JP2006047783A - Optical multiplexer/demultiplexer and optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical multiplexer/demultiplexer with which loss can be made small. <P>SOLUTION: An optical multiplexer/demultiplexer 100 is equipped with a member 110 on which optical waveguides 111 to 114 and a groove 115 are formed and an optical filter 120 which is inserted into the groove 115. The member 110 is a planar waveguide on one surface of which the optical waveguides 111 to 114 are formed and the groove 115 is formed on the surface. Before the formation of the groove 115, the optical waveguide 111 and the optical waveguide 114 are continuous optical waveguides and the optical waveguide 112 and the optical waveguide 113 are continuous optical waveguides. The a straight line-shaped groove 115 is formed so as to pass intersecting points of these two continuous optical waveguides. The optical waveguides 111 and 114 are in the shape of a straight line on the member 110. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical transmission system that transmits signal light having a plurality of wavelengths, and an optical multiplexer / demultiplexer used in such an optical transmission system.

In an optical transmission system that transmits signal light of a plurality of wavelengths, an optical multiplexer / demultiplexer that combines or demultiplexes the signal lights of a plurality of wavelengths is used. Particularly, in an optical transmission system (FTTH: fiber to the home) between a terminal station and a subscriber's home, an optical multiplexer / demultiplexer is required to be small and inexpensive. For example, in an optical multiplexer / demultiplexer described in Non-Patent Document 1, two optical waveguides are formed so as to cross each other on a substrate, and a V-groove is formed so as to pass through the crossing portion. An optical filter is inserted and fixed with an adhesive. In this optical multiplexer / demultiplexer, light having a certain wavelength out of the light that has been guided through one optical waveguide and reached the V-groove passes through the optical filter and is further guided through the optical waveguide. The light having the wavelength is reflected by the optical filter and guided through the other optical waveguide.
M. Yanagisawa, et al., "Low-loss and compact TFF-embedded silica-waveguide WDM filter for video distribution services in FTTH systems", OFC2004, TuI4

  The optical multiplexer / demultiplexer described in Non-Patent Document 1 is generally used in such a manner that each optical waveguide is optically coupled to the optical fiber array at the substrate end face, so that the optical axes of the optical waveguides are parallel to each other at the substrate end face. It is preferable that Therefore, in the optical multiplexer / demultiplexer described in this document, all the optical waveguides have a curved portion.

  However, if the optical waveguide has a curved portion, a part of the light guided through the optical waveguide leaks outside at the curved portion, so that loss easily occurs. This loss increases as the wavelength of the guided light is longer and the curvature radius of the curved portion is smaller. In particular, if the optical multiplexer / demultiplexer is to be miniaturized, the radius of curvature of the curved portion is inevitably reduced, which increases the problem of increased loss.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical multiplexer / demultiplexer capable of reducing loss and an optical transmission system including such an optical multiplexer / demultiplexer. And

  In the optical multiplexer / demultiplexer according to the present invention, the optical filter is inserted into the groove formed on the member, and the first optical waveguide and the second optical waveguide reach the groove on the first side with respect to the groove on the member. The third optical waveguide is provided on the member on the second side with respect to the groove until the third optical waveguide reaches the groove, the first optical waveguide or the second optical waveguide is linear on the member, and the optical filter Of the light propagating through the first optical waveguide and emitted to the groove, the light transmitted through the optical filter is incident on the third optical waveguide, and the light reflected by the optical filter is incident on the second optical waveguide. And Here, the optical filter is preferably a dielectric multilayer filter.

  In this optical multiplexer / demultiplexer, since the first optical waveguide or the second optical waveguide is linear on the member, the long-wavelength light is guided in the linear optical waveguide, while the optical waveguide having the curved portion. By guiding short-wavelength light through the waveguide, loss during optical multiplexing / demultiplexing can be suppressed.

  In the optical multiplexer / demultiplexer according to the present invention, it is preferable that the first optical waveguide, the second optical waveguide, the third optical waveguide, and the optical filter are provided as a set, and a plurality of these sets are provided. At this time, it is preferable that the optical waveguide on the same side with respect to the optical filter is provided on the common member. Moreover, it is preferable that the optical filter is integrated with respect to a plurality of sets. In addition, it is preferable that the optical axes of the optical waveguides on the same side with respect to the optical filter are parallel to each other in the vicinity of the end face of the member.

  In the optical multiplexer / demultiplexer according to the present invention, the planar shape of the first side of the member includes a first side facing the optical filter, a second side opposite to the first side, and a third parallel to each other. A rectangular shape having a side and a fourth side, and the third side and the fourth side are parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, It is preferred that the second side is vertical. Alternatively, the planar shape of the first side of the member includes a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. The third side and the fourth side are parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side to the first side Are preferably parallel.

  An optical transmission system according to the present invention is an optical transmission system that transmits signal light having a plurality of wavelengths, and includes the above-described optical multiplexer / demultiplexer according to the present invention, and the signal light having a plurality of wavelengths is multiplexed by the optical multiplexer / demultiplexer. Alternatively, it is characterized by demultiplexing. In addition, signal light having a first wavelength of a plurality of wavelengths is guided to one of the first optical waveguide and the second optical waveguide that is linearly provided, and one of the plurality of wavelengths is guided to the other optical waveguide. It is preferable to guide signal light having a second wavelength shorter than the first wavelength.

  The optical multiplexer / demultiplexer according to the present invention can reduce loss.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  (First embodiment of optical multiplexer / demultiplexer)

  First, a first embodiment of an optical multiplexer / demultiplexer according to the present invention will be described. FIG. 1 is a perspective view of an optical multiplexer / demultiplexer 100 according to the first embodiment. FIG. 2 is a plan view of the optical multiplexer / demultiplexer 100 according to the first embodiment. The optical multiplexer / demultiplexer 100 shown in these drawings includes a member 110 in which optical waveguides 111 to 114 and a groove 115 are formed, and an optical filter 120 inserted in the groove 115.

The member 110 is a planar waveguide in which optical waveguides 111 to 114 are formed on one surface, and a groove 115 is formed on the surface. Before the groove 115 is formed, the optical waveguide 111 and the optical waveguide 114 are continuous optical waveguides, and the optical waveguide 112 and the optical waveguide 113 are continuous optical waveguides. And the linear groove | channel 115 is formed so that the intersection of these two continuous optical waveguides may be passed. For example, the member 110 is formed by forming a clad made of quartz glass and a core made of quartz glass doped with GeO ₂ on a substrate made of quartz glass or silicon. This core becomes an optical waveguide.

  The optical waveguides 111 and 112 are provided on the member 110 until reaching the groove 115 on the first side with respect to the groove 115. The optical waveguides 113 and 114 are provided on the member 110 on the second side with respect to the groove 115 until reaching the groove 115. The optical waveguides 111 and 114 are linear on the member 110. On the other hand, the optical waveguides 112 and 113 have a curved portion on the member 110.

The optical filter 120 inserted into the groove 115 is a dielectric multilayer filter, and is fixed in the groove 115 with an adhesive. The optical filter 120, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R. For example, the transmission wavelength λ _T is 1.55 μm and the reflection wavelength λ _R is 1.31 μm and 1.49 μm, but is not limited thereto.

Then, for example, the optical filter 120, out of the light emitted in the groove 115 of the optical waveguide 111 come into guided, is guided light of wavelength lambda _T transmitted through the optical filter 120 in the optical waveguide 114, optical filter 120 in to guide light to the optical waveguide 112 of the reflected wavelength lambda _R. Namely, in this case, the optical demultiplexer 100 may demultiplex the light of the light and the wavelength lambda _R of the wavelength lambda _T.

Further, for example, the optical filter 120, by transmitting light emitted wavelength lambda _T through the optical waveguide 114 in the groove 115 come into guided, to guide light having the wavelength lambda _T to the optical waveguide 111. Further, the optical filter 120, an optical waveguide 112 come into guided by reflecting light of the emitted wavelength lambda _R in the groove 115, thereby guiding the light having the wavelength lambda _R the optical waveguide 111. That is, the optical multiplexer 100 may multiplex the light of the light and the wavelength lambda _R of the wavelength lambda _T.

  This optical multiplexer / demultiplexer 100 can be used in various ways because two optical waveguides are formed on both sides of the optical filter 120, but even if only one optical waveguide is formed on one side. Good.

  In general, when the optical waveguide is curved, the longer the wavelength of the guided light, the greater the propagation loss of the guided light. However, in this optical multiplexer / demultiplexer 100, the optical waveguides 111 and 114 are formed linearly. Therefore, when the optical multiplexer / demultiplexer 100 is used, long-wavelength light is guided in the linear optical waveguides 111 and 114, while short-wavelength light is guided in the optical waveguides 112 and 113 having curved portions. It is preferable to guide the light, and by doing so, it is possible to suppress loss during optical multiplexing / demultiplexing.

  Further, the distance between the end faces of the optical waveguides 111 and 112 in the groove 115 and the optical filter 120 is preferably 3 μm or less, and the end face of the optical waveguides 113 and 114 in the groove 115 and the optical filter 120 It is preferable that the distance between them is 3 μm or less. By doing in this way, the loss in the case of optical multiplexing / demultiplexing is reduced.

  Further, the mode field diameter of each of the optical waveguides 111 to 114 in the groove 115 is preferably larger than the mode field diameter of a normal single mode optical fiber, for example, 20 μm or more. Thus, by increasing the mode field diameter of the optical waveguide at the end face facing the optical filter 120, it is possible to suppress the influence of diffraction in the optical filter 120, and to suppress the loss at the time of multiplexing / demultiplexing. Can do. Actually, by conducting beam propagation analysis, etc., considering the incident angle of light to the optical filter 120, the loss in the optical waveguide, the influence of higher order modes, etc., the mode field diameter of the optical waveguide at the end face It is necessary to select an optimum value.

  The planar shape on the side where the optical waveguides 111 and 112 are formed on the member 110 has a first side facing the optical filter 120 (side on the groove 115 side), and a second side opposite to the first side. And a rectangular shape having a third side and a fourth side parallel to each other, the third side and the fourth side are parallel to the linearly provided optical waveguide 111, and the second side is It is vertical. Further, the first side is not parallel to the second side. In this case, since the linear optical waveguide 111 is vertical on the end face of the substrate, it is convenient for coupling the optical fiber and the optical waveguide 111, for example. The same applies to the planar shape on the side where the optical waveguides 113 and 114 are formed on the member 110.

  (Second embodiment of optical multiplexer / demultiplexer)

  Next, a second embodiment of the optical multiplexer / demultiplexer according to the present invention will be described. FIG. 3 is a plan view of the optical multiplexer / demultiplexer 200 according to the second embodiment. The optical multiplexer / demultiplexer 200 shown in this figure has a configuration in which four sets of optical multiplexer / demultiplexers are arranged in parallel. The optical multiplexer / demultiplexer 200 includes a member 210 and an optical filter 220.

The member 210 is a planar waveguide having optical waveguides 211 _{1 to} 211 ₄ , 212 _{1 to} 212 ₄ , 213 _{1 to} 213 ₄ , and 214 _{1 to} 214 ₄ formed on _one surface thereof, and a groove 215 is formed on the surface. Is formed. Before the formation of the grooves 215, the optical waveguide 211 _n and the optical waveguide 214 _n are optical waveguide continuously, the optical waveguide 212 _n and the optical waveguide 213 _n is an optical waveguide which is continuous. Here, the subscript n is an arbitrary integer from 1 to 4. A linear groove 215 is formed so as to pass through the intersection of these two continuous optical waveguides. The member 210 is formed by, for example, forming a clad made of quartz glass and a core made of quartz glass to which GeO ₂ is added on a substrate made of quartz glass or silicon. This core becomes an optical waveguide.

The optical waveguides 211 _n and 212 _n are provided on the member 210 on the first side with respect to the groove 215 until reaching the groove 215. The optical waveguides 213 _n and 214 _n are provided on the member 210 on the second side with respect to the groove 215 until reaching the groove 215. The optical waveguides 211 _n and 214 _n are linear on the member 210. On the other hand, the optical waveguides 212 _n and 213 _n have a curved portion on the member 210.

The optical filter 220 inserted into the groove 215 is a dielectric multilayer filter, and is fixed in the groove 215 with an adhesive. The optical filter 220, while transmitting light of a certain wavelength lambda _T, to reflect light of other wavelengths lambda _R. For example, the transmission wavelength λ _T is 1.55 μm and the reflection wavelength λ _R is 1.31 μm and 1.49 μm, but is not limited thereto.

In this optical multiplexer / demultiplexer 200, each set of optical waveguides 211 _n , 212 _n , 213 _n , 214 _n and the optical filter 220 have substantially the same configuration as the optical multiplexer / demultiplexer 100 and operate in substantially the same manner.

One member 210 on the 16 optical waveguides ₂₁₁ 1-211 _{4, 212} 1 to 212 _{4, 213} 1 to 213 _{4, 214} 1 to 214 ₄ are formed. From this, the manufacturing cost per channel in the member 210 can be reduced. In addition, the optical filters 120 may be provided separately for each group, but it is preferable to provide the optical filters 120 integrated with respect to the four groups. In the latter case, the optical multiplexer / demultiplexer 200 is provided. It can be manufactured at low cost.

Member 210 on the eight optical waveguides ₂₁₁ 1-211 _{4, 212} 1 to 212 ₄ is preferred that a constant spacing be parallel to one another in each of the optical axes end face, also, eight on the member 210 it is preferred that a constant spacing be parallel to one another in the optical waveguide ₂₁₃ 1-213 _{4, 214} 1 to 214 ₄ end surface each of the optical axis of the. In this case, the member 210 and the optical fiber array can be aligned and joined together.

The planar shape on the side where the optical waveguides 211 _n and 212 _n are formed on the member 210 has a first side (side on the groove 215 side) facing the optical filter 220 and a second side opposite to the first side. A rectangular shape having a side and a third side and a fourth side parallel to each other, and each of the third side and the fourth side is parallel to the optical waveguide 211 _n provided in a straight line, The second side is parallel to the side. In this case, the waveguide lengths of the optical waveguides 211 _{1 to} 211 ₄ can be set to constant values, and the waveguide lengths of the optical waveguides 212 _{1 to} 212 ₄ can also be set to constant values. The same applies to the planar shape on the side where the optical waveguides 213 _n and 214 _n are formed on the member 210.

  (First Embodiment of Optical Transmission System)

  Next, a first embodiment of the optical transmission system according to the present invention will be described. FIG. 4 is a configuration diagram of the optical transmission system 1 according to the first embodiment. The optical transmission system 1 shown in this figure is an FTTH (fiber to the home) system that transmits and receives signal light bidirectionally between a station 10 and subscriber homes 21 to 23.

In the station 10, data transmission devices 11 _{1 to} 11 ₃ , video signal transmitters 12 _{1 to} 12 ₃ and an optical multiplexer / demultiplexer 13 are provided. Each of the data transmission devices 11 _{1 to} 11 ₃ is connected to the Internet and transmits / receives digital data to / from the subscriber homes 21 to 23. Each of the video signal transmitters 12 _{1 to} 12 ₃ transmits a video signal (analog data) to the subscriber homes 21 to 23. The wavelength of the signal light transmitted from the subscriber's home 21 to 23 to the data transmission device ₁₁ 1 to 11 ₃ is 1.31 .mu.m, the signal sent from the data transmission device ₁₁ 1 to 11 ₃ to the subscriber's home 21 to 23 The wavelength of the light is 1.49 μm, and the wavelength of the signal light transmitted from the video signal transmitters 12 _{1 to} 12 ₃ to the subscriber homes 21 to 23 is 1.55 μm.

The optical multiplexer / demultiplexer 13 provided in the station 10 multiplexes / demultiplexes signal light of three wavelengths transmitted / received by the data transmission apparatuses 11 _{1 to} 11 ₃ and the video signal transmitters 12 _{1 to} 12 ₃ . As the optical multiplexer / demultiplexer 13, the optical multiplexer / demultiplexer of each of the embodiments described above is used, and among them, the optical multiplexer / demultiplexer 200 in which a plurality of sets of optical multiplexer / demultiplexers are arranged in parallel can be particularly preferably used.

  An optical receiver 41 is provided in the subscriber's home 21, and an optical multiplexer / demultiplexer 51 is provided in the optical receiver 41. Other subscriber homes 22 and 23 are also provided with optical receivers. Further, a star coupler 30 is provided in the vicinity of the subscriber homes 21 to 23. This star coupler 30 branches the signal light (wavelength 1.49 μm, 1.55 μm) transmitted from the station 10, sends each branched signal light to the subscriber homes 21 to 23, and joins it. Signal light (wavelength: 1.33 μm) transmitted from the side of the user's homes 21 to 23 is sent to the station 10. The optical multiplexer / demultiplexer 51 multiplexes / demultiplexes signal light of three wavelengths, and the optical multiplexer / demultiplexer of each embodiment described above is used.

In this optical transmission system 1, the signal light (wavelength 1.49 μm, 1.55 μm) output from the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is branched by the star coupler 30, the branched signal light is demultiplexed by the optical multiplexer / demultiplexer 51 in the optical receiver 41, and one of the demultiplexed signal lights (wavelength) 1.49 μm) is transmitted to the personal computer in the subscriber's house 21, and the other signal light (wavelength 1.55 μm) is transmitted to the television receiver in the subscriber's house 21. The signal light (wavelength 1.33 μm) transmitted from the personal computer in the subscriber's home 21 passes through the optical multiplexer / demultiplexer 51 in the optical receiver 41, the star coupler 30, and the optical multiplexer / demultiplexer 13 in the station 10. Received by the transmission device 11 _n .

  In the present embodiment, since the optical multiplexer / demultiplexer of each of the embodiments described above is used as the optical multiplexer / demultiplexers 13 and 52, loss during the multiplexing / demultiplexing is small, and high-quality signal light transmission is possible. is there.

  (Second Embodiment of Optical Transmission System)

  Next, a second embodiment of the optical transmission system according to the present invention will be described. FIG. 5 is a configuration diagram of the optical transmission system 2 according to the second embodiment. The optical transmission system 2 shown in this figure is an FTTH system that transmits and receives signal light bidirectionally between the station 10 and the subscriber homes 21 and 22 in the apartment 20. Compared with the optical transmission system 1 (FIG. 4) according to the first embodiment, the optical transmission system 2 according to the second embodiment is such that the subscriber homes 21 and 22 are apartment houses in the apartment 20, and The difference is that one optical receiver 40 is provided for the apartment 20.

  An optical multiplexer / demultiplexer 50 is provided in the optical receiver 40 provided in the apartment 20. This optical multiplexer / demultiplexer 50 multiplexes / demultiplexes signal light of three wavelengths, and the optical multiplexer / demultiplexer of each embodiment described above is used. Among them, a plurality of sets of optical multiplexer / demultiplexers are arranged in parallel. The optical multiplexer / demultiplexer 200 can be used particularly preferably. The star coupler 30 may be provided in the optical receiver 40.

In the optical transmission system 2, signal light (wavelengths 1.49 μm and 1.55 μm) output from the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is branched by the star coupler 30, and the branched signal light is demultiplexed by the optical multiplexer / demultiplexer 50 in the optical receiver 40, and one of the demultiplexed signal lights (wavelength). 1.49 μm) is transmitted to a personal computer in each subscriber's house, and the other signal light (wavelength 1.55 μm) is transmitted to a television receiver in each subscriber's house. The signal light (wavelength 1.33 μm) transmitted from the personal computer in each subscriber's home passes through the optical multiplexer / demultiplexer 50 in the optical receiver 40, the star coupler 30, and the optical multiplexer / demultiplexer 13 in the station 10 to transmit data. Received by device _11n .

  (Third embodiment of optical transmission system)

  Next, a third embodiment of the optical transmission system according to the present invention will be described. FIG. 6 is a configuration diagram of the optical transmission system 3 according to the third embodiment. The optical transmission system 3 shown in this figure is an FTTH system that transmits and receives signal light bidirectionally between the station 10 and the subscriber homes 21 and 22 in the apartment 20. Compared with the optical transmission system 2 (FIG. 5) according to the second embodiment, the optical transmission system 3 according to the third embodiment is provided with the star couplers 31 and 32 and the optical multiplexer / demultiplexer 50 in the optical receiver 40. Is different.

In this optical transmission system 3, signal light (wavelength 1.49 μm, 1.55 μm) output from each of the data transmission device 11 _n and the video signal transmitter 12 _n in the station 10 is combined by the optical multiplexer / demultiplexer 13. Waved and sent out. The signal light transmitted from the station 10 is demultiplexed by the optical multiplexer / demultiplexer 50 in the optical receiver 40. One signal light (wavelength 1.49 μm) demultiplexed by the optical multiplexer / demultiplexer 50 is branched by the star coupler 31 and transmitted to a personal computer in each subscriber's home, and the other signal light (wavelength 1.55 μm) is star-coupled. The data is branched by the coupler 32 and transmitted to the television receiver in each subscriber's house. The signal light (wavelength 1.33 μm) transmitted from the personal computer in each subscriber's house passes through the star coupler 31 and the optical multiplexer / demultiplexer 50 in the optical receiver 40 and the optical multiplexer / demultiplexer 13 in the station 10 for data transmission. Received by device _11n .

1 is a perspective view of an optical multiplexer / demultiplexer 100 according to a first embodiment. 1 is a plan view of an optical multiplexer / demultiplexer 100 according to a first embodiment. It is a top view of the optical multiplexer / demultiplexer 200 which concerns on 2nd Embodiment. 1 is a configuration diagram of an optical transmission system 1 according to a first embodiment. FIG. It is a block diagram of the optical transmission system 2 which concerns on 2nd Embodiment. It is a block diagram of the optical transmission system 3 which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1-3 ... Optical transmission system, 10 ... Station, 11 ... Data transmission apparatus, 12 ... Video signal transmitter, 13 ... Optical multiplexer / demultiplexer, 20 ... Condominium, 21-23 ... Subscriber's house, 30-32 ... Star coupler , 40, 41 ... optical receiver, 50, 51 ... optical multiplexer / demultiplexer, 100 ... optical multiplexer / demultiplexer, 110 ... member, 111-114 ... optical waveguide, 115 ... groove, 120 ... optical filter, 200 ... optical multiplexer / demultiplexer 210, member, 211-214, optical waveguide, 215, groove, 220, optical filter.

Claims (10)

An optical filter is inserted into a groove formed on the member, and provided on the member on the first side with respect to the groove until the first optical waveguide and the second optical waveguide reach the groove. A third optical waveguide is provided on the second side of the groove until reaching the groove;
The first optical waveguide or the second optical waveguide is linear on the member;
Of the light that has propagated through the first optical waveguide and emitted to the groove, the optical filter causes the light transmitted through the optical filter to enter the third optical waveguide, and the light reflected by the optical filter is Incident on the second optical waveguide,
An optical multiplexer / demultiplexer characterized by that.   2. The optical multiplexer / demultiplexer according to claim 1, wherein the optical filter is a dielectric multilayer filter.   2. The optical multiplexer / demultiplexer according to claim 1, wherein a plurality of sets of the first optical waveguide, the second optical waveguide, the third optical waveguide, and the optical filter are provided.   4. The optical multiplexer / demultiplexer according to claim 3, wherein an optical waveguide on the same side with respect to the optical filter is provided on a common member.   4. The optical multiplexer / demultiplexer according to claim 3, wherein the optical filter is integrated with the plurality of sets.   4. The optical multiplexer / demultiplexer according to claim 3, wherein the optical axes of the optical waveguides on the same side with respect to the optical filter are parallel to each other in the vicinity of the end face of the member. The planar shape of the first side of the member includes a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. A rectangle having
The third side and the fourth side are each parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side is vertical.
The optical multiplexer / demultiplexer according to claim 1. The planar shape of the first side of the member includes a first side facing the optical filter, a second side opposite to the first side, and a third side and a fourth side parallel to each other. A rectangle having
Each of the third side and the fourth side is parallel to the linearly provided optical waveguide of the first optical waveguide and the second optical waveguide, and the second side with respect to the first side Are parallel,
The optical multiplexer / demultiplexer according to claim 1.   An optical transmission system for transmitting signal light of a plurality of wavelengths, comprising the optical multiplexer / demultiplexer according to any one of claims 1 to 8, wherein the signal light of the plurality of wavelengths is multiplexed by the optical multiplexer / demultiplexer. An optical transmission system characterized by demultiplexing.   Of the first optical waveguide and the second optical waveguide, one optical waveguide provided in a straight line is guided with the signal light having the first wavelength of the plurality of wavelengths, and the other optical waveguide has the plurality of wavelengths. The optical transmission system according to claim 9, wherein signal light having a second wavelength shorter than the first wavelength is guided.

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