JP2014150224A - Optical transmission module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission module capable of reducing manufacturing cost.SOLUTION: An optical transmission module 1 has a wavelength selection filter 91, the wavelength selection filter 91 being provided with an incident surface 91a, an emission surface 91b, a side surface 91c, and a side surface 91d. The side surface 91c and the side surface 91d extend from the incident surface 91a to the emission surface 91b. The side surface 91c and the side surface 91d extend along a direction of deflection of an optical signal S1a entering from the incident surface 91a and then deflected on the incident surface 91a.

Description

The present invention relates to an optical transmission module.

Patent Document 1 discloses an optical device. The optical device of Patent Document 1 includes an optical demultiplexer. The optical demultiplexer includes a housing, a collimator lens, a plurality of wavelength selection means, a plurality of condensing lenses, and a plurality of light receiving units. The housing is cylindrical. The plurality of wavelength selecting means are arranged at substantially equal intervals on the light propagation path. One surface of the wavelength selecting means is arranged toward the collimating lens side. The angle formed by this surface and the light propagation path is 45 degrees.

JP 2005-140960 A Japanese Patent Application No. 2012-121270

If the wavelength selection filter aperture is the range in which the wavelength selection filter performs its function among the incident position and incident angle of light incident on the wavelength selection filter, the aperture may be limited by the shape of the wavelength selection filter. is there. Also, in order to transmit the aperture, if the incident angle of incident light is large, the incident position is severely limited and the allowable displacement is small. Capacity increases. For example, when the shape of the wavelength selection filter viewed from above the mounting surface of the wavelength selection filter is a rectangle, and the incident surface (long side of the rectangle) of the wavelength selection filter is inclined with respect to the incident light, the wavelength selection filter The allowable range of the incident position of the incident light on the incident surface is that even if a wavelength selective filter with a large incident surface is prepared, the light travels diagonally in the wavelength selective filter, so that the incident surface can not be used effectively. However, the allowable deviation of the incident position of the incident light is small compared to the size of the incident surface and the exit surface. As the allowable range of the incident position is smaller, it becomes more difficult to secure a sufficient alignment margin for the wavelength selection filter.

In order to increase the allowable displacement of the incident light with respect to the incident surface of the wavelength selective filter when the shape of the wavelength selective filter viewed from above the mounting surface of the wavelength selective filter is rectangular, for example, when viewed from above the mounting surface. In some cases, the thickness of the wavelength selective filter is reduced (the short side of the rectangle is reduced). However, if the thickness of the wavelength selection filter is reduced, the rigidity of the wavelength selection filter decreases. Therefore, the filter glass of the main body of the wavelength selection filter is caused by the internal stress of the WDM filter (WDM: Wavelength Division Multiplexing) provided in the wavelength selection filter. May be deformed (curved), and the optical characteristics of the wavelength selective filter (particularly the optical characteristics with respect to the reflected light) will deteriorate.

In addition, when the shape of the wavelength selection filter viewed from above the mounting surface of the wavelength selection filter is rectangular, in order to increase the allowable positional deviation of incident light with respect to the incident surface of the wavelength selection filter, for example, a cube-shaped wavelength Sometimes a selection filter (PBS) is used. However, in the case of cube-shaped PBS, polishing is necessary because the triangular prism part with the dielectric multilayer film formed on the slope that forms an angle of 45 degrees with the incident surface and the separately prepared triangular prism parts are attached on the slope and assembled. The number of incident surfaces of light, the exit surface of light that needs to be polished, and the surface to which the dielectric multilayer film is formed and bonded are three or more in total, which is relatively large. Thus, when there are a relatively large number of surfaces that need to be polished, it takes time and effort. Furthermore, cube-shaped PBS has a high component unit price. Furthermore, in the case of a cube-shaped PBS, the incident surface and the exit surface are arranged perpendicular to the light traveling path, and therefore, incident light and exit light may be reflected. When a cube-shaped PBS is used, it is necessary to consider such reflected light, so that the apparatus configuration becomes complicated and the cost is increased.

Accordingly, an object of the present invention has been made in view of the above matters, and is to provide an optical transmission module capable of reducing the manufacturing cost.

An optical transmission module according to the present invention includes a light source and a wavelength selection filter, the light source and the wavelength selection filter are provided on a mounting surface of a substrate, and the light source and the wavelength selection filter are along a reference axis. The reference axis extends from the first end of the substrate to the second end in parallel to the mounting surface, and the light source emits an optical signal along the reference axis. The wavelength selection filter includes an entrance surface, an exit surface, a first side surface, and a second side surface, and the wavelength selection filter includes light having a wavelength within a preset wavelength range including the wavelength of the optical signal. And the wavelength selection filter emits the optical signal along the reference axis when receiving the optical signal from the light source, and the incident surface includes a first end and a second end. The incident surface is perpendicular to the mounting surface, and the incident surface is The incident surface is inclined from a plane perpendicular to the reference axis, the incident surface receives the optical signal, the exit surface includes a third end and a fourth end, and the exit surface is along the entrance surface. The emission surface emits the optical signal after passing through the wavelength selection filter along the reference axis, and the first side surface is formed between the first end and the third end. The second side surface extends between the second end and the fourth end, and the first side surface and the second side surface are both reference Extending along a surface, the reference surface is perpendicular to the mounting surface, the reference surface extends along a refraction direction of the optical signal incident on the incident surface, and the optical signal is transmitted from the light source to the After entering the entrance surface, the light passes through the wavelength selection filter and exits from the exit surface along the reference axis.

According to the present invention, since the first side surface and the second side surface 91d extend along the refraction direction of the optical signal incident on the incident surface, the side surface extends perpendicularly to the incident surface as in the prior art. The aperture of the wavelength selective filter is wider than in the case where In other words, the shape of the wavelength selection filter necessary for realizing a certain aperture, specifically, the area of the surface of the wavelength selection filter viewed from above the mounting surface, the side surface is the entrance surface as in the past. Compared to the case of extending vertically, it is reduced. Therefore, if the wavelength selection filter is used, the shape of the wavelength selection filter can be made compact, so that a mounting surface having a limited area can be used effectively. Further, if a wavelength selective filter having a compact shape as compared with the conventional one is used, the operation of arranging the wavelength selective filter on the mounting surface becomes easy, and thus the manufacturing cost of the optical transmission module can be reduced. In addition, since the aperture does not depend on the thickness of the wavelength selection filter along the reference axis (interval between the entrance surface and the exit surface), so that the rigidity of the wavelength selection filter can be sufficiently secured while ensuring a certain aperture, The wavelength selective filter can have a thickness along the reference axis. Also, in the case of wavelength selective filters, the two surfaces that need to be polished are the incident surface and the output surface, so it is more time-consuming to implement than the conventional cube-shaped PBS that requires three or more surfaces to be polished. Therefore, the manufacturing cost of the optical transmission module can be reduced.

In the present invention, when the incident angle of the optical signal with respect to the incident surface is larger than the refraction angle of the optical signal on the incident surface, the reference surface is the difference between the incident angle and the refraction angle. It extends from the entrance surface toward the exit surface so as to incline from the axis. Therefore, the inclination of the side surface can be defined by the incident angle and the refraction angle of the optical signal.

In the present invention, comprising a plurality of optical elements including the wavelength selection filter, the plurality of optical elements are provided on the mounting surface, the mounting surface is provided with a plurality of grooves, each of the plurality of grooves Is substantially in contact with any one of the plurality of optical elements. As described above, since the groove is provided on the mounting surface so as to be substantially in contact with the optical element, when the optical element is fixed to the mounting surface using a resin, excess resin flows into the groove, so that the excess resin is optical. It is possible to avoid flowing into the element.

ADVANTAGE OF THE INVENTION According to this invention, the optical transmission module which can reduce manufacturing cost can be provided.

It is a figure which shows the structure of the optical transmission module which concerns on embodiment. It is a figure for demonstrating the structure of the wavelength selection filter which concerns on embodiment. It is a figure for demonstrating the structure of the optical subassembly which concerns on embodiment. It is a figure for demonstrating the optical characteristic of the wavelength selection filter which concerns on embodiment. It is a figure which shows the other structure of the optical transmission module which concerns on embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, if possible, the same elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is a diagram illustrating a configuration of an optical transmission module 1 according to the embodiment. The optical transmission module 1 is an optical transmission module used for wavelength division multiplexing communication. As an example, the optical transmission module 1 is a four-wave integrated optical transmission module. The optical transmission module 1 includes a package 2, a substrate 3, a circuit unit 4, a light emitting unit 5, and an optical multiplexing unit 6. The package 2 accommodates the substrate 3, the circuit unit 4, the light emitting unit 5, and the optical multiplexing unit 6 inside the package 2. The substrate 3 and the circuit unit 4 are provided along the direction of the reference axis Ax. The reference axis Ax extends parallel to the mounting surface 3a of the substrate 3. The reference axis Ax extends from the end 1a (first end) of the substrate 3 to the end 1b (second end) of the substrate 3. The light emitting part 5 and the optical multiplexing part 6 are provided on the mounting surface 3a. The light emitting part 5 and the optical multiplexing part 6 are provided along the reference axis Ax. The light emitting portion 5 is provided on the end 1 b side of the substrate 3. The optical multiplexing unit 6 is provided on the end 1 a side of the substrate 3. 1-3 and 5 describe an orthogonal coordinate system OS having an x-axis, a y-axis, and a z-axis. The reference axis Ax is parallel to the x axis. The mounting surface 3a extends along the xy plane. The light sources 71 to 74, the light reflection plate 8, the wavelength selection filters 91 and 92, the polarization rotation component 10, and the optical subassembly 11 are directed toward the z-axis direction (the normal direction of the mounting surface 3a) on the mounting surface 3a. It is set up.

The light emitting unit 5 includes light sources 71 to 74, a light reflection plate 8, wavelength selection filters 91 and 92, and a polarization rotation component 10. The light sources 71 to 74, the light reflection plate 8, the wavelength selection filters 91 and 92, and the polarization rotation component 10 are provided on the mounting surface 3a. Each of the light sources 71 to 74, the light reflection plate 8, the wavelength selection filters 91 and 92, and the polarization rotation component 10 is an optical element. The light sources 71 to 74 are provided on the end portion 1 b side (circuit portion 4 side) of the substrate 3. The polarization rotating component 10 is provided on the end 1a side (the optical multiplexing unit 6 side) of the substrate 3. The light reflection plate 8 and the wavelength selection filters 91 and 92 are provided between the light sources 71 to 74 and the polarization rotation component 10. The optical multiplexing unit 6 includes an optical subassembly 11. The optical subassembly 11 is provided on the mounting surface 3a. The optical subassembly 11 is an optical element. The optical subassembly 11 is provided between the polarization rotation component 10 and the sleeve 12.

The light source 71 includes a light source device 71a and an optical lens 71b. The light source 71 emits an optical signal S1a along the reference axis Ax (to the optical path L1a). The light source device 71a is, for example, a semiconductor laser. The light source device 71a outputs a p-polarized optical signal. The optical signal emitted from the light source device 71a has, for example, a center wavelength of 1295.56 nm (hereinafter referred to as wavelength λ1). The light source device 71 a is electrically connected to the circuit unit 4. The light source device 71 a outputs an optical signal in accordance with the electrical signal from the circuit unit 4. The optical lens 71b is a collimator and a lens. The optical lens 71b collimates the optical signal output from the light source device 71a and emits it as an optical signal S1a to the optical path L1a. The optical path L1a extends along the reference axis Ax. The optical signal S1a is p-polarized light. The center wavelength of the optical signal S1a is the wavelength λ1.

The light source 72 includes a light source device 72a and an optical lens 72b. The light source 72 emits an optical signal S2a along the reference axis Ax (to the optical path L2a). The light source device 72a is, for example, a semiconductor laser. The light source device 72a outputs a p-polarized optical signal. The optical signal emitted from the light source device 72a has, for example, a central wavelength of 1300.05 nm (hereinafter referred to as wavelength λ2). The light source device 72 a is electrically connected to the circuit unit 4. The light source device 72 a outputs an optical signal in accordance with the electrical signal from the circuit unit 4. The optical lens 72b is a collimator and a lens. The optical lens 72b collimates the optical signal output from the light source device 72a, and emits it to the optical path L2a as the optical signal S2a. The optical path L2a extends along the reference axis Ax. The optical signal S2a is p-polarized light. The center wavelength of the optical signal S2a is the wavelength λ2.

The light source 73 includes a light source device 73a and an optical lens 73b. The light source 73 emits an optical signal S3a along the reference axis Ax (to the optical path L3a). The light source device 73a is, for example, a semiconductor laser. The light source device 73a outputs a p-polarized optical signal. The optical signal emitted from the light source device 73a has, for example, a central wavelength of 1304.58 nm (hereinafter referred to as wavelength λ3). The light source device 73 a is electrically connected to the circuit unit 4. The light source device 73a outputs an optical signal in accordance with the electrical signal from the circuit unit 4. The optical lens 73b is a collimator and a lens. The optical lens 73b collimates the optical signal output from the light source device 73a and emits it as an optical signal S3a to the optical path L3a. The optical path L3a extends along the reference axis Ax. The optical signal S3a is p-polarized light. The center wavelength of the optical signal S3a is the wavelength λ3.

The light source 74 includes a light source device 74a and an optical lens 74b. The light source 74 emits an optical signal S4a along the reference axis Ax (to the optical path L4a). The light source device 74a is, for example, a semiconductor laser. The light source device 74a outputs a p-polarized optical signal. The optical signal emitted from the light source device 74a has a center wavelength of 1309.14 nm (hereinafter referred to as wavelength λ4), for example. The light source device 74 a is electrically connected to the circuit unit 4. The light source device 74 a outputs an optical signal in accordance with the electrical signal from the circuit unit 4. The optical lens 74b is a collimating lens. The optical lens 74b collimates the optical signal output from the light source device 74a, and emits it as an optical signal S4a to the optical path L4a. The optical path L4a extends along the reference axis Ax. The optical signal S4a is p-polarized light. The center wavelength of the optical signal S4a is the wavelength λ4.

The wavelength selection filter 91 is provided on the optical path L1a. The light source 71 and the wavelength selection filter 91 are provided along the reference axis Ax (on the optical path L1a). The wavelength selection filter 91 includes an incident surface 91a, an emission surface 91b, a side surface 91c, a side surface 91d, a filter glass 911, and a WDM filter 912. The wavelength selection filter 91 includes light having a wavelength within a preset wavelength range including the wavelength of the optical signal S1a (that is, the wavelength λ2 of the optical signal S2a, the wavelength λ3 of the optical signal S3a, the wavelength λ3 of the optical signal S3a, and the light The light having a wavelength in a wavelength range not including the wavelength λ4 of the signal S4a is transmitted (see the part (A) in FIG. 4). When receiving the optical signal S1a from the light source 71, the wavelength selection filter 91 transmits the optical signal S1a and emits the optical signal S1a along the reference axis Ax (to the optical path L1b) from the emission surface 91b. The optical path L1b extends along the reference axis Ax. The incident surface 91a is the surface of the filter glass 911. The incident surface 91a receives the optical signal S1a. The optical signal S1a enters the wavelength selection filter 91 from the optical path L1a through the incident surface 91a. The emission surface 91b is a surface of the WDM filter 912. The optical signal S1a passes through the filter glass 911 and the WDM filter 912, and is emitted from the emission surface 91b to the optical path L1b. The filter glass 911 is provided on the incident surface 91a side, and the WDM filter 912 is provided on the emission surface 91b side. The wavelength selection filter 91 reflects the optical signal S3a incident on the emission surface 91b from the optical path L3b toward the optical path L1b on the emission surface 91b. The optical signal S1b is emitted from the wavelength selection filter 91 to the optical path L1b through the emission surface 91b. The optical signal S1b is a combination of the optical signal S1a that has passed through the wavelength selection filter 91 and the optical signal S3a that has been reflected from the exit surface 91b. The optical signal S1b is p-polarized light.

The wavelength selection filter 92 is provided on the optical path L2a. The light source 72 and the wavelength selection filter 92 are provided along the reference axis Ax (on the optical path L2a). The wavelength selection filter 92 includes an incident surface 92a, an output surface 92b, a side surface 92c, a side surface 92d, a filter glass 921, and a WDM filter 922. The wavelength selection filter 92 includes light having a wavelength within a preset wavelength range including the wavelength of the optical signal S2a (that is, the wavelength λ3 of the optical signal S3a including the wavelength λ1 of the optical signal S1a and the wavelength λ2 of the optical signal S2a). Transmits light having a wavelength in a wavelength range that does not include the wavelength λ4 of the optical signal S4a (see part (B) of FIG. 4). When receiving the optical signal S2a from the light source 72, the wavelength selection filter 92 transmits the optical signal S2a and emits the optical signal S2a from the emission surface 92b along the reference axis Ax (to the optical path L2b). The optical path L2b extends along the reference axis Ax. The incident surface 92a is the surface of the filter glass 921. The incident surface 92a receives the optical signal S2a. The optical signal S2a enters the wavelength selection filter 92 from the optical path L2a through the incident surface 92a. The exit surface 92b is the surface of the WDM filter 922. The optical signal S2a passes through the filter glass 921 and the WDM filter 922, and is emitted from the emission surface 92b to the optical path L2b. The filter glass 921 is provided on the incident surface 92a side, and the WDM filter 922 is provided on the emission surface 92b side. The wavelength selection filter 92 reflects the optical signal S4a incident on the emission surface 92b from the optical path L4b toward the optical path L2b on the emission surface 92b. The optical signal S2b is emitted from the wavelength selection filter 92 to the optical path L2b through the emission surface 92b. The optical signal S2b is a combination of the optical signal S2a that has passed through the wavelength selection filter 92 and the optical signal S4a that has been reflected from the emission surface 92b. The optical signal S2b is p-polarized light.

The configuration of the wavelength selection filter 91 will be described in detail with reference to FIG. The wavelength selection filter 92 has the same configuration as the wavelength selection filter 91 except for the optical characteristics shown in the part (A) of FIG. 4 and the part (B) of FIG.

The wavelength selection filter 91 includes an incident surface 91a, an emission surface 91b, a side surface 91c (first side surface), and a side surface 91d (second side surface). The incident surface 91a includes an end 91a1 (first end) and an end 91a2 (second end). The incident surface 91a is perpendicular to the mounting surface 3a. The incident surface 91a is inclined from the reference surface SF2 perpendicular to the reference axis Ax. The incident surface 91a receives the optical signal S1a. The emission surface 91b includes an end 91b1 (third end) and an end 91b2 (fourth end). The exit surface 91b extends along the entrance surface 91a. The emission surface 91b emits the optical signal S1a that has passed through the wavelength selection filter 91 along the reference axis Ax (to the optical path L1b). The optical signal S1a is incident on the incident surface 91a from the light source 71, passes through the wavelength selection filter 91, and is emitted from the emission surface 91b along the reference axis Ax (to the optical path L1b). The optical signal S1b shown in FIGS. 1 and 2 is emitted from the emission surface 91b. The optical signal S1b is a combination of the optical signal S1a after passing through the wavelength selection filter 91 and the optical signal S3a reflected by the exit surface 91b.

The side surface 91c extends between the end 91a1 and the end 91b1. The side surface 91d extends between the end 91a2 and the end 91b2. Both the side surface 91c and the side surface 91d extend along the reference surface SF1. The reference surface SF1 is perpendicular to the mounting surface 3a. The reference surface SF1 extends along the optical path L1ab. The optical path L1ab is an optical path that travels through the filter glass 911 after the optical signal S1a incident on the incident surface 91a is refracted on the incident surface 91a. The optical path L1ab corresponds to the refraction direction of the optical signal S1a on the incident surface 91a.

For example, when the incident angle α of the optical signal S1a with respect to the incident surface 91a is larger than the refraction angle β of the optical signal S1a on the incident surface 91a, the reference surface SF1 has an inclination angle γ (γ = Α−β) and extends from the incident surface 91a toward the exit surface 91b so as to be inclined from the reference axis Ax. The incident angle α is an angle (acute angle) between the optical path L1a and the normal line Nx. The refraction angle β is an angle (acute angle) between the optical path L1ab and the normal line Nx.

When the wavelength selection filter 91 is used, the side surface 91c and the side surface 91d extend along the refraction direction of the optical signal S1a incident on the incident surface 91a, so that the side surface extends perpendicularly to the incident surface as in the prior art. Compared with the case where the aperture Ap is larger. In other words, the shape of the wavelength selection filter 91 necessary for realizing a certain aperture Ap, specifically, the area of the surface of the wavelength selection filter 91 viewed from above the mounting surface 3a is the side surface as in the past. Is reduced as compared with the case where the film extends perpendicularly to the incident surface. Therefore, if the wavelength selection filter 91 is used, the shape of the wavelength selection filter can be made compact, so that the mounting surface 3a having a limited area can be used effectively. Further, if the wavelength selective filter 91 having a compact shape as compared with the conventional one is used, the operation of arranging the wavelength selective filter 91 on the mounting surface 3a becomes easy, and thus the manufacturing cost of the optical transmission module 1 can be reduced. Further, since the aperture Ap does not depend on the thickness of the wavelength selection filter 91 along the reference axis Ax (the distance between the incident surface 91a and the emission surface 91b), the rigidity of the wavelength selection filter 91 is also secured while ensuring a certain aperture Ap. The wavelength selection filter 91 can have a thickness along the reference axis Ax so that it can be sufficiently secured. Further, in the case of the wavelength selective filter 91, the surfaces that need to be polished are two surfaces, that is, the incident surface 91a and the output surface 91b. Therefore, compared to the conventional cube-shaped PBS that requires polishing on three or more surfaces. Therefore, it is possible to reduce the manufacturing cost of the optical transmission module 1. Since the wavelength selection filter 92 also has the same configuration as the wavelength selection filter 91, the same effect as the wavelength selection filter 91 is achieved. Further, the inclination of the side surface 91c and the inclination of the side surface 91d can be defined by the inclination angle γ of the difference between the incident angle α of the optical signal S1a with respect to the incident surface 91a and the refraction angle β of the optical signal S1a on the incident surface 91a. Further, the incident surface 91a and the exit surface 91b of the wavelength selection filter 91, the entrance surface 92a and the exit surface 92b of the wavelength selection filter 92, the reflection surface 8a of the light reflecting plate 8, the entrance surface 111 of the optical subassembly 11, and the exit. The surface 112 extends along the same direction. Thus, since the light reflection plate 8, the wavelength selection filter 91, the wavelength selection filter 92, and the optical subassembly 11 are arranged on the mounting surface 3a so as to extend in the same direction, the light reflection plate 8, the wavelength selection filter, and so on. 91, the wavelength selection filter 92, and the optical subassembly 11 can be easily mounted on the mounting surface 3a.

Returning to FIG. The light reflecting plate 8 is provided on the optical path L3a. The light reflecting plate 8 is provided on the optical path L4a. The light reflecting plate 8 changes the optical path L3a to the optical path L3b on the reflecting surface 8a. The light reflecting plate 8 changes the optical path L4a to the optical path L4b on the reflecting surface 8a. The light reflection plate 8 includes, for example, a metal mirror or a dielectric multilayer mirror provided on glass. The optical path L3b is orthogonal to the optical path L3a. The optical path L4b is orthogonal to the optical path L4b. The optical path L3b intersects the emission surface 91b of the wavelength selection filter 91. The optical path L4b intersects the emission surface 92b of the wavelength selection filter 92.

The polarization rotation component 10 is a half-wave plate. The polarization rotating component 10 has a configuration in which a birefringent polymer is sandwiched between glass plates, or a configuration in which crystal plates are bonded together. The polarization plane of the light that has passed through the polarization rotating component 10 is rotated by 90 degrees. That is, p-polarized light passes through the polarization rotation component 10 and is converted to s-polarized light. The polarization rotation component 10 is provided on the optical path L2b. When the polarization rotation component 10 receives the p-polarized optical signal S2b from the optical path L2b, the polarization-rotating component 10 converts the p-polarized optical signal S2b into an s-polarized optical signal S2c, and emits the optical signal S2c to the optical path L2c. The optical path L2c extends along the reference axis Ax.

The optical subassembly 11 is provided on the optical path L1b. The optical subassembly 11 is provided on the optical path L2c. When receiving the optical signal S1b from the optical path L1b and the optical signal S2c from the optical path L2c, the optical subassembly 11 emits the optical signal S5 from the emission surface 112 to the optical path L5. The optical signal S5 is a combination of the optical signal S1b and the optical signal S2c. The optical path L5 extends along the reference axis Ax. The optical path L5 extends from the emission surface 112 of the optical subassembly 11 to the optical fiber F connected to the sleeve 12 through the sleeve 12 connected to the package 2.

The configuration of the optical subassembly 11 will be described in detail with reference to FIG. The optical subassembly 11 includes a glass block 11a, a wavelength selection filter 11b, and a light reflection film 11c. The glass block 11 a includes an entrance surface 111 and an exit surface 112. The exit surface 112 is on the opposite side of the entrance surface 111 and is orthogonal to the mounting surface 3a. The wavelength selection filter 11b is provided on the incident surface 111. The wavelength selection filter 11b covers a part (for example, 1/2) of the incident surface 111. The optical path L1b intersects the incident surface 111 via the wavelength selection filter 11b. The optical path L2c directly intersects the incident surface 111. The light reflecting film 11 c is provided on the emission surface 112. The light reflecting film 11c covers a part (for example, 1/2) of the emission surface 112. The optical path L5 directly intersects the exit surface 112. The glass block 11a is made of, for example, an optically transparent glass member having a rectangular parallelepiped outer shape. The wavelength selection filter 11b transmits p-polarized light and blocks s-polarized light (see the part (C) in FIG. 4). The light reflecting film 11c reflects the optical signal S2c.

An example of a method for manufacturing the optical subassembly 11 will be described. First, a rectangular parallelepiped laminated glass block 11a is prepared. Next, a wavelength selection filter (corresponding to the wavelength selection filter 11b) is formed on the entire entrance surface 111 of the glass block 11a. Next, a light reflecting film (corresponding to the light reflecting film 11c) is formed on the entire exit surface 112 of the glass block 11a. Next, the wavelength selection filter covering the region intersecting the optical path L2c on the incident surface 111 of the glass block 11a is removed by polishing or the like to expose a part of the incident surface 111 (region intersecting the optical path L2c) of the glass block 11a. Let By this polishing, the wavelength selection filter 11b is finally formed. Next, the light reflecting film covering the region intersecting the optical path L5 is removed by polishing or the like on the exit surface 112 of the glass block 11a, and a part of the exit surface 112 (region intersecting the optical path L5) is exposed. Let By this polishing, the light reflecting film 11c is finally formed. In this way, the optical subassembly 11 is manufactured. The optical subassembly 11 may have a configuration in which a glass block 11a having a rectangular parallelepiped shape, a wavelength selection filter 11b, and a light reflection film 11c are integrally formed.

The sleeve 12 is connected to the package 2 so as to be positioned on the optical path L5. The optical path L5 reaches the optical fiber F connected to the sleeve 12 via the sleeve 12. The sleeve 12 includes an isolator 12a, an optical lens 12b, and a ferrule 12c. The isolator 12a is a polarization-independent isolator that does not depend on the plane of polarization. The isolator 12a, the optical lens 12b, and the ferrule 12c are located on the optical path L5. The optical signal S5 emitted from the emission surface 112 of the optical subassembly 11 passes through the isolator 12a, the optical lens 12b, and the ferrule 12c along the optical path L5 and reaches the optical fiber F.

FIG. 5 shows a modification of the optical transmission module 1. In the optical transmission module 1_1 illustrated in FIG. 5, grooves M1 to M3 are added to the optical transmission module 1. The optical transmission module 1_1 is the same as the optical transmission module 1 except for the grooves M1 to M3. The grooves M1 to M3 are provided on the mounting surface 3a. The mounting surface 3a can include grooves M1 to M3. The groove M <b> 1 is substantially in contact with the wavelength selection filter 91 and the wavelength selection filter 92. The groove M <b> 2 is substantially in contact with the polarization rotating component 10 and the light reflecting plate 8. The groove M3 is substantially in contact with the optical subassembly 11 and the polarization rotating component 10.

In the case of the optical transmission module 1_1, the grooves M1 to M3 are substantially in contact with each of a plurality of optical elements such as the light reflection plate 8, the wavelength selection filter 91, the wavelength selection filter 92, the polarization rotation component 10, and the optical subassembly 11. Since each is provided on the mounting surface 3a, each of the light reflecting plate 8, the wavelength selection filter 91, the wavelength selection filter 92, the polarization rotating component 10, and the optical subassembly 11 is mounted on the mounting surface 3a using resin. In the case of fixing, surplus resin flows into each of the grooves M1 to M3, so that the surplus resin flows in the light reflection plate 8, the wavelength selection filter 91, the wavelength selection filter 92, the polarization rotation component 10, and the optical subassembly 11. , Etc., can be avoided.

The optical characteristics of the wavelength selection filter 91, the wavelength selection filter 92, and the wavelength selection filter 11b will be described. 4A is a diagram illustrating the optical characteristics of the wavelength selection filter 91. FIG. 4B is a diagram illustrating the optical characteristics of the wavelength selection filter 92. In FIG. (C) part of FIG. 4 is a figure which shows the optical characteristic of the wavelength selection filter 11b. The four bar graphs shown in each of FIGS. 4A to 4C are respectively an optical signal S1a having a wavelength λ1, an optical signal S2a having a wavelength λ2, an optical signal S3a having a wavelength λ3, and an optical signal S4a having a wavelength λ4. Each effective band is shown. A graph G1 shown in part (A) of FIG. 4 shows the transmittance. A graph G2 shown in part (B) of FIG. 4 shows the transmittance. A graph G3 shown in part (C) of FIG. 4 shows the transmittance for p-polarized light. A graph G4 shown in part (C) of FIG. 4 shows the transmittance for s-polarized light. Reference symbol D1 in the figure indicates isolation between the optical signals S1a to S4a. Reference numeral D2 in the figure indicates effective bands of the optical signal S1a having the wavelength λ1, the optical signal S2a having the wavelength λ2, the optical signal S3a having the wavelength λ3, and the optical signal S4a having the wavelength λ4.

As shown in FIG. 4A, the transmittance of the wavelength selection filter 91 is higher than that of the optical signal S1a having the wavelength λ1. The wavelength selection filter 91 includes a wavelength λ1 of the optical signal S1a, and transmits light having a wavelength in a wavelength range not including the optical signal S2a of wavelength λ2, the optical signal S3a of wavelength λ3, and the optical signal S4a of wavelength λ4.

As shown in part (B) of FIG. 4, the transmittance of the wavelength selection filter 92 is higher than the optical signal S1a having the wavelength λ1 and the optical signal S2a having the wavelength λ2. The wavelength selection filter 92 includes a wavelength λ1 of the optical signal S1a and a wavelength λ2 of the optical signal S2a, and transmits light having a wavelength in a wavelength range not including the optical signal S3a having the wavelength λ3 and the optical signal S4a having the wavelength λ4.

As shown in part (C) of FIG. 4, the wavelength selection filter 11b has a high transmittance for p-polarized light, a low transmittance for s-polarized light, and hardly transmits s-polarized light.

While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

DESCRIPTION OF SYMBOLS 1,1_1 ... Optical transmission module, 10 ... Polarization rotation component, 11 ... Optical subassembly, 111, 91a, 92a ... Incident surface, 112, 91b, 92b ... Output surface, 11a ... Glass block, 11b, 91, 92 ... Wavelength selection filter, 11c ... light reflecting film, 12 ... sleeve, 12a ... isolator, 12b ... optical lens, 12c ... ferrule, 1a, 1b ... end, 2 ... package, 3 ... substrate, 3a ... mounting surface, 4 ... circuit , 5 ... light emitting part, 6 ... optical multiplexing part, 71, 72, 73, 74 ... light source, 71a, 72a, 73a, 74a ... light source device, 71b, 72b, 73b, 74b ... optical lens, 8 ... light reflection Plate, 8a ... reflective surface, 911, 921 ... filter glass, 912, 922 ... WDM filter, 91a1, 91a2, 91b1, 91b2, 92a1, 92a2, 92 1, 92b2 ... end, 91c, 91d, 92c, 92d ... side, Ap ... aperture, Ax ... reference axis, F ... optical fiber, G1, G2, G3, G4 ... graph, L1a, L1ab, L1b, L2a, L2b, L2c, L3a, L3b, L4a, L4b, L5 ... optical path, M1, M2, M3 ... groove, Nx ... normal, OS ... orthogonal coordinate system, S1a, S1b, S2a, S2b, S2c, S3a, S4a, S5 ... light Signal, SF1, SF2 ... reference plane.

Claims (3)

A light source and a wavelength selection filter;
The light source and the wavelength selection filter are provided on a mounting surface of a substrate,
The light source and the wavelength selection filter are provided along a reference axis,
The reference axis extends in parallel to the mounting surface from the first end of the substrate to the second end,
The light source emits an optical signal along the reference axis;
The wavelength selective filter includes an entrance surface, an exit surface, a first side surface, and a second side surface,
The wavelength selective filter transmits light having a wavelength in a preset wavelength range including the wavelength of the optical signal,
The wavelength selection filter, when receiving the optical signal from the light source, emits the optical signal along the reference axis,
The incident surface includes a first end and a second end;
The incident surface is perpendicular to the mounting surface;
The incident surface is inclined from a plane perpendicular to the reference axis;
The incident surface receives the optical signal,
The exit surface includes a third end and a fourth end,
The exit surface extends along the entrance surface;
The emission surface emits the optical signal after passing through the wavelength selection filter along the reference axis,
The first side surface extends between the first end and the third end;
The second side surface extends between the second end and the fourth end;
The first side surface and the second side surface both extend along a reference surface,
The reference surface is perpendicular to the mounting surface;
The reference surface extends along a refraction direction of the optical signal incident on the incident surface,
The optical signal is incident on the incident surface from the light source, passes through the wavelength selection filter, and is emitted from the emission surface along the reference axis.
An optical transmitter module. The reference plane is inclined from the reference axis by a difference between the incident angle and the refraction angle when the incident angle of the optical signal with respect to the incident plane is larger than the refraction angle of the optical signal on the incident plane. Extending from the entrance surface to the exit surface,
The optical transmission module according to claim 1. A plurality of optical elements including the wavelength selective filter;
The plurality of optical elements are provided on the mounting surface,
The mounting surface is provided with a plurality of grooves,
Each of the plurality of grooves is in contact with any of the plurality of optical elements.
The optical transmission module according to claim 1, wherein the optical transmission module is an optical transmission module.

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