JP2014157181A - Planar optical waveguide, optical receiver device, and alignment method for planar optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar optical waveguide whose input waveguide and output waveguide are formed at different ends of a base plate and that can be aligned without needing a space for the alignment at an emitting side end of the waveguide, an optical receiver device, and an alignment method for the planar optical waveguide.SOLUTION: A planar optical waveguide 10 comprises input ports 31 and 32 arranged on one end face of a base plate 20, an output port 40 arranged on the other end face of the base plate 20, couplers 51 and 52 formed over the base plate, a processor 60 that processes one of input light beams outputted from the couplers 51 and 52 and outputs the processed input light beam as an output light beam, and a spatial propagation unit 70 that propagates the input light beam outputted from the one of the couplers to the other coupler.

Description

  The present invention relates to a planar optical waveguide, an optical receiver, and a method for aligning the planar optical waveguide, and in particular, a planar optical waveguide in which an input waveguide and an output waveguide are formed at different ends of a substrate, an optical receiver, and the optical waveguide, respectively. The present invention relates to a method for aligning a planar optical waveguide.

  There is a planar lightwave circuit (PLC) in which various optical circuits such as an optical branch circuit are integrated on a substrate. This planar optical waveguide alignment method is disclosed in, for example, Patent Documents 1 and 2. In Patent Document 1, an aligning dummy waveguide is formed in the optical waveguide, and the fiber array is moved by a predetermined distance after aligning the fiber array with respect to the dummy waveguide. A technique for coarsely aligning is disclosed. Further, in Patent Document 2, an input waveguide and an output waveguide are formed on the same end face side of a flat substrate, and an optical signal for alignment is input / output from the same fiber array to adjust the optical waveguide and the fiber array. A technique to keep in mind is disclosed.

  On the other hand, a polarization beam splitter (PBS) or 90 is used as an optical waveguide used in a polarization multiplexing coherent transmission system that performs digital signal processing, which is regarded as a promising means for realizing a next generation transmission system. There is a planar optical waveguide in which hybrid mixers and the like are integrated on the same substrate.

  In this planar optical waveguide for digital coherent transmission, an optical signal and local light are incident from the incident side end of the substrate, and interference light interfered in an orthogonal state by the PBS and the 90-degree hybrid mixer is different from the incident side end. The light is emitted from the emission side end. The interference wave emitted from the planar optical waveguide is further processed in various optical components arranged on the emission side end side of the planar optical waveguide. Here, it is desirable that alignment of the planar optical waveguide can be performed in a state where optical parts such as an amplifier, a light receiving element, and a transimpedance amplifier are mounted on the output side end of the planar optical waveguide.

JP-A-1-283507 JP 2000-206351 A

  When alignment is performed with various optical components mounted on the output side end of a planar optical waveguide, it is difficult to secure a space for arranging an alignment member such as a fiber array or optical power meter at the output side end. It is. In addition, since various optical components must be mounted on the output side end of the planar optical waveguide, the input waveguide and the output waveguide cannot be formed on the same end surface side of the planar substrate.

  An object of the present invention has been made in view of the above-described problems. In a planar optical waveguide in which an input waveguide and an output waveguide are formed at different ends of a substrate, respectively, an exit side end of the planar optical waveguide is provided. An object of the present invention is to provide a planar optical waveguide, an optical receiver, and an alignment method for the planar optical waveguide, which can align the planar optical waveguide without providing an alignment space.

  In order to achieve the above object, a planar optical waveguide according to the present invention is located on a substrate, one end surface of the substrate, the first input port and the second input port on which input light is incident, and the other end surface of the substrate. An output port that emits output light; a first coupler and a second coupler that are formed on the substrate and that divides the input light that has been input from the first input port and the second input port, respectively; A processing unit configured to process one input light output from the first coupler and the second coupler and output it as output light; and another input light formed on the substrate and output from the first coupler. A spatial propagation unit that propagates to the second coupler side and propagates the other input light output from the second coupler to the first coupler side.

  In order to achieve the above object, an optical receiver according to the present invention includes a first optical fiber that makes signal light enter the first input port as input light, and a second optical fiber that makes local light enter the second input port as input light. An optical fiber, the above planar optical waveguide, and a light receiving element that is disposed on the other end surface side of the substrate of the planar optical waveguide and receives output light output from the processing unit.

  In order to achieve the above object, a planar optical waveguide alignment method according to the present invention includes forming a first input port and a second input port on one end surface of a substrate, a processing unit, and a spatial propagation unit on the upper surface of the substrate. And a first coupler that connects the first input port, the processing unit, and the space propagation unit, and a second coupler that connects the second input port, the processing unit, and the space propagation unit, and forms a first optical fiber. And the second optical fiber are opposed to the first input port and the second input port, respectively, and aligning light is incident on the second input port from the second optical fiber, and the first light is transmitted through the space propagation unit. The light intensity of the alignment light emitted from the fiber is measured, and the first optical fiber and the second optical fiber are positioned at a position where the measured light intensity becomes maximum.

  A planar optical waveguide, an optical receiver, and an alignment method for the planar optical waveguide according to the present invention include: a planar optical waveguide in which an input waveguide and an output waveguide are formed at different ends of a substrate; The planar optical waveguide can be aligned without providing a space for alignment at the side end.

1 is a top view of a planar optical waveguide 10 according to a first embodiment of the present invention. It is a block diagram of the optical receiver 90B which concerns on the 1st Embodiment of this invention. It is a top view of PLC100 which concerns on the 2nd Embodiment of this invention. It is a top view of PLC100B which concerns on the 3rd Embodiment of this invention. It is a top view of another PLC100C which concerns on the 3rd Embodiment of this invention.

(First embodiment)
A planar optical waveguide according to the first embodiment of the present invention will be described. A top view of the planar optical waveguide according to the present embodiment is shown in FIG. In FIG. 1, the planar optical waveguide 10 according to the present embodiment includes a substrate 20, a first input port 31, a second input port 32, an output port 40, a first coupler 51, a second coupler 52, a processing unit 60, and spatial propagation. The unit 70 is provided.

  As shown by a dotted line in FIG. 1, optical fibers 81 and 82 for allowing input light to enter the planar optical waveguide 10 are disposed to face the input ports 31 and 32 of the planar optical waveguide 10. In addition, an optical component 83 such as a light receiving element that receives output light emitted from the planar optical waveguide 10 is disposed to face the output port 40 of the planar optical waveguide 10.

  The substrate 20 is a plate-like member formed of quartz or the like. The first input port 31 and the second input port 32 are disposed on the end surface 21, and the output port 40 is disposed on the end surface 22 different from the end surface 21. . A first coupler 51, a second coupler 52, a processing unit 60, and a spatial propagation unit 70 are formed on the upper surface of the substrate 20.

  Input light enters the first input port 31 and the second input port 32 from the optical fibers 81 and 82. The optical signal input from the first input port 31 is output to the processing unit 60 via the first coupler 51 and a part thereof is output to the spatial propagation unit 70. Similarly, the optical signal input from the second input port 32 is output to the processing unit 60 via the second coupler 52 and a part thereof is output to the spatial propagation unit 70.

  The processing unit 60 performs predetermined processing on the input light that is input and outputs the input light to the output port 40 as output light. For example, the processing unit 60 combines the optical signal input from the optical fiber 81 and the optical signal input from the optical fiber 82 and outputs the resultant as output light. The output light emitted from the output port 40 is detected by an optical component 83 such as a light receiving element, and a signal included in the output light is extracted.

  The space propagation unit 70 is a recess formed on the upper surface of the substrate 20, and an optical waveguide connected to the first coupler 51 and a light beam connected to the second coupler 52 are formed on opposite side walls of the space propagation unit 70. The waveguide is exposed. In the present embodiment, the width of the space propagation unit 70 is designed to be about 50 μm so that the distance between the two optical waveguides is about 50 μm. Accordingly, the input light guided from the first coupler 51 to the spatial propagation unit 70 propagates through the spatial propagation unit 70 and is guided to the second coupler 52, and the input light guided from the second coupler 52 to the spatial propagation unit 70. Propagates through the space propagation unit 70 and is guided to the first coupler 51.

  In addition, it is desirable to fill the space propagation unit 70 with a light shielding member that shields input light after the planar optical waveguide 10 is aligned. By filling the space propagation unit 70 with a light blocking member, the input light guided from one coupler into the space propagation unit 70 propagates through the space propagation unit 70 and is input to the other coupler as stray light. Can be avoided. Here, the light shielding member may be any member that absorbs an optical signal in a wavelength band including the wavelength of the optical signal propagating in the planar optical waveguide 10, and a light absorbing gel, a light shielding plate, or the like can be applied.

  Next, the alignment procedure between the planar optical waveguide 10 and the optical fibers 81 and 82 according to this embodiment will be described. When aligning the planar optical waveguide 10 and the optical fibers 81 and 82, first, visible light from the end surface of the optical fibers 81 and 82 opposite to the input ports 31 and 32 side (hereinafter referred to as the opposite end surface). , And the optical fibers 81 and 82 are moved so that the centers of visible light emitted from the optical fibers 81 and 82 substantially coincide with the centers of the input ports 31 and 32 (coarse alignment).

  Next, an optical signal for alignment is incident from the opposite end face of the optical fiber 82 that has been roughly aligned. The alignment optical signal emitted from the optical fiber 82 is input to the second coupler 52 via the second input port 32, and most of the optical signal is propagated to the processing unit 60, while a part thereof is a spatial propagation unit. Propagated to the first coupler 51 via 70. The alignment optical signal propagated from the optical fiber 82 to the first coupler 51 is emitted from the first input port 31 toward the optical fiber 81.

  Then, the optical intensity of the optical signal for alignment input to the optical fiber 81 is measured by an optical power meter disposed on the opposite end face of the optical fiber 81, and the optical fiber is positioned at the position where the measured value of the optical intensity becomes the maximum value. 81 is moved and fixed at that position (fine alignment of the optical fiber 81). After the optical fiber 81 is precisely aligned, the optical fiber 82 is moved to a position where the measured value of the light intensity of the alignment optical signal input to the optical fiber 81 is the maximum value, and fixed at that position. (Precise alignment of the optical fiber 82). In addition, it is desirable to fill the space propagation unit 70 with a light shielding member after the fine alignment between the planar optical waveguide 10 and the optical fibers 81 and 82 is completed.

  As described above, the planar optical waveguide 10 according to this embodiment includes the couplers 51 and 52 that guide part of the input light input from the input ports 31 and 32 to the spatial propagation unit 70 on the upper surface of the substrate 20. A spatial propagation unit 70 for guiding the input light guided from the coupler to the other coupler is formed. Therefore, by inputting the alignment optical signal from one optical fiber and measuring the optical intensity of the alignment optical signal emitted from the other optical fiber, the planar optical signal is obtained based on the measured value of the optical intensity. The waveguide 10 and the optical fibers 81 and 82 can be aligned with high accuracy. This alignment operation can be performed only on the end side where the input ports 31 and 32 are disposed, and can be performed with the optical component 83 such as a light receiving element disposed on the end side where the output port 40 is disposed. it can.

  Therefore, in the planar optical waveguide 10 in which the input ports 31 and 32 and the output port 40 are respectively arranged on the different end portions 21 and 22 of the substrate 20, the optical component 83 such as a light receiving element is provided on the end face 22 side where the output port 40 is arranged. Alignment between the planar optical waveguide 10 and the optical fibers 81 and 82 can be performed in a state in which is placed.

  The above-described planar optical waveguide 10 can be disposed in various optical transceivers. As an example, FIG. 2 shows a configuration diagram when the planar optical waveguide according to the present embodiment is arranged in an optical receiver used in digital coherent transmission. The optical receiver 90B of FIG. 2 includes a first optical fiber 81B that makes signal light incident on the first input port 31B, a second optical fiber 82B that makes local light incident on the second input port 32B, the planar optical waveguide 10B, An optical component 83B is provided. In FIG. 2, optical fibers 81B and 82B are arranged to face input ports 31B and 32B of the planar optical waveguide 10B, and one optical component 83B is arranged to face each of four pairs of output ports. In the present embodiment, a light receiving element is applied as the optical component 83B.

  The planar optical waveguide 10B according to this embodiment includes eight output ports 41B-48B, and separates input light input from the input ports 31B and 32B into two orthogonal polarization components in the processing unit 60B. Interference occurs and the light is emitted from the eight output ports 41B-48B.

  The optical receiving device 90B configured as described above operates as follows when receiving an optical signal from an optical transmission device (not shown). That is, the optical fiber 81B enters the optical signal received from the optical transmission device into the first input port 31B, and the second optical fiber 82B enters the local light input from the oscillator (not shown) into the second input port 32B.

  The optical signal received from the optical transmission device and the local light input from the oscillator are separated into two orthogonal polarization components in the planar optical waveguide 10B, interfere with each other, and are output from the output ports 41B-48B. The interference light emitted from the output ports 41B-48B is received by the four light receiving elements 83B and various information is read.

  Further, when aligning the planar optical waveguide 10B and the optical fibers 81B and 82B in the optical receiving device 90B, an optical signal for alignment is incident from the optical fiber 82B, and the second input port 32B and the second input port 32B. The optical intensity of the aligning optical signal emitted from the optical fiber 81B is measured via the coupler 52B, the spatial propagation unit 70B, the first coupler 51B, and the first input port 31B, and the light reaches the position where the measured value becomes maximum. The fibers 81B and 82B are positioned. It is desirable to fill the space propagation part 70B with a light shielding member after alignment.

(Second Embodiment)
A second embodiment will be described. A top view of a planar lightwave circuit (PLC) according to this embodiment is shown in FIG. In FIG. 3, the PLC 100 according to this embodiment includes a substrate 200, two input ports 310 and 320, two output ports 410 and 420, two input optical waveguides 510 and 520, and two output optical waveguides 610 and 620. The optical interference unit 700 and the adjustment route 800 are provided.

  The substrate 200 is a flat plate having an input side end 210 and an output side end 220 different from the input side end 210. Input optical waveguides 510 and 520, output optical waveguides 610 and 620, an optical interference unit 700, and an adjustment route 800 are arranged on the upper surface of the substrate 200.

  The input ports 310 and 320 are located at the input side end portion 210 of the substrate 200, and light signals are incident from the optical fibers 910 and 920 arranged to face each other. Optical signals incident on the input ports 310 and 320 are guided to the input optical waveguides 510 and 520.

  The output ports 410 and 420 are located at the output side end 220 of the substrate 200 and emit the interference light from the light interference unit 700 guided by the output optical waveguides 610 and 620 to the outside.

  The input optical waveguides 510 and 520 guide optical signals incident on the input ports 310 and 320 to the optical interference unit 700. The output optical waveguides 610 and 620 guide the interference light output from the optical interference unit 700 to the output ports 410 and 420.

  The optical interference unit 700 causes the optical signals input from the optical fibers 910 and 920 guided by the input optical waveguides 510 and 520 to interfere with each other, and outputs the interference light to the output optical waveguides 610 and 620.

  As shown in FIG. 3, the adjustment route 800 includes couplers 811 and 812, connection optical waveguides 821 and 822, a spatial propagation unit 830, matching oil 840 and a light absorbing gel 850 (not shown in FIG. 3).

  The couplers 811 and 812 divide the optical signals input from the input ports 310 and 320 to the input optical waveguides 510 and 520, respectively, and output them to the optical interference unit 700 side and the spatial propagation unit 830 side. In this embodiment, the couplers 811 and 812 divide the optical signal into about 9: 1, and output about 9/10 to the optical interference unit 700 side and about 1/10 to the spatial propagation unit 830 side. Further, the couplers 811 and 812 output optical signals input from the space propagation unit 830 side to the input ports 310 and 320 side, respectively.

  The connection optical waveguide 821 connects the coupler 811 and the spatial propagation unit 830. Similarly, the connection optical waveguide 822 connects the coupler 812 and the spatial propagation unit 830. One end surfaces of the connecting optical waveguides 821 and 822 are disposed to face each other in the space propagation portion 830.

  The space propagation part 830 is a recess formed on the substrate 200 and is filled with either the matching oil 840 or the light absorbing gel 850 in this embodiment. When the space propagation part 830 is filled with the matching oil 840, the optical signal emitted from one connection optical waveguide is propagated to the other connection optical waveguide, and when the light absorbing gel 850 is filled Optical signals emitted from the connecting optical waveguides 821 and 822 are absorbed by the light absorbing gel 850 in the space propagation unit 830.

  The matching oil may be a member having a refractive index equivalent to that of the cores of the connecting optical waveguides 821 and 822. The light absorbing gel 850 may be a member that absorbs an optical signal in a wavelength band including the wavelength of the optical signal propagating through the PLC 100.

  In the PLC 100 configured as described above, the space propagation portion 830 of the adjustment route 800 is filled with the light absorbing gel 850 when used. The optical signals incident from the input ports 310 and 320 are partly absorbed by the light absorbing gel 850 in the space propagation unit 830, while most of the light signals are input to the optical interference unit 700, They interfere with each other and are emitted from the output ports 410 and 420 as interference light.

  Next, the alignment procedure between the PLC 100 according to the present embodiment and the optical fibers 910 and 920 will be described. When aligning the optical fibers 910 and 920 in the PLC 100, first, the matching oil 840 is filled in the space propagation unit 830 of the adjustment route 800. In this state, the optical fiber 910 and the input port 310 and the optical fiber 920 and the input port 320 are roughly aligned.

  This rough alignment is performed, for example, by allowing visible light to enter from the opposite end surfaces of the input ports 310 and 320 of the optical fibers 910 and 920 and facing the input ports 310 and 320 of the optical fibers 910 and 920 (hereinafter referred to as alignment). This is implemented by moving the optical fibers 910 and 920 so that the centers of visible light emitted from the side end faces substantially coincide with the centers of the input ports 310 and 320.

  Next, an optical signal for alignment is incident from the opposite end face of the optical fiber 920 that has been roughly aligned. The alignment optical signal incident on the optical fiber 920 propagates through the optical fiber 920 and is emitted from the alignment-side end surface of the optical fiber 920. Since the optical fiber 920 and the input port 320 are roughly aligned, the optical signal for alignment emitted from the alignment side end face of the optical fiber 920 is input to the input optical waveguide 520 via the input port 320. input.

  About 9/10 of the alignment optical signal input to the input optical waveguide 520 is output to the optical interference unit 700 side in the coupler 812, and about 1/10 is output to the connection optical waveguide 822. Since the optical signal for alignment from the input port 320 input to the optical interference unit 700 is not input from the input port 310 side, it is guided to the output optical waveguides 610 and 620 without interfering with the output port. The light is emitted from 410 and 420 to the outside. On the other hand, the alignment optical signal input to the connection optical waveguide 822 is guided to the spatial propagation unit 830. At this time, since the space propagation unit 830 is filled with the matching oil 840, the alignment optical signal is propagated in the space propagation unit 830 to the connection optical waveguide 821 via the matching oil 840 and the coupler 811. The light is emitted from the input port 310 via the input optical waveguide 510.

  The alignment optical signal emitted from the input port 310 is input to the coarsely aligned optical fiber 910, and the light intensity is measured by an optical power meter disposed opposite to the opposite end face of the optical fiber 910. Then, the optical fiber 910 is moved to a position where the measured value of the light intensity is maximized, and fixed at that position, whereby the optical fiber 910 and the input port 310 of the PLC 100 are aligned. After aligning the optical fiber 910, the optical fiber 920 is moved to a position where the light intensity measured by the optical power meter disposed opposite to the opposite end face of the optical fiber 910 is maximized, and fixed at that position, The optical fiber 920 and the input port 320 of the PLC 100 are aligned.

  After the alignment between the optical fibers 910 and 920 and the input ports 310 and 320 of the PLC 100 is completed, the matching oil 840 filled in the space propagation part 830 is removed, and the light absorption gel 850 is filled in the space propagation part 830. To do. By filling the space propagation part 830 with the light absorbing gel 850, the connection between the connecting optical waveguides 821 and 822 is optically cut.

  As described above, the PLC 100 according to the present embodiment has the couplers 811 and 812 that guide a part of the input light input from the input ports 310 and 320 to the spatial propagation unit 830, and one of the couplers on the upper surface of the substrate 200. And a spatial propagation unit 830 for guiding the input light to the other coupler. Therefore, by inputting the optical signal for alignment from one optical fiber and measuring the optical intensity of the optical signal for alignment emitted from the other optical fiber, the PLC 100 and the The optical fibers 910 and 920 can be aligned with high accuracy.

(Third embodiment)
A third embodiment will be described. FIG. 4 shows a top view of the PLC according to the present embodiment. The PLC 100B shown in FIG. 4 is used for digital coherent communication. A signal port 310B and a local port 320B are arranged at the input side end 210B of the quartz-based substrate 200B, and eight output ports 410B-480B are arranged at the output side end 220B. In addition, the input optical waveguides 510B and 520B, the output optical waveguides 610B to 680B, the optical interference unit 700B, and the adjustment route 800B are integrated on the upper surface of the substrate 200B. Here, the optical interference unit 700B mainly includes a polarization beam splitter (PBS) 710B, a power splitter 720B, and two 90-degree hybrid mixers 731B and 732B.

  In the PLC 100B configured as described above, an optical signal used in a digital coherent manner from the optical fiber 910B is input to the signal port 310B, and local light is input from the optical fiber 920B to the local port 320B.

  The optical signal and part of the local light input to the PLC 100B are input to the adjustment route 800B as in the PLC of FIG. 3 described in the second embodiment. However, during digital coherent communication, the spatial propagation unit of the adjustment route 800B Since 830B is filled with the light absorbing gel, the optical signal and local light input to the adjustment route 800B are absorbed by the light absorbing gel. Here, in this embodiment, the optical signal input from the signal port 310B and the local port 320B and about 1/10 of the local light are designed to be input to the adjustment route 800B side. Further, the gap width of the space propagation part 830B was designed to be 50 μm or less.

  On the other hand, the optical signal input to the optical interference unit 700B is separated into two orthogonal polarization components (TE component and TM component) in the PBS 710B and input to the 90-degree hybrid mixers 731B and 732B, respectively. On the other hand, the local light input to the optical interference unit 700B is branched into two at the power splitter 720B in the TM polarization state, and input to the 90-degree hybrid mixers 731B and 732B.

  The TE component and local light of the optical signal input to the 90-degree hybrid mixer 731B interfere with each other and are output from the four output ports 410B-440B. Similarly, the TM component and local light of the optical signal input to the 90-degree hybrid mixer 732B interfere with each other and are output from the four output ports 450B-480B.

  Next, alignment procedures between the PLC 100B according to the present embodiment and the optical fibers 910B and 920B will be described. In this embodiment, when the optical fibers 910B and 920B are aligned with the PLC 100B, nothing is filled in the space propagation unit 830B of the adjustment route 800B. That is, air exists in the space propagation unit 830B. In this state, the optical fiber 910B and the signal port 310B, and the optical fiber 920B and the local port 320B are roughly aligned.

  In this rough alignment, visible light is incident from the opposite end faces of the optical fibers 910B and 920B, and the optical fiber 910B is placed so that the visible light emitted from the optical fibers 910B and 920B is at the center of the signal port 310B and the local port 320B. , 920B. By performing rough alignment, the connection loss between the optical fibers 910B and 920B and the signal port 310B and the local port 320B becomes about 3 dB or less.

  Next, light having a wavelength of 1550 nm is incident on the local port 320B from the opposite end face of the optical fiber 920B subjected to coarse alignment as an alignment optical signal. While most of the alignment optical signal incident on the local port 320B is input to the optical interference unit 700B, a part thereof is emitted from the signal port 310B via the adjustment route 800B. Here, when 20 mW of 1550 nm light (optical signal for alignment) is incident from the local port 320B, approximately 100 μW of light is emitted from the signal port 310B. This value is a value that takes into account the total waveguide branch loss 20 dB, the coupling loss 3 dB between the local port 320 B and the optical fiber 920 B, and the loss 3 dB in the spatial propagation unit 830 B.

  Then, the optical intensity of the optical signal for alignment output from the opposite end face of the optical fiber 910B subjected to coarse alignment is measured with an optical power meter, and the optical fiber 910B is positioned at the position where the measured value is maximized. Further, the optical fiber 920B is positioned at a position where the light intensity measured by the power meter is maximized.

  After the optical fibers 910B and 920B are aligned with the signal port 310B and the local port 320B, the space propagation part 830B is filled with the light absorbing gel 850B. By filling the space propagation part 830B with the light absorbing gel 850B, the signal port 310B side and the local port 320B side are optically disconnected.

  Even in the PLC 100B configured as described above, an optical signal for alignment is input from one optical fiber, and the optical intensity of the optical signal for alignment emitted from the other optical fiber is measured. Based on the measured intensity value, the PLC 100B and the optical fibers 910B and 920B can be aligned with high accuracy.

  In the above-described PLC, it is desirable to dispose a lens between the optical fiber and the input port in order to reduce the coupling loss with the optical fiber. A top view in this case is shown in FIG. Since the configuration is the same as that of the PLC 100B shown in FIG. 4 except that the lenses 930C and 940C are disposed between the optical fibers 910C and 920C and the input ports 310C and 320C of the PLC 100C, detailed description thereof is omitted.

  The present invention is not limited to the above-described embodiment, and design changes and the like within a range not departing from the gist of the present invention are included in the present invention.

10, 10B planar optical waveguide 20, 20B substrate 31, 31B first input port 32, 32B second input port 40, 41B-48B output port 51, 51B first coupler 52, 52B second coupler 60, 60B processing unit 70, 70B Spatial propagation part 81, 82, 81B, 82B Optical fiber 83, 83B Optical component 90B Optical receiver 100 PLC
200 Substrate 310, 320 Input port 410, 420 Output port 510, 520 Optical waveguide for input 610, 620 Optical waveguide for output 700 Optical interference part 800 Adjustment route 811, 812 Coupler 821, 822 Optical waveguide for connection 830 Spatial propagation part 840 Matching oil 850 Light absorbing gel 910, 920 Optical fiber

Claims (10)

A substrate,
A first input port and a second input port, which are located on one end surface of the substrate and into which input light is incident;
An output port located on the other end surface of the substrate and emitting output light;
A first coupler and a second coupler which are formed on the substrate and which branch out the input light input from the first input port and the second input port, respectively;
A processing unit formed on the substrate and processing one input light output from the first coupler and the second coupler to output as output light;
The other input light formed on the substrate and output from the first coupler propagates to the second coupler side, and the other input light output from the second coupler propagates to the first coupler side. A spatial propagation unit to
A planar optical waveguide comprising: The input light is incident from the first optical fiber and the second optical fiber to the first input port and the second input port, respectively.
The spatial propagation unit is filled with a light shielding member that shields input light input to the spatial propagation unit after alignment of the first optical fiber and the first input port, and the second optical fiber and the second input port. The
The planar optical waveguide according to claim 1. The space propagation part is a recess formed on the substrate,
The light shielding member is a light absorbing gel or a light shielding plate that absorbs light in the wavelength band of the input light.
The planar optical waveguide according to claim 1 or 2. The first coupler and the second coupler output about 9/10 of input light as the one input light to the processing unit, and about 1/10 of the input light as the other input light. The planar optical waveguide according to any one of claims 1 to 3, wherein the planar optical waveguide is output to. The processor is
A polarization beam splitter for branching and outputting one input light output from the first coupler into two polarization components;
A splitter that divides and outputs one input light output from the second coupler;
A hybrid that outputs the output light by causing the optical signal output from the polarization beam splitter to interfere with the optical signal output from the splitter;
The planar optical waveguide according to claim 1, comprising: Comprising 8 said output ports,
The output light output from the hybrid is emitted from the eight output ports, respectively.
The planar optical waveguide according to claim 5. 7. The apparatus further comprises a first lens and a second lens that are arranged to face the first input port and the second input port and condense the input light to the first input port and the second input port, respectively. A planar optical waveguide according to any one of the above. A first optical fiber that makes signal light incident on the first input port as the input light;
A second optical fiber that causes local light to enter the second input port as the input light;
A planar optical waveguide according to any one of claims 1 to 7,
A light receiving element disposed on the other end surface side of the substrate of the planar optical waveguide and receiving output light output from the processing unit;
An optical receiver comprising: Forming a first input port and a second input port on one end surface of the substrate;
On the upper surface of the substrate,
A processing unit;
A spatial propagation section;
A first coupler connecting the first input port, the processing unit and the spatial propagation unit;
Forming a second coupler connecting the second input port, the processing unit and the spatial propagation unit;
A first optical fiber and a second optical fiber are disposed opposite to the first input port and the second input port, respectively;
Injecting alignment light from the second optical fiber into the second input port, and measuring the light intensity of alignment light emitted from the first optical fiber via the spatial propagation unit,
Positioning the first optical fiber and the second optical fiber at a position where the measured light intensity is maximum;
A method for aligning a planar optical waveguide. The first optical fiber and the second optical fiber allow visible light to enter the first optical fiber and the second optical fiber, and the center of the visible light and the centers of the first input port and the second input port are approximately. The method for aligning a planar optical waveguide according to claim 9, wherein the planar optical waveguide is arranged to face each other at a matching position.

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