Optical receiver

Abstract

To provide a photoreceiver capable of reducing reflected return light.SOLUTION: A photoreceiver according to one embodiment includes: a first collimator lens that has an incident lens subjected to incidence of first collimator light with a predetermined diameter, and an outgoing lens emitting second collimator light with a diameter smaller than the predetermined diameter by receiving light entering the incident lens and spreading out from a light-concentrated focus; and a light receiving element that has a light receiving lens where the second collimator light enters and the second collimator light is emitted as converging rays, and a light receiving section for receiving the converging rays from the light receiving lens.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an optical receiver. [Background technology]

[0002] Patent Document 1 describes an optical receiving module. The optical receiving module includes a receptacle unit and a package unit. The receptacle unit has a first lens that receives light from an optical fiber. The package unit has an optical demultiplexer that receives light from the first lens, a reflector that reflects light demultiplexed by the optical demultiplexer, and a second lens that receives light reflected by the reflector. The optical receiving module further includes a light receiving element that receives light focused by the second lens.

[0003] Patent Document 2 describes an optical receiving module and a manufacturing method thereof. The optical receiving module has a package section in which an optical demultiplexer, a reflector, a condenser lens, and a light receiving element are arranged. Light demultiplexed by the optical demultiplexer is incident on the reflector and reflected by the reflector. The light reflected by the reflector is condensed by the condenser lens and incident on the light receiving element.

[0004] Patent Document 3 describes a wavelength-multiplexed optical receiver module. The wavelength-multiplexed optical receiver module includes a collimating lens that converts input light into collimated light, a wavelength division filter that splits the collimated light into multiple signal lights based on wavelengths, and a mirror that reflects the split signal lights. The wavelength-multiplexed optical receiver module also includes a lens array having a condenser lens that condenses the signal lights reflected by the mirror, and a PD (Photo Diode) that receives the condensed signal lights. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-125045 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-137476 [Patent Document 3] Japanese Patent Application Publication No. 2017-32731 Summary of the Invention [Problem to be solved by the invention]

[0006] In the optical receiver module described above, light passing through an optical receptacle that connects to an optical fiber is converted into collimated light by a collimating lens, and then separated into signal light of each wavelength by an optical demultiplexer that has optical filters and mirrors corresponding to each wavelength. Each separated signal light is reflected by a mirror, then focused by a lens array, and reaches a light receiving element.

[0007] In order to achieve the desired photoelectric conversion characteristics in a photodetector, it is necessary to precisely position each component and achieve low-loss optical coupling to the photodetector. However, simply precisely positioning each component can result in the amount of reflected light from the lens on the surface of the photodetector exceeding a predetermined level. Therefore, it is necessary to reduce the amount of reflected light while maintaining the photodetector's sensitivity.

[0008] An object of the present disclosure is to provide an optical receiver capable of reducing reflected back light. [Means for solving the problem]

[0009] The optical receiver of the present disclosure comprises a first collimating lens having an entrance lens into which first collimated light having a predetermined diameter is incident, and an exit lens that receives light that is incident on the entrance lens and spreads from the focused focal point and emits second collimated light having a diameter smaller than the predetermined diameter, a light receiving lens into which the second collimated light is incident and that emits the second collimated light as focused light, and a light receiving element having a light receiving unit that receives the focused light from the light receiving lens. [Effects of the Invention]

[0010] According to the present disclosure, reflected back light can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing the internal structure of the optical receiver according to the embodiment. [Figure 2] 2 is a diagram showing a first collimating lens and a light receiving element of the optical receiver of FIG. 1. FIG. [Figure 3] FIG. 3 is a diagram showing a first collimator lens in FIG. 2. [Figure 4] 3 is a diagram showing an output lens of the first collimator lens and a light receiving lens of the light receiving element in FIG. 2. FIG. [Figure 5] FIG. 10 is a diagram showing a first collimator lens of an optical receiver according to a first modified example. [Figure 6] FIG. 10 is a diagram illustrating an optical receiver according to a second modification. [Figure 7] FIG. 10 is a diagram illustrating an optical receiver according to a third modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Description of the embodiments of the present disclosure] First, the details of embodiments of an optical receiver according to the present disclosure will be listed and described. (1) An optical receiver according to one embodiment includes a first collimating lens having an entrance lens onto which a first collimated light beam having a predetermined diameter is incident, and an exit lens that receives light that is incident on the entrance lens and focused and spreads from a focal point and emits a second collimated light beam having a diameter smaller than the predetermined diameter, a light-receiving lens that receives the second collimated light beam and emits the second collimated light beam as focused light, and a light-receiving element that includes a light-receiving unit that receives the focused light from the light-receiving lens.

[0013] This optical receiver includes a first collimating lens having an input lens and an output lens, and a light-receiving element having a light-receiving lens and a light-receiving section. The input lens converts the incident first collimated light into focused light, and the light diverging from the focus of the focused light is converted into a second collimated light by the output lens. The diameter of the second collimated light is smaller than that of the first collimated light. The light-receiving lens of the light-receiving element receives the second collimated light, not the focused light. Therefore, by receiving the second collimated light, which has a smaller diameter than the first collimated light, the amount of reflected light returning from the light-receiving lens can be reduced. This prevents the amount of reflected light returning from the light-receiving lens, which is the surface of the light-receiving element, from exceeding a predetermined light amount, thereby reducing the amount of reflected light while maintaining the light-receiving sensitivity of the light-receiving element.

[0014] (2) In the above (1), the first collimating lens may have an internal reflective surface, which is provided between the entrance lens and the focal point, and which reflects the first collimated light perpendicularly and emits the second collimated light.

[0015] (3) In the above (1) or (2), the optical receiver may include a second collimating lens that outputs the first collimated light that is incident on the first collimating lens, and an optical splitter that is provided between the first collimating lens and the second collimating lens.

[0016] (4) In the above (3), the first collimating lens and the second collimating lens may be an integrated lens unit, and the lens unit may have a recess between the first collimating lens and the second collimating lens, and the optical demultiplexer may be disposed at the bottom of the recess. In this case, the optical receiver includes a lens unit in which the first collimating lens and the second collimating lens are integrated, which allows for easy and highly accurate assembly of the optical receiver components. Furthermore, the optical components, including the optical demultiplexer disposed between the first collimating lens and the second collimating lens, can be mechanically aligned without any alignment.

[0017] (5) In the above (3), the end face on the output side of the second collimator lens and the end face of the optical demultiplexer may be bonded to each other via an adhesive.

[0018] (6) In any of the above (1) to (5), the curvature of the light receiving lens may be greater than the curvature of the output lens of the first collimating lens.

[0019] [Details of the embodiments of the present disclosure] Specific examples of optical receivers according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to the following examples, but is intended to include all modifications set forth in the claims and within the scope equivalent to the claims. In the description of the drawings, identical or corresponding elements are designated by the same reference numerals, and redundant description will be omitted as appropriate. Furthermore, the drawings may be partially simplified or exaggerated to facilitate understanding, and dimensional proportions and the like are not limited to those shown in the drawings.

[0020] FIG. 1 is a diagram showing a cross section of an optical receiver 1 according to an embodiment. FIG. 1 is a diagram showing a schematic cross section of the optical receiver 1, and some of the components mounted on the optical receiver 1 are not shown. The optical receiver 1 receives a wavelength-multiplexed optical signal in which a plurality of signal lights having a plurality of different wavelengths (for example, λ1 to λ8) are multiplexed. The optical receiver 1 demultiplexes the received wavelength-multiplexed optical signal into a plurality of signal lights and outputs electrical signals corresponding to each signal light. The optical receiver 1 includes a receptacle unit 10, a package unit 20, and a terminal unit 30.

[0021] For convenience, the direction when viewing the receptacle unit 10 from the package unit 20 will be referred to as the "front," "front side," or "forward," and the direction when viewing the package unit 20 from the receptacle unit 10 will be referred to as the "rear," "rear side," or "rearward." However, these directions are for convenience of explanation and do not limit the placement positions of components, etc.

[0022] Receptacle unit 10 couples, for example, a single-mode optical fiber. Receptacle unit 10 has sleeve 11 into which a ferrule of an optical connector external to optical receiver 1 is inserted, holder 12 that joins receptacle unit 10 to package unit 20, and joint sleeve 13 that connects sleeve 11 and holder 12 to each other.

[0023] The package unit 20 houses optical components and a light-receiving element that receives light that has passed through the optical components. For example, the package unit 20 has a rectangular parallelepiped shape. The package unit 20 has, for example, a package frame 21, a bottom wall 22, and a lid 23. The package frame 21 has a rectangular cylindrical shape. The bottom wall 22 forms the bottom of the package unit 20. The bottom wall 22 contains, for example, copper molybdenum or copper tungsten. Since copper molybdenum and copper tungsten have high thermal conductivity, when the bottom wall 22 contains copper molybdenum or copper tungsten, heat dissipation at the bottom wall 22 can be improved.

[0024] The lid 23 is provided to close an opening formed in the upper part of the package frame 21. The lid 23 is fixed to the package frame 21 so as to seal the internal space S of the package unit 20 after the components of the optical receiver 1 are arranged and wired inside the package frame 21. The package unit 20 has, for example, a bush 24. The bush 24 has an annular shape. The surface of the bush 24 facing the front is flat.

[0025] The terminal section 30 is provided for electrical connection of the optical receiver 1 with an external circuit of an external device. The terminal section 30 has, for example, a plurality of laminated ceramic substrates. The terminal section 30 is fixed to the package section 20 in a state where it is fitted into the wall section 21b of the package frame 21. The terminal section 30 electrically connects elements inside the package section 20 with devices external to the optical receiver 1. The terminal section 30 has a high-frequency line and a power supply line.

[0026] Holder 12 of receptacle part 10 is fixed to package part 20 via bushing 24. Sleeve 11 is coupled to holder 12 via joint sleeve 13. Joint sleeve 13 performs alignment in the axial direction (left-right direction in FIG. 1) and radial direction (up-down direction in FIG. 1, and directions perpendicular to the plane of the paper in FIG. 1).

[0027] The receptacle portion 10 has, for example, a stub 14. The stub 14 is disposed inside the sleeve 11. As described above, a ferrule of an external optical connector is inserted into the sleeve 11, and the ferrule holds an external optical fiber. This external fiber is optically coupled to an optical fiber 15 held by the stub 14. The receptacle portion 10 has a lens 16 disposed inside the holder 12. The lens 16 converts light emitted from the optical fiber 15 into, for example, collimated light. Wavelength-multiplexed signal light is emitted from the lens 16, and the wavelength-multiplexed signal light is emitted into the inside of the package portion 20 through an optical window sealed in the bushing 24.

[0028] The package unit 20 has an optical module 40 that demultiplexes the wavelength-multiplexed signal light emitted from the lens 16 into a plurality of signal lights with different wavelengths. The optical module 40 has a support substrate 41, and the optical components of the optical receiver 1 are mounted on the support substrate 41. For example, the optical module 40 has a support member 42, and the support substrate 41 is disposed at a position separated from the bottom wall 22 by the support member 42. The optical components mounted on the support substrate 41 are disposed so as to face the bottom wall 22.

[0029] The package unit 20 has a mirror 43, a first collimating lens 50, and a light-receiving element 45. Each of the multiple signal lights demultiplexed by the optical module 40 is bent by 90° by the mirror 43 and emitted from the mirror 43 toward the bottom wall 22. The first collimating lens 50 has multiple lenses that collect each of the multiple signal lights. The package unit 20 has multiple light-receiving elements 45, and the signal lights collected by each of the multiple lenses are received by each light-receiving element 45.

[0030] The first collimating lens 50 and the light receiving element 45 are mounted on the package unit 20 via, for example, a first mounting substrate 46 mounted on the bottom wall 22 and a second mounting substrate 47 mounted on the first mounting substrate 46. For example, a TIA (Trans Impedance Amplifier) ​​48 is mounted on the first mounting substrate 46 and positioned between the second mounting substrate 47 and the terminal unit 30. The TIA 48 is electrically connected to the light receiving element 45 via, for example, a wire 49. In the following description, the direction in which the light receiving element 45 is provided as viewed from the bottom wall 22 will be referred to as "upper," "upper side," or "above," and the direction in which the bottom wall 22 is provided as viewed from the light receiving element 45 will be referred to as "lower," "lower side," or "below." However, these directions are for convenience of explanation and do not limit the orientation of each part.

[0031] FIG. 2 is an enlarged view of the optical receiver 1 in which the mirror 43, the first collimating lens 50, and the light receiving element 45 are arranged. The optical receiver 1 further includes a first collimating lens 50 arranged between the mirror 43 and the light receiving element 45. The light (signal light) incident on the mirror 43 and the light reflected by the mirror 43 form a first collimated light beam L1 having a predetermined diameter D1. The first collimating lens 50 receives the first collimated light beam L1 reflected by the mirror 43 and converts the first collimated light beam L1 into a second collimated light beam L2 having a diameter D2 smaller than the predetermined diameter D1. The first collimating lens 50 emits the second collimated light beam L2 toward the light receiving element 45.

[0032] The light receiving element 45 is, for example, a photodiode (PD). The light receiving element 45 includes a light receiving lens 45b that receives the second collimated light L2 and a light receiving unit 45c that receives the light L3 collected by the light receiving lens 45b. The light receiving unit 45c is, for example, disk-shaped. The light receiving lens 45b is, for example, a convex lens that protrudes toward the first collimating lens 50 and has a curved surface that faces the first collimating lens 50. The light L3 incident on the light receiving unit 45c is converted into an electrical signal (photocurrent) and transmitted to the TIA 48 via the wire 49 described above. For example, the second collimated light L2 from the first collimating lens 50 is incident perpendicularly to the vertex of the light receiving lens 45b.

[0033] Fig. 3 is an enlarged view of the first collimating lens 50. As shown in Fig. 3, the first collimating lens 50 includes, for example, an entrance lens 51 onto which the first collimated light L1 is incident, a block 52 inside which a focal point L4 is formed upon incidence of the light on the entrance lens 51, and an exit lens 53 that receives light L5 diverging from the focal point L4 and converts the light L5 into second collimated light L2.

[0034] The input lens 51 is a convex lens that protrudes toward the mirror 43 and has a curved surface that faces the mirror 43. The block 52 has, for example, a rectangular parallelepiped shape. The block 52 has a first surface 52b on which the input lens 51 is formed and a second surface 52c facing the opposite side from the first surface 52b, and the output lens 53 is formed on the second surface 52c. The block 52 transmits light L6 collected by the input lens 51, a focal point L4 of the light L6, and light L5 diverging from the focal point L4. The output lens 53 is a convex lens that protrudes toward the light receiving element 45 and has a curved surface that faces the light receiving element 45. The output lens 53 converts the light L5 into second collimated light L2 and emits the converted second collimated light L2 to the light receiving element 45.

[0035] The above describes the effects and advantages obtained from the optical receiver 1 according to this embodiment. The optical receiver 1 includes a first collimating lens 50 having an entrance lens 51 and an exit lens 53, and a light-receiving element 45 having a light-receiving lens 45b and a light-receiving portion 45c. The entrance lens 51 converts the incident first collimated light L1 into light L6, which is a convergent light, and light L5 diverging from a focal point L4 of the light L6 is converted into second collimated light L2 by the exit lens 53. The diameter D2 of the second collimated light L2 is smaller than the diameter D1 of the first collimated light L1. The light-receiving lens 45b of the light-receiving element 45 receives the second collimated light L2, not the convergent light.

[0036] 4, the light receiving lens 45b receives the second collimated light L2, which has a diameter smaller than the first collimated light L1, and thereby the reflected return light L7 from the light receiving lens 45b can be reduced. Therefore, the reflected return light L7 from the light receiving lens 45b, which is the surface of the light receiving element 45, can be prevented from exceeding a predetermined light amount, and the reflected return light L7 can be reduced while maintaining the light receiving sensitivity characteristics of the light receiving element 45. More specifically, the light amount of the reflected return light L7 can be reduced to 1 / 1000 or less of the second collimated light L2.

[0037] Next, an optical receiver according to a first modification will be described with reference to Fig. 5. The optical receiver according to the first modification includes a first collimating lens 50A that is different from the above-described first collimating lens 50. In the following, parts that overlap with the description of the optical receiver 1 described above will be assigned the same reference numerals and will be omitted as appropriate.

[0038] The first collimating lens 50A includes an entrance lens 51 onto which the first collimated light L1 is incident, a block 57 different from the block 52 described above, and an exit lens 58 different from the exit lens 53 described above. As shown in FIGS. 3 and 5, for example, a length A1 of the block 52 in the optical axis direction, which is the direction in which the optical axis X of the first collimated light L1 extends, is shorter than a length A2 of the block 52 in a direction perpendicular to the optical axis. Meanwhile, a length A3 of the block 57 in the optical axis direction is longer than a length A4 of the block 57 in the direction perpendicular to the optical axis. Furthermore, the length A3 is longer than the length A1.

[0039] For example, the curvature of output lens 53 is greater than the curvature of light-receiving lens 45b of light-receiving element 45. Output lens 53 is made of, for example, resin or silicon. The curvature of output lens 58 is less than the curvature of light-receiving lens 45b of light-receiving element 45. That is, in the first modified example, the curvature of light-receiving lens 45b is greater than the curvature of output lens 58 of first collimator lens 50A. Note that it is desirable to keep the tilt angle (mounting angle) of output lens 53 and output lens 58 with respect to optical axis X to within ±0.3°.

[0040] Next, an optical receiver 61 according to a second modification will be described with reference to FIG. 6. FIG. 6 is a diagram schematically illustrating a portion of the configuration of the optical receiver 61. As illustrated in FIG. 6, the optical receiver 61 includes an optical module 70 that is different from the optical module 40. The optical module 70 includes a support substrate 71 disposed at a position spaced apart from the bottom wall 22, and a first collimating lens 72, a second collimating lens 73, and an optical demultiplexer 74 mounted on the support substrate 71. The first collimating lens 72 is located above the light-receiving element 45, and the second collimating lens 73 is located behind the receptacle portion 10. The optical demultiplexer 74 is provided between the first collimating lens 72 and the second collimating lens 73.

[0041] The first collimating lens 72 includes an entrance lens 72b onto which the first collimated light L1 is incident, a block 72c having a focal point L4 formed therein, an exit lens 72d that converts the light L5 into a second collimated light L2, and a reflecting surface 72f that reflects the light L6 from the entrance lens 72b toward the exit lens 72d. The reflecting surface 72f perpendicularly reflects the first collimated light L1 and emits the second collimated light L2. More specifically, the reflecting surface 72f bends the light L6 emitted backward from the entrance lens 72b by 90 degrees and emits the light L6 downward. The focal point L4 of the light L6, which is a convergent light, is formed below the reflecting surface 72f. Then, light L5 that spreads downward from focal point L4 enters output lens 72d, and output lens 72d converts light L5 into second collimated light L2 and outputs second collimated light L2 toward light receiving element 45.

[0042] The second collimating lens 73 has, for example, an incident lens 73b that receives the divergent light L9 from the receptacle portion 10 and converts the divergent light L9 into first collimated light L1, and a block 73c in which the incident lens 73b is provided. The first collimated light L1 is emitted from the incident lens 73b, and the first collimated light L1 emitted from the incident lens 73b passes through the block 73c and reaches the optical splitter 74. The optical splitter 74 splits the first collimated light L1, and each of the first collimated light L1 split by the optical splitter 74 is incident on the first collimating lens 72. As described above, the optical receiver 61 according to the second modification includes the second collimating lens 73 that outputs the first collimated light L1 incident on the first collimating lens 72, and the optical demultiplexer 74 that is provided between the first collimating lens 72 and the second collimating lens 73. This optical receiver 61 also provides the same effects as the optical receiver 1 described above. The block 73c and the optical demultiplexer 74 are bonded together with an adhesive. That is, the end face on the output side of the second collimating lens 73 and the end face on the input side of the optical demultiplexer 74 are bonded together with an adhesive. In this case, it is possible to suppress return light.

[0043] Next, an optical receiver 81 according to a third modification will be described with reference to Fig. 7. Fig. 7 is a diagram schematically illustrating a portion of the configuration of the optical receiver 81. As shown in Fig. 7, the optical receiver 81 has an optical module 90 that is different from the optical module 70 described above. The optical module 90 has an optical demultiplexer 74 and a lens unit 91 in which the first collimating lens 72 and the second collimating lens 73 described above are integrated.

[0044] For example, the lens unit 91 has a recess 92 located between the first collimating lens 72 and the second collimating lens 73, and the optical splitter 74 is disposed in the recess 92. That is, in the lens unit 91, the recess 92 is provided between the first collimating lens 72 and the second collimating lens 73, and the optical splitter 74 is disposed at the bottom of the recess 92. The recess 92 is defined by the incident lens 72b of the first collimating lens 72, the block 73c of the second collimating lens 73, and a bottom surface 92b extending from the block 73c to the incident lens 72b, and the optical splitter 74 is disposed on the bottom surface 92b. The lens unit 91 has a block portion 93 mounted on the bottom wall 22. The second collimating lens 73 is provided on the front side and above the block portion 93, and the first collimating lens 72 is provided on the rear side and above the block portion 93.

[0045] As described above, in the optical receiver 81 according to the third modification, the first collimating lens 72 and the second collimating lens 73 are integrated into the lens unit 91. By including the lens unit 91 in which the first collimating lens 72 and the second collimating lens 73 are integrated in the optical receiver 81, the components of the optical receiver 81 can be assembled easily and with high precision. Furthermore, the optical components including the optical demultiplexer 74 provided between the first collimating lens 72 and the second collimating lens 73 can be mechanically aligned without any alignment.

[0046] The above describes embodiments and various modifications of the optical receiver according to the present disclosure. However, the present invention is not limited to the above-described embodiments or modifications. Those skilled in the art will readily recognize that various modifications and variations are possible within the scope of the claims. For example, the shape, size, number, material, and arrangement of each component of the optical receiver are not limited to those described above and can be modified as appropriate.

[0047] For example, in the above-described embodiment, the receptacle unit 10 includes the sleeve 11, the holder 12, the joint sleeve 13, the stub 14, the optical fiber 15, and the lens 16. However, the configuration of the receptacle unit of the optical receiver is not limited to the above-described example and can be modified as appropriate. The configuration of the package unit and the configuration of the terminal unit are also not limited to the above-described examples and can be modified as appropriate. [Explanation of symbols]

[0048] 1...Optical receiver 10...Receptacle part 11...Sleeve 12...Holder 13...Joint sleeve 14...Stub 15...Optical fiber 16...Lens 20...Package section 21...Package frame 21b...Wall part 22...Bottom wall 23...lid body 24...Bush 30...Terminal section 40...Optical module 41...Support substrate 42...Support member 43...Mirror 45...Photodetector 45b...Receiving lens 45c...light receiving part 46...First mounting board 47...Second mounting board 48...TIA 49…Wire 50, 50A...First collimating lens 51...Inlet lens 52...Block 52b...Side 1 52c…Second side 53...Output lens 57...Block 58...Output lens 61...Optical receiver 70...Optical module 71...Support substrate 72...First collimating lens 72b...Inlet lens 72c...Block 72d...Output lens 72f…Reflective surface 73...Second collimating lens 73b...Inlet lens 73c...Block 74...Optical demultiplexer 81...Optical receiver 90...Optical module 91...Lens unit 92...recess 92b…Bottom surface 93...Block section D1, D2...diameter L3, L5, L6, L7...light L1: First collimated light L2: Second collimated light L4…Focus L9…divergent light S…interior space X…Optical axis

Claims

1. a first collimating lens including an entrance lens into which a first collimated light beam having a predetermined diameter is incident, and an exit lens that receives light beams that are incident on the entrance lens and converged and spread from a focal point, and emits a second collimated light beam having a diameter smaller than the predetermined diameter; a light-receiving element having a light-receiving lens that receives the second collimated light and emits the second collimated light as focused light, and a light-receiving unit that receives the focused light from the light-receiving lens, a second collimator lens that outputs the first collimated light incident on the first collimator lens; an optical demultiplexer provided between the first collimating lens and the second collimating lens, Optical receiver.

2. the first collimating lens has an internal reflective surface; the reflecting surface is provided between the incident lens and the focal point, and reflects the first collimated light perpendicularly and emits the second collimated light.

2. The optical receiver according to claim 1.

3. the first collimating lens and the second collimating lens are an integrated lens unit, In the lens unit, a recess is provided between the first collimator lens and the second collimator lens, the optical demultiplexer is disposed at the bottom of the recess; 2. The optical receiver according to claim 1.

4. an end face on the output side of the second collimator lens and an end face on the input side of the optical demultiplexer are bonded to each other via an adhesive; 2. The optical receiver according to claim 1.

5. The curvature of the receiving lens is greater than the curvature of the output lens of the first collimating lens.

3. The optical receiver according to claim 1.

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