JP3855773B2 - Optical multiplexer / demultiplexer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical multiplexer / demultiplexer that multiplexes or demultiplexes wavelength-multiplexed optical signals in order to transmit and receive optical signals communicated by, for example, an optical fiber.
[0002]
[Prior art]
In recent years, communication using optical fibers has become mainstream due to the development of high-speed and large-capacity communication networks and communication control devices. For example, terminal devices such as information home appliances installed in each home are also connected to the Internet using optical fibers. There is a need to connect a communication network to transmit and receive signals. Optical fibers are also being used to connect personal computers installed in homes to televisions, DVDs, game machines, and the like. Therefore, there is a need for an inexpensive, small-sized and efficient optical transceiver that can be used in information appliances. Such an optical transceiver includes an optical multiplexer / demultiplexer that demultiplexes or multiplexes wavelength-multiplexed optical signals in order to transmit and receive optical signals communicated by optical fibers.
[0003]
By the way, in such an optical multiplexer / demultiplexer, many structures have been proposed in which a filter is provided in association with an optical waveguide to demultiplex or multiplex optical signals. In many cases, a filter is mounted in an optical waveguide on a substrate, and a conventional optical multiplexer / demultiplexer (see FIG. 1 to be described later) for demultiplexing or multiplexing an optical signal is attached to the end face of the optical waveguide on the substrate. There is a conventional optical multiplexer / demultiplexer (see FIG. 2 described later) for demultiplexing or multiplexing optical signals.
[0004]
FIG. 1 is a plan view showing a schematic configuration of the above-described conventional optical multiplexer / demultiplexer. The optical multiplexer / demultiplexer 1 includes optical waveguides 3, 4, and 5 formed on a substrate 2 and a filter 6 that is mounted perpendicular to the substrate 2, and one end of the optical waveguides 3 and 4 is connected to the filter 6. The optical waveguide 5 is coupled on one side, and the end of the optical waveguide 5 faces the coupling portion of the optical waveguides 3 and 4 through the filter 6. Further, outside the optical multiplexer / demultiplexer 1, an optical fiber 7 is optically connected to the other end of the optical waveguide 3, and an optical fiber 8 is optically connected to the other end of the optical waveguide 4. An optical fiber 9 is optically connected to the other end. Since the incident angles of light with respect to the surface of the filter 6 of the optical waveguide 3 and the optical waveguide 4 are respectively θ = 45 ° with respect to the perpendicular 10 standing on the filter 6, The angle formed by the optical waveguide 4 is 90 °.
[0005]
Now, the wavelength multiplexed signal (or optical signal) including the optical signal b in the wavelength band reflected by the filter 6 and the optical signal c in the wavelength band transmitted through the filter 6 is transmitted through the optical fiber 7. b or any one of the optical signals c may be arbitrarily propagated.) If the optical signal a propagates through the optical waveguide 3 and reaches the filter 6, it is included in the optical signal a. Of the optical signals, the optical signal b is reflected by the filter 6 and enters the optical waveguide 4, propagates through the optical waveguide 4, and is coupled to the optical fiber 8. On the other hand, among the optical signals included in the optical signal a, the optical signal c passes through the filter 6 and enters the optical waveguide 5, propagates through the optical waveguide 5, and is coupled to the optical fiber 9. Therefore, in this case, the optical multiplexer / demultiplexer 1 functions to demultiplex the optical signal a.
[0006]
On the other hand, when the optical signal b in the wavelength region reflected by the filter 6 enters the optical waveguide 4 from the optical fiber 8 and propagates through the optical waveguide 4 and reaches the filter 6, the optical signal b is reflected by the filter 6. Into the optical waveguide 3. Further, when the optical signal c in the wavelength region that passes through the filter 6 enters the optical waveguide 5 from the optical fiber 9, propagates through the optical waveguide 5 and reaches the filter 6, the optical signal c passes through the filter 6 and passes through the optical waveguide. Enter 3 As a result, the wavelength-multiplexed optical signal a obtained by combining the optical signal b and the optical signal c is propagated to the optical waveguide 3 and coupled to the optical fiber 7. Therefore, in this case, the optical multiplexer / demultiplexer 1 functions to multiplex the optical signal b and the optical signal c.
[0007]
FIG. 2 is a plan view showing a schematic configuration of another conventional optical multiplexer / demultiplexer described above. The optical multiplexer / demultiplexer 11 includes optical waveguides 13 and 14 formed on a substrate 12 and a filter 16 attached to an end surface of the substrate 12. One end of the optical waveguides 13 and 14 is on one side of the filter 6. So that the end face of the optical fiber 19 faces the other face of the filter 16. Further, outside the optical multiplexer / demultiplexer 11, an optical fiber 17 is optically connected to the other end of the optical waveguide 13, and an optical fiber 18 is optically connected to the other end of the optical waveguide 14. The incident angles of light with respect to the surface of the filter 16 of the optical waveguide 13 and the optical waveguide 14 are respectively θ = 45 ° with respect to the perpendicular 15 standing on the filter 16. The angle formed by the optical waveguide 14 is 90 °.
[0008]
This optical multiplexer / demultiplexer 11 also functions in the same manner as the optical multiplexer / demultiplexer 1. That is, the wavelength multiplexed signal a (or the optical signal b or the optical signal c is arbitrary, including the optical signal b in the wavelength region reflected by the filter 6 and the optical signal c in the wavelength region transmitted through the filter 6. ) Propagates through the optical waveguide 13 and reaches the filter 16, among the optical signals included in the optical signal a, the optical signal b is reflected by the filter 16 and enters the optical waveguide 14. Then, it propagates through the optical waveguide 14 and is coupled to the optical fiber 18. On the other hand, among the optical signals included in the optical signal a, the optical signal c passes through the filter 16 and enters the optical fiber 19. This is the function of demultiplexing.
[0009]
On the other hand, when the optical signal b in the wavelength region reflected by the filter 16 enters the optical waveguide 14 from the optical fiber 18 and propagates through the optical waveguide 14 and reaches the filter 16, the optical signal b is reflected by the filter 6. Into the optical waveguide 13. Further, when the optical signal c in the wavelength region that passes through the filter 6 is emitted from the optical fiber 19, the optical signal c passes through the filter 6 and enters the optical waveguide 13. As a result, the multiplexed optical signal a obtained by combining the optical signal b and the optical signal c is propagated through the optical waveguide 13 and coupled to the optical fiber 7. This is the function of multiplexing.
[0010]
[Problems to be solved by the invention]
However, in the conventional optical multiplexer / demultiplexer as described above, the optical signal reflected from the filter is incident on the side reflecting the optical signal after entering the optical signal from the optical waveguide at an incident angle of 45 ° with respect to the filter. Are incident on different optical waveguides, the ends of the two optical waveguides are arranged at an angle of about 90 ° on the main surface of the substrate at the joint location of the two optical waveguides. As a result, the optical fiber optically connected to the end face of the optical waveguide and the optical elements such as the light emitting element and the light receiving element are physically separated. Such an arrangement causes a problem that not only the space of the optical waveguide but also the optical multiplexer / demultiplexer itself becomes large.
[0011]
In order to avoid this, in the conventional optical multiplexer / demultiplexer, the optical waveguide is bent with a large curvature so that optical elements such as optical fibers can be arranged as close as possible. However, if the curvature of the optical waveguide becomes too large Light propagation loss occurs, and the propagation efficiency of the optical signal is reduced.
[0012]
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the problems of the conventional example described above, and an object of the present invention is to make it possible to configure a structure of an optical waveguide for demultiplexing or multiplexing light in a small space. An object of the present invention is to provide an optical multiplexer / demultiplexer that can be miniaturized.
[0013]
  The optical multiplexer / demultiplexer according to the present invention forms an optical waveguide by filling a core material in each groove provided in two clad substrates,Two optical waveguides provided on the two clad substrates are optically separated from each other, and two optical waveguides are separated.The clad substrateThe surface on which the optical waveguide is formedA filter that transmits light in a predetermined wavelength region and reflects light in other wavelength regions is disposed opposite to the optical waveguide end surfaces of both cladding substrates, and is disposed on the end surfaces of the cladding substrates. An optical multiplexer / demultiplexer for demultiplexing light propagating in the optical waveguide by the filter, or for combining light propagating in the optical waveguide and light incident on the optical waveguide from the outside, One of the two clad substratesClad substrateThe first reflection surface that reflects light propagating through the optical waveguide toward the filter at the end, and the first reflection surface is located at the end of the optical waveguide where the filter is opposed to the first reflection surface. It is formed with an inclined surface with respect to the optical axis direction of the optical waveguide protruding inward so as to block the optical waveguide,Thereby, the end face of the optical waveguide on which the filter is opposed is exposed on the outer peripheral surface of one clad substrate with a relatively small area,Of the light reflected by the first reflecting surface, the light in the filter transmission wavelength region is transmitted through the filter and emitted to the outside, and the light reflected by the first reflection surface other than the filter transmission wavelength region The light in the wavelength region is reflected by the filter and is reflected on the other optical waveguide.End faceAnd the other of the two clad substrates.Clad substrateThe second reflection surface that reflects light propagating through the optical waveguide toward the filter is provided at the end, and the second reflection surface is formed at the end of the optical waveguide where the filter is opposed to the second reflection surface. It is formed with an inclined surface with respect to the optical axis direction of the optical waveguide protruding inward so as to block the optical waveguide,Thereby, the end face of the optical waveguide on which the filter is opposed is exposed on the outer peripheral surface of the other clad substrate with a relatively small area,Of the light reflected by the first reflecting surface, the filter transmission wavelength rangeWavelength range other thanIs reflected by the filter and the other optical waveguideEnd faceAnd is reflected by the second reflecting surface in a direction substantially parallel to the optical axis direction of the other optical waveguide.
[0014]
  In the optical multiplexer / demultiplexer according to the present invention, when light in the filter transmission wavelength region enters from the end face of one of the optical waveguides, this light is reflected by the first reflecting surface, reaches the filter, and passes through the filter. And exits to the outside. Light in the filter transmission wavelength region can also be propagated in the opposite direction. Also, when light in the filter reflection wavelength region enters from the end face of the optical waveguide, this light is reflected by the first reflection surface and reaches the filter, is reflected by the filter and enters the other optical waveguide, The light is emitted from the end face of the optical waveguide. The light in the filter reflection wavelength region can also be propagated in the opposite direction. Accordingly, optical components such as light emitting elements, light receiving elements, and optical fibers are disposed at positions facing both end faces of the optical waveguide and at positions corresponding to the filters, respectively, for optical demultiplexing, optical multiplexing, optical transceivers, etc. It can be used for
[0015]
  Moreover, the present inventionLight ofIn the multiplexer / demultiplexer, since the light propagating in the optical waveguide is reflected by the first reflecting surface, it is not necessary to largely bend the optical waveguide. In a preferred embodiment, the optical waveguide is linear. The optical multiplexer / demultiplexer can be downsized. Therefore, it is possible to reduce the size of the module including the optical component. In addition, since it is not necessary to bend the optical waveguide greatly, light hardly leaks from the optical waveguide, and the waveguide efficiency of the optical multiplexer / demultiplexer can be increased. Preferably, the clad substrates are bonded to each other with the filter interposed therebetween, and the filter is provided over the entire bonding region of the clad substrates. A manufacturing process can be facilitated by providing the filter over the entire bonding region between the clad substrates.
[0016]
  Furthermore, in the optical multiplexer / demultiplexer according to the present invention, since the light propagating in the optical waveguide is reflected by the second reflecting surface, it is not necessary to bend the optical waveguide greatly, and the optical multiplexer / demultiplexer Can be miniaturizedThe
[0017]
  The present inventionIn an embodiment of the optical multiplexer / demultiplexer,The first reflecting surface is formed in a curved shape.Yes.According to such an embodimentFirstBy forming the first reflecting surface into a curved surface, the first reflecting surface has a lens function, a condensing function, and the like.Butit can.
[0018]
  The present inventionIn another embodiment of the optical multiplexer / demultiplexer,The second reflecting surface is formed into a curved surfaceYes.According to such an embodimentFirstBy forming the second reflecting surface into a curved surface, the second reflecting surface has a lens function, a condensing function, and the like.Butit can.
[0019]
  In addition, the present inventionLight ofIn still another embodiment of the multiplexer / demultiplexer, the clad substrate is preferably formed of a resin, and the clad substrates are preferably bonded by an adhesive.
[0020]
  An optical communication apparatus according to the present invention is related to the present invention.LightA multiplexer / demultiplexer is used. Since such an optical communication device uses the optical multiplexer / demultiplexer of the present invention, there is no protrusion in the thickness direction and the thickness can be reduced.
[0021]
The above-described constituent elements of the present invention can be arbitrarily combined as much as possible.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 3 is a sectional view showing a schematic configuration of the optical multiplexer / demultiplexer 21 according to the first embodiment of the present invention. This optical multiplexer / demultiplexer 21 is formed by replicating, for example, a resin-made clad substrate 22 produced by injection molding, an optical waveguide 23 formed by filling a linear groove formed in the clad substrate 22 with a core material, And a filter 24 that is formed in a region including at least a part of the upper surface of the optical waveguide 23 and passes only an optical signal in a predetermined wavelength region. Further, in the portion of the optical waveguide 23 that faces the filter 24, a part of the bottom surface of the optical waveguide 23 (or the bottom surface of the groove) protrudes inward or upward so as to substantially block the optical waveguide 23. The inclined surfaces 28 are formed on both sides thereof. Both inclined surfaces 28 are symmetrical in the cross section shown in FIG. Further, the inclined surface 28 may be a flat surface, but in this embodiment, the inclined surface 28 is curved in a concave shape in cross section.
[0023]
FIG. 3 shows an example in which the optical multiplexer / demultiplexer 21 is used as an optical transceiver. That is, in this case, the light emitting element 25 realized by a semiconductor laser, a light emitting diode, or the like is disposed to face the end surface 23a of the optical waveguide 23 so as to be optically connected to the one end surface 23a of the optical waveguide 23. Yes. The optical fiber 27 serving as a transmission / reception signal transmission path is disposed to face the end surface 23b of the optical waveguide 23 so as to be optically connected to the other end surface 23b of the optical waveguide 23. The light receiving element 26 realized by a photodiode, a phototransistor, or the like is disposed on the upper surface of the optical waveguide 23, particularly above the inclined surface 28, through the filter 24.
[0024]
Next, the optical transceiver operation of the optical multiplexer / demultiplexer 21 will be described. A transmission signal emitted from the light emitting element 25 and incident on the optical waveguide 23 is an optical signal in a wavelength region (reflection wavelength region) that does not pass through the filter 24. Therefore, when a transmission signal is emitted from the light emitting element 25, the transmission signal propagates through the optical waveguide 23 as shown by a broken line arrow Y1. At this time, the transmission signal that hits the inclined surface 28 is totally reflected by the inclined surface 28 and enters the filter 24, but the transmission signal is reflected by the filter 24 and returns to the optical waveguide 23 again, and is totally reflected by the other inclined surface 28. Then, it propagates again through the optical waveguide 23 and enters the optical fiber 27.
[0025]
Further, the reception signal transmitted through the optical fiber 27 is an optical signal in a wavelength region that passes through the filter 24. Accordingly, the received signal transmitted from the optical fiber 27 enters the optical waveguide 23 and propagates in the optical waveguide 23. The received signal propagating through the optical waveguide 23 strikes the inclined surface 28, is totally reflected, enters the filter 24, passes through the filter 24, and is received by the light receiving element 26.
[0026]
According to the optical multiplexer / demultiplexer 21 of the present invention, the side on which the light is reflected by the filter 24 can be formed by one optical waveguide 23, in particular, a linear optical waveguide. Can be miniaturized. Further, in this embodiment, since the light receiving element 26 only needs to be mounted on the filter 24 even on the filter transmission side, the size of the module including the light receiving element 26 and the like can be extremely reduced. Further, according to the optical multiplexer / demultiplexer 21 of the present invention, since it is not necessary to bend the optical waveguide, there is no light propagation loss due to the bending of the optical waveguide, and the optical propagation loss can be reduced as a whole of the optical waveguide. . Further, in this embodiment, since the inclined surface 28 is curved in a concave shape, the inclined surface 28 can have a lens action and a light collecting action, and the light receiving element 26 can be obtained with low loss without using a separate lens or the like. An optical signal can be incident on the.
[0027]
In the present embodiment, the case where the light emitting element 25 is provided facing the end face 23a of the optical waveguide 23 is shown. However, instead of the light emitting element, an optical fiber that propagates a transmission signal from the transmitter is connected. Also good.
[0028]
3, if a light receiving element is arranged instead of the light emitting element 25, the wavelength multiplexed optical signal transmitted from the optical fiber 27 (41) is demultiplexed into two wavelength regions by the filter 24, An optical signal in one wavelength region (filter reflection wavelength region) is incident on the light receiving element on the end face of the optical waveguide 23, and an optical signal in the other wavelength region (filter transmission wavelength region) is incident on the light receiving element 26 on the filter 24. be able to.
[0029]
In addition, as shown in FIG. 4, if a light emitting element 25 is provided facing the end face 23a of the optical waveguide 23 and the light emitting element 25a is disposed on the filter 24, the optical signals emitted from both the light emitting elements 25 and 25a. A wavelength multiplexed signal obtained by combining Y1 and Y2 can be sent to the optical fiber 27.
[0030]
(Second Embodiment)
FIG. 5 is a sectional view showing a schematic configuration of an optical multiplexer / demultiplexer 31 according to the second embodiment of the present invention. In this optical multiplexer / demultiplexer 31, two clad substrates 32 and 34 are bonded together with a filter 38 interposed therebetween. The lower clad substrate 32 is a resin substrate made by duplication, for example, injection molding, and a linear groove formed on the upper surface of the clad substrate 32 is filled with a core material to form an optical waveguide 33. Both end faces of the optical waveguide 33 are exposed on the outer peripheral surface of the clad substrate 32. A part of the bottom surface of the optical waveguide 33 (or the bottom surface of the groove) protrudes inward or upward so as to substantially block the optical waveguide 33, and inclined surfaces 36 are formed on both surfaces thereof. Both inclined surfaces 36 have a symmetrical shape in the cross section shown in FIG. In addition, the inclined surface 36 may be a flat surface, but in this embodiment, the inclined surface 36 is curved in a concave cross section.
[0031]
The upper clad substrate 34 is also a resin substrate made by duplication, for example, injection molding, and the optical waveguide 35 is formed by filling the core material in the groove formed on the lower surface of the clad substrate 34. One end surface 35a of the optical waveguide 35 is exposed on the outer peripheral end surface of the clad substrate 34, and the other end portion of the optical waveguide 35 is disposed so as to cover the region of the inclined surface 36 formed in the lower clad substrate 32. An inclined surface 37 is also formed at the other end of the optical waveguide 35. The inclined surface 37 may also be a flat surface, but is curved in a concave cross section in this embodiment.
[0032]
The filter 38 sandwiched between the upper and lower clad substrates 34 and 32 allows only an optical signal in a predetermined wavelength range to pass therethrough and needs to be provided at least in a region where both the optical waveguides 35 and 33 overlap. Considering the manufacturing process and the like, it is preferable to provide the entire bonding region of the clad substrates 34 and 32.
[0033]
FIG. 5 shows an example in which the optical multiplexer / demultiplexer 31 is used as an optical transceiver. That is, the end surface 33 a of the optical waveguide 33 is opposed to the light emitting element 40 realized by a semiconductor laser, a light emitting diode, or the like so as to be optically connected to the one end surface 33 a of the optical waveguide 33. An optical fiber 41 serving as a transmission path for transmission / reception signals is opposed to 33b so as to be optically connected to the other end face 33b of the optical waveguide 33. In addition, a light receiving element 39 realized by a photodiode, a phototransistor, or the like is opposed to the end face 35 a of the optical waveguide 35.
[0034]
Next, the optical transceiver operation of the optical multiplexer / demultiplexer 31 will be described. A transmission signal emitted from the light emitting element 40 and incident on the optical waveguide 33 is an optical signal in a wavelength region that does not pass through the filter 38. Therefore, when a transmission signal is emitted from the light emitting element 40, the transmission signal propagates through the optical waveguide 33 as indicated by a broken line arrow Y1. At this time, the transmission signal that hits the inclined surface 36 is totally reflected by the inclined surface 36 and enters the filter 24, but the transmission signal is reflected by the filter 38 and returns to the optical waveguide 33 again, and is totally reflected by the other inclined surface 36. Then, it propagates again through the optical waveguide 33 and enters the optical fiber 41.
[0035]
Further, the received signal transmitted through the optical fiber 41 is an optical signal in a wavelength region that passes through the filter 38. Therefore, the received signal transmitted from the optical fiber 41 enters the optical waveguide 33 and propagates in the optical waveguide 33. The received signal propagating in the optical waveguide 33 strikes the inclined surface 36 and is totally reflected, enters the filter 38, passes through the filter 38, and enters the optical waveguide 35. The received signal that has entered the optical waveguide 35 is reflected by the inclined surface 37 and bent in the propagation direction, propagates through the optical waveguide 35, and is received by the light receiving element 39.
[0036]
Also in this optical multiplexer / demultiplexer 31, the side on which the light is reflected by the filter 38 can be formed by one optical waveguide 33, in particular, a linear optical waveguide, so the optical multiplexer / demultiplexer 31 can be downsized. be able to. In particular, since the light emitting element 40 and the light receiving element 39 can be arranged close to each other and can be arranged in the substrate thickness direction, the optical multiplexer / demultiplexer 31 can be made extremely small. Further, according to the optical multiplexer / demultiplexer 31 of the present invention, since it is not necessary to bend the optical waveguides 33 and 35, there is no light propagation loss due to the bending of the optical waveguide, and the optical propagation loss as a whole is reduced. Can be reduced. Furthermore, in this embodiment, since the inclined surface 36 is curved in a concave shape, the inclined surface 36 can have a lens action and a light collecting action, and an optical signal can be sent to the light receiving element without using a separate lens or the like. It can be made incident.
[0037]
In the present embodiment, the case where the light emitting element 40 is provided facing the end face 33a of the optical waveguide 33 is shown. However, instead of the light emitting element, an optical fiber that propagates a transmission signal from the transmitter is connected. Also good.
[0038]
In the configuration of FIG. 5, if a light receiving element is arranged instead of the light emitting element 40, the wavelength multiplexed optical signal transmitted from the optical fiber 27 (41) is demultiplexed into two wavelength regions by the filter 38. An optical signal in one wavelength region (filter reflection wavelength region) is incident on the light receiving element on the end surface of the optical waveguide 33, and an optical signal in the other wavelength region (filter transmission wavelength region) is incident on the light receiving element 39 on the end surface of the optical waveguide 35. be able to.
[0039]
Although not shown, if a light emitting element is provided facing the end face of the optical waveguide 33 and a light emitting element is also disposed on the filter 38, as in the case of the first embodiment, the light is emitted from both light emitting elements. The wavelength multiplexed signal obtained by combining the optical signals can be sent to the optical fiber.
[0040]
(Third embodiment)
FIG. 6 is a cross-sectional view showing a schematic configuration of an optical multiplexer / demultiplexer 51 according to the third embodiment of the present invention. In this optical multiplexer / demultiplexer 51, two clad substrates 54 and 52 are bonded together by an adhesive 56. The lower clad substrate 54 is a resin substrate made by duplication, for example, injection molding, and a linear groove formed on the upper surface of the clad substrate 54 is filled with a core material to form an optical waveguide 55. ing. One end of the optical waveguide 55 is linearly formed with a constant cross-sectional area, and its end surface 55a is exposed in a relatively large area on the outer peripheral surface of the clad substrate 54. Further, at the other end portion of the optical waveguide 55, a part of the bottom surface of the optical waveguide 55 (or the bottom surface of the groove) protrudes inward or upward so as to block the optical waveguide 55, and an inclined surface 58 is formed. ing. The inclined surface 58 may be a flat surface, but is curved in a concave cross section in this embodiment. As a result, the end surface of the optical waveguide 55 is exposed to the outer peripheral surface of the clad substrate 54 at a relatively small area at this location.
[0041]
The upper clad substrate 52 has the same structure as the lower clad substrate 54. That is, the upper clad substrate 52 is a resin substrate made by replication, for example, injection molding, and a linear groove formed on the lower surface of the clad substrate 52 is filled with a core material to form an optical waveguide 53. Is formed. One end of the optical waveguide 53 is linearly formed with a constant cross-sectional area, and its end surface 53 a is exposed in a relatively large area on the outer peripheral surface of the clad substrate 52. Further, at the other end of the optical waveguide 53, a part of the top surface (or the upper surface of the groove) of the optical waveguide 53 protrudes inward or downward so as to block the optical waveguide 55, thereby forming an inclined surface 57. Has been. The inclined surface 57 may be a flat surface, but in this embodiment, the inclined surface 57 is curved in a concave shape in cross section. As a result, the end face of the optical waveguide 53 is exposed to the outer peripheral surface of the clad substrate 52 with a relatively small area at this location.
[0042]
The upper and lower clad substrates 52 and the clad substrate 54 are bonded with an adhesive 56 interposed therebetween, and the upper and lower optical waveguides 53 and 55 are overlapped with each other. A filter 59 that allows only optical signals in a predetermined wavelength range to pass through the outer peripheral surfaces of the substrates 52 and 54 so as to face the end surfaces of the optical waveguides 53 and 55 on the side where the inclined surfaces 57 and 58 are formed. It is glued. Here, although the optical waveguides 53 and 55 are adjacent to each other, a layer of an adhesive 56 exists between the optical waveguides 53 and 55 and acts as a clad layer, so that the optical waveguides 53 and 55 are propagated. However, the light propagating in the optical waveguide 55 does not leak into the optical waveguide 53.
[0043]
FIG. 6 shows an example in which the optical multiplexer / demultiplexer 51 is used for optical demultiplexing. That is, the optical fiber 60 for optical signal transmission is optically connected to the end face 53 a of the optical waveguide 53, and the optical fiber 61 for optical signal transmission is optically connected to the end face 55 a of the optical waveguide 55. The optical fiber 62 is optically connected to the other end faces of the optical waveguides 53 and 55 through the filter 59.
[0044]
Thus, in this optical multiplexer / demultiplexer 51, when an optical signal in the filter transmission wavelength region is transmitted from the optical fiber 60, this optical signal enters the optical waveguide 53 as indicated by Y1 in FIG. Then, it propagates in the optical waveguide 53. The optical signal propagated in the optical waveguide 53 is reflected by the inclined surface 57 and then emitted from the optical waveguide 53 to reach the filter 59. Since this light is light in the filter transmission wavelength region, it passes through the filter 59 and enters the optical fiber 62 and is transmitted by the optical fiber 62.
[0045]
In contrast, when an optical signal in the filter reflection wavelength region is transmitted from the optical fiber 60, this optical signal enters the optical waveguide 53 and propagates through the optical waveguide 53 as indicated by Y2 in FIG. To do. The optical signal propagating through the optical waveguide 53 is reflected by the inclined surface 57, is emitted from the optical waveguide 53 at an angle inclined toward the optical waveguide 55, and reaches the filter 59. Since this light is light in the filter reflection wavelength region, it is reflected by the filter 59, then enters the lower optical waveguide 55, propagates through the optical waveguide 55, enters the optical fiber 61, and is transmitted by the optical fiber 61. The
[0046]
Also in this optical multiplexer / demultiplexer 51, since the optical waveguides 53 and 55 can be formed by linear optical waveguides, the optical multiplexer / demultiplexer 51 can be miniaturized. In particular, since the optical fibers 60 and 61 can be arranged close to each other and can be arranged so as to overlap each other in the substrate thickness direction, the optical multiplexer / demultiplexer 51 can be made extremely small. Further, according to the optical multiplexer / demultiplexer 51 of the present invention, since it is not necessary to bend the optical waveguide, there is no light propagation loss due to the bending of the optical waveguide, and the light propagation loss can be reduced as a whole of the optical waveguide. . Further, in this embodiment, since the inclined surfaces 57 and 58 are curved in a concave shape, the inclined surfaces 57 and 58 can have a lens action and a light collecting action, and an optical fiber can be used without using a separate lens or the like. An optical signal can be incident on 62 or the like.
[0047]
In this embodiment as well, as in the case of the first embodiment and the second embodiment, it is needless to say that the type and arrangement of optical elements can be appropriately changed and used for multiplexing.
[0048]
【The invention's effect】
In the optical multiplexer / demultiplexer of the present invention, it is not necessary to bend the optical waveguide greatly, and in the preferred embodiment, the optical waveguide can be formed in a straight line, so that the optical multiplexer / demultiplexer can be miniaturized. . Therefore, it is possible to reduce the size of the module including the optical component. In addition, since it is not necessary to bend the optical waveguide greatly, light hardly leaks from the optical waveguide, and the waveguide efficiency of the optical multiplexer / demultiplexer can be increased.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a conventional optical multiplexer / demultiplexer.
FIG. 2 is a plan view showing a schematic configuration of another conventional optical multiplexer / demultiplexer.
FIG. 3 is a cross-sectional view showing a schematic configuration of the optical multiplexer / demultiplexer according to the first embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view illustrating different usage states of the above optical multiplexer / demultiplexer.
FIG. 5 is a cross-sectional view showing a schematic configuration of an optical multiplexer / demultiplexer according to a second embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a schematic configuration of an optical multiplexer / demultiplexer according to a third embodiment of the present invention.
[Explanation of symbols]
21, 31, 51 Optical multiplexer / demultiplexer
22, 32, 52, 34, 54 Clad substrate
23, 33, 53, 35, 55 Optical waveguide
24, 38, 59 filters
28, 36, 37, 57, 58 Inclined surface
56 Adhesive layer

Claims (6)

Each groove provided in the two clad substrates is filled with a core material to form an optical waveguide, and the opposing surfaces of the optical waveguides provided in the two clad substrates are optically separated from each other. The two surfaces of the clad substrate on which the optical waveguides are formed are arranged so as to face each other, and a filter that transmits light in a predetermined wavelength region and reflects light in other wavelength regions is used as a light guide for both clad substrates. Arranged on the end face of the clad substrate facing the end face of the waveguide,
An optical multiplexer / demultiplexer for demultiplexing light propagating in the optical waveguide by the filter, or for combining light propagating in the optical waveguide and light incident on the optical waveguide from the outside,
A first reflecting surface that reflects light propagating through the optical waveguide toward the filter at an end of one of the two clad substrates;
The first reflection surface is formed by an inclined surface with respect to the optical axis direction of the optical waveguide, which protrudes inward so as to block the optical waveguide at an end portion of the optical waveguide where the filter is opposed to the optical waveguide. The end face of the optical waveguide on which the filter is arranged oppositely is thereby exposed on the outer peripheral surface of one clad substrate with a relatively small area,
Of the light reflected by the first reflecting surface, the light in the filter transmission wavelength range is transmitted through the filter and emitted to the outside.
Of the light reflected by the first reflecting surface, light in a wavelength region other than the filter transmission wavelength region is reflected by the filter and incident on the end surface of the other optical waveguide,
A second reflecting surface that reflects light propagating through the optical waveguide toward the filter at an end of the other clad substrate of the two clad substrates;
The second reflecting surface is formed by an inclined surface with respect to the optical axis direction of the optical waveguide that protrudes inward so as to block the optical waveguide at an end portion of the optical waveguide on which the filter is opposed. The end face of the optical waveguide on which the filter is arranged oppositely is thereby exposed on the outer peripheral surface of the other cladding substrate with a relatively small area,
Of the light reflected by the first reflection surface, light in a wavelength region other than the filter transmission wavelength region is reflected by the filter and incident on the end surface of the other optical waveguide. An optical multiplexer / demultiplexer that is reflected toward a direction substantially parallel to the optical axis direction of the optical waveguide.   The optical multiplexer / demultiplexer according to claim 1, wherein the first reflecting surface is formed in a curved surface shape.   2. The optical multiplexer / demultiplexer according to claim 1, wherein the second reflecting surface is formed in a curved surface shape.   The optical multiplexer / demultiplexer according to claim 1, wherein the clad substrates are bonded together by an adhesive.   The optical multiplexer / demultiplexer according to claim 1, wherein the clad substrate is made of resin. Optical communication device using an optical demultiplexer according to any one of claims 1 to 5.

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