equal to or less than a radius of the optical fiber. 9. The optical branching element according to 8. A third optical waveguide is disposed on the opposite side of the first optical circuit with respect to the reflection filter, and includes a third optical waveguide that transmits the signal light transmitted through the reflection optical filter and transmitted through the reflection filter. The optical branching device according to any one of claims 1 to 9, further comprising an optical circuit. 11. The optical branching element according to claim 10, wherein the third optical circuit is a planar optical waveguide type optical circuit. The optical branching device according to claim 10, wherein the third optical waveguide is an optical fiber. The reflection filter is provided on an end face of the third optical waveguide, and the first optical circuit and the third optical circuit are fixed via the reflection filter. 12. The optical branching element according to any one of 12 above. 10. The two optical branching elements according to claim 1, wherein the two optical branching elements are bonded to each other at positions opposite to the second optical circuit with respect to the first optical circuit. An optical branching element unit characterized by being integrated. A first optical circuit including a first optical waveguide having an end face inclined with respect to a vertical axis orthogonal to the optical axis;
A reflection filter that reflects a part of the signal light transmitted through the first optical waveguide with a predetermined reflectance;
A second optical circuit configured to include a second optical waveguide through which light branched by reflecting the signal light by the reflection filter is transmitted;
An optical branching device comprising: an optical element connected to the second optical circuit and receiving the branched light transmitted through the second optical waveguide. A wavelength division multiplexing optical transmission system that performs optical transmission by multiplexing multi-wavelength signal light,
A wavelength division multiplexing optical transmission system comprising the optical branching element according to any one of claims 1 to 9.

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