JP2016100480A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module capable of being easily manufactured and being made compact even having a plurality of optical elements and optical systems that are built-in.SOLUTION: An optical module includes: a plurality of light receiving parts provided side by side in a first direction; a first lens disposed in a light path of light incident on a first light receiving part out of the plurality of light receiving parts from a second direction crossing the first direction; and a second lens disposed in the light path of the light incident from the second direction on the second light receiving part adjacent to the first light receiving part out of the plurality of light receiving parts. A first distance between the first light receiving part and the first lens is longer than a second distance between the second light receiving part and the second lens. A difference between the first distance and the second distance is wider than a width of the second lens in the second direction.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to an optical module.

  A WDM (Wavelength Division Multiplexing) type optical communication system is being increased in bit rate. The optical module corresponding to this includes, for example, a plurality of light sources or light receiving units and a plurality of optical systems. On the other hand, market needs for miniaturization of optical modules are universal. For this reason, the technique which arrange | positions a some optical element and each optical system in the limited space of an optical module is calculated | required.

JP 2014-102498 A JP 2014-85639 A JP 2013-125045 A JP 2013-140292 A JP 2013-17161 A JP 2013-2014473 A

  The embodiment provides an optical module that is easy to manufacture and can be miniaturized while incorporating a plurality of optical elements and respective optical systems.

  The optical module according to the embodiment includes a plurality of light receiving units arranged in parallel in a first direction, and light incident on the first light receiving unit from the second direction intersecting the first direction. A first lens disposed in an optical path; a second lens disposed in an optical path of light incident from the second direction on a second light receiving unit adjacent to the first light receiving unit among the plurality of light receiving units; Is provided. Unlike the first distance between the first light receiving unit and the first lens and the second distance between the second light receiving unit and the second lens, the first distance and the second distance are different. The absolute value of the difference between the first lens and the second lens is larger than the width in the second direction of the lenses arranged on the plurality of light receiving portions side of the first lens and the second lens.

  According to the embodiment, it is possible to realize an optical module that is easy to manufacture and can be downsized while incorporating a plurality of optical elements and respective optical systems.

It is a schematic diagram which shows the optical module which concerns on 1st Embodiment. It is a schematic plan view which shows the manufacturing process of the optical module which concerns on 1st Embodiment. It is a schematic plan view which shows the optical module which concerns on a comparative example. It is a schematic diagram which shows the optical module which concerns on the modification of 1st Embodiment. It is a schematic diagram which shows the optical module which concerns on another modification of 1st Embodiment. It is a schematic diagram which shows the optical module which concerns on the other modification of 1st Embodiment. It is a schematic diagram which shows the optical module which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same parts in the drawings are denoted by the same reference numerals, detailed description thereof will be omitted as appropriate, and different parts will be described as appropriate. Also, the arrangement of each component will be described with the axial directions of the XYZ orthogonal coordinate system as the X direction, the Y direction, and the Z direction. In this specification, the Y direction is described as the first direction, and the X direction is described as the second direction.

[First embodiment]
FIG. 1 is a schematic diagram showing an optical module 1 according to the first embodiment. FIG. 1A is a plan view showing the component arrangement of the optical module 1. FIG. 1B is a schematic diagram showing a cross section of the optical module 1.

  The optical module 1 is, for example, a WDM light receiving module. As shown in FIG. 1A, the optical module 1 includes a duplexer 10, a plurality of light receiving units 20a to 20d, and a TIA (Trans-impedance Amplifier) 30. Each component is disposed inside the metal case 40. In this specification, for example, the light receiving units 20a to 20d may be collectively referred to as the light receiving unit 20. In addition, other components may be displayed in the same manner.

  The optical module 1 includes, for example, light receiving elements 25a to 25d. The light receiving elements 25a to 25d include light receiving portions 20a to 20d, respectively. The light receiving unit 20 is, for example, a part having photosensitivity on the surface of the light receiving element 25.

  The metal case 40 includes a base plate 41, a frame 43, and a lid 45. As shown in FIG. 1B, the duplexer 10, the light receiving element 25, and the TIA 30 are disposed on the base plate 41. For example, the duplexer 10 is mounted on the base plate 41 via the adhesive layer 11. The light receiving element 25 is disposed on the side surface 33a of the mount base fixed on the base plate 41 via the adhesive layer 31, for example. For example, the TIA 30 is disposed on the upper surface 33 b of the mount base 33.

As shown in FIG. 1 (a), the metal case 40 has a window 47 for entering the laser beam L _IN transmitted through the optical fiber. The window 47 is provided, for example, in a part of the frame 43 that faces the incident surface 10 a of the duplexer 10.

Demultiplexer 10 demultiplexes the laser beam L _IN entered from the window 47 different plurality of laser beams of wavelengths. The laser beam _LIN is, for example, WDM light obtained by combining four laser beams having different wavelengths. Demultiplexer 10 four laser beams _L 1 ~L ₄ demultiplexes laser light _{L IN.}

The duplexer 10 has an incident surface 10a and an exit surface 10b on the opposite side. Four band pass filters 13a to 13d are arranged on the emission surface 10b. Laser light L _IN incident on the demultiplexer 10 is multiply reflected between the incident surface 10a and the exit surface 10b, and is emitted through a band-pass filter 13 in the process. Bandpass filter 13a~13d is passed through different laser beam _L 1 ~L ₄ wavelengths respectively.

As shown in FIG. 1A, the laser beams L _{1 to} L ₄ propagate in the X direction and enter, for example, a plurality of light receiving units 20a to 20d. The light receiving units 20a to 20d are arranged side by side in the Y direction. Receiving element 25a~25d converts the laser beam _L 1 ~L ₄ into an electric signal, respectively. Output signals from the light receiving elements 25 a to 25 d are output to the outside via the TIA 30. Each of the laser beams L _{1 to} L ₄ is modulated by, for example, a 25 Gbps signal. Then, the optical module 1 outputs an electrical signal of 25 Gbps × 4 channels.

  The light receiving elements 25 a to 25 d are electrically connected to the TIA 30 through the metal wire 35. Each metal wire 35 is preferably provided to have the same length in order to have the same transmission characteristics. Each metal wire 35 preferably has the shortest length in order to transmit a high bit rate signal.

  The TIA 30 is disposed at a position adjacent to the light receiving elements 25a to 25d. The TIA 30 is, for example, a square CMOSIC (Complementary Metal Oxide Semiconductor Integrated Circuit) chip. The light receiving elements 25 a to 25 d are arranged in parallel along one side of the TIA 30.

As shown to Fig.1 (a), the some lenses 50a-50d are arrange | positioned between the splitter 10 and the light-receiving parts 20a-20d. A plurality of lenses 50a~50d are respectively disposed on the optical path of the laser beam _L 1 ~L _4. Lens 50a, for example, converging the laser beam _{L 1} to the light receiving portion 20a. Lens 50b~ lens 50d are respectively condensing the light receiving portion 20b~20d the laser beam _L 2 ~L _4. Here, “condensing” includes a case where focusing is performed so that the spot diameter of the laser beam is minimized on the light receiving unit and a case where defocusing is performed within a range where the spot diameter of the laser beam is within the light receiving unit.

  One of the plurality of light receiving units 20a to 20d is a first light receiving unit, and the other one disposed adjacent to the first light receiving unit is a second light receiving unit. Further, among the laser beams L1 to L4, a lens disposed on the optical path of the laser beam incident on the first light receiving unit is defined as the first lens, and a lens disposed on the optical path of the laser beam incident on the second light receiving unit. Is a second lens. The first distance from the first lens to the first light receiving unit is different from the second distance from the second lens to the second light receiving unit. The absolute value of the difference between the first distance and the second distance is larger than the width in the X direction of the lenses located on the plurality of light receiving portions of the first lens and the second lens in the X direction.

  Here, the first distance and the second distance are, for example, optical path lengths between the lens 50 and the light receiving unit 20. Further, the first distance and the second distance may be the distance between the lens 50 and the light receiving unit 20 in the X direction.

For example, the first light receiving portion of the light receiving portions 20a~20d and (light receiving portion 20a), a first lens disposed in the optical path of the laser light _{L 1} incident on the first light receiving portion (lens 50a), the distance the first distance _{D 1.} The second light receiving portion adjacent to the first light receiving portion of the light receiving portions 20a~20d and (the light receiving portion 20b), a second lens disposed in the optical path of the laser beam L ₂ to be incident on the second light receiving section (lens and 50b), which distance the second distance _{D 2} of.

As shown in FIG. 1 (a), the first distance _{D 1} of the between the light receiving portion 20a and the lens 50a is longer than the second distance _{D 2} between the light receiving portion 20b and the lens 50b. Furthermore, the first distance _{D 1} and the difference between the second distance _{D 2} is greater than the width _{W L} of the X direction of the lens 50b. The focal length of the lens 50a for condensing the laser beam _{L 1} to the light receiving portion 20a is longer than the focal length of the lens 50b for condensing the laser beam _{L 2} to the light receiving portion 20b. This relationship is the same when, for example, the first light receiving unit is the light receiving unit 20c and the second light receiving unit is the light receiving unit 20b.

  Thus, two adjacent lenses among the lenses 50a to 50d are arranged so as not to overlap when viewed in the Y direction. As a result, the lenses 50a to 50d can be easily mounted, and the manufacturing cost can be reduced.

In the optical module 1, the light receiving surface 25 f of the light receiving element 25 faces the emission surface 10 b of the duplexer 10. Therefore, the laser beam L _X emitted from the duplexer 10 passes through the lens 50 and directly enters the light receiving unit 20 of the light receiving element 25. Therefore, condensing the laser beam L _X by the lens 50 is facilitated. For example, the optical module 1 is advantageous when the area of the light receiving unit 20 is small.

  Next, a method for manufacturing the optical module 1 according to the first embodiment will be described with reference to FIGS. FIG. 2A to FIG. 2C are schematic plan views showing an example of the mounting process of the lens 50.

As shown in FIG. 2 (a), demultiplexer 10, in a state where the light receiving element 25a~25d and TIA30 placed inside a metal case 40, placing the lens 50a in the optical path of the laser beam _{L 1.}

  The lens 50a is, for example, a rod lens molded into a rectangular parallelepiped shape. The lens 50a is mounted on the base plate 41 via the adhesive layer 53a. For the adhesive layer 53a, for example, an ultraviolet curable adhesive is used.

For example, an ultraviolet curable adhesive is applied to the position where the lens 50a is disposed on the base plate 41, and the lens 50a is placed thereon. Next, adjust the position of the lens 50a while irradiating the laser beam L _1. Specifically, for example, the lens 50a is disposed on the adhesive from above the base plate 41 in a state of being attracted to a collet (not shown). Subsequently, while monitoring the output of the light receiving element 25a, the collet is moved back and forth in the X direction and the Y direction, respectively, and the angle is finely adjusted in the rotation direction with the Z direction as the central axis, so that the output intensity of the light receiving element 25a is The lens 50a is held at the maximum position. Subsequently, the adhesive is cured by irradiating with ultraviolet light. Thereby, the lens 50a is fixed to the optimal position via the adhesive layer 53a.

Next, as shown in FIG. 2 (b), placing a lens 50c on the optical path of the laser beam _{L 3.} The lens 50c is disposed at a position where the optical path of the laser beam L2 is interposed between the lens 50a and the lens 50a. For this reason, the space | interval of the lens 50a and the lens 50c is securable. Therefore, the lens 50c can be fixed at the optimum position without being obstructed by the adhesive layer 53a to which the lens 50a is fixed. For example, when the lens 50c is disposed at a position close to the lens 50a, there is a case where the lens 50c cannot be fixed at the optimum position because of being blocked by the adhesive layer 53a.

Next, as shown in FIG. 2 (c), placing a lens 50b on the optical path of the laser beam _{L 2.} The lens 50b is disposed at a position shifted in the X direction from the lenses 50a and 50c. That is, the lens 50b can be disposed at a position away from the adhesive layers 53a and 53c that fix the lenses 50a and 50c. Accordingly, the lens 50b can be positioned while irradiating the laser beam L2 so that the light output of the light receiving element 25b is maximized without being hindered by the adhesive layers 53a and 53c.

Then, to fix the lens 50d in the optical path of the laser beam L ₄ in the same procedure. As shown in FIG. 1A, the lens 50d is also fixed at a position shifted in the X direction with respect to the lens 50c. Therefore, it can be fixed at the optimum position without being obstructed by the adhesive layer 53c that fixes the adjacent lens 50c.

For example, the focal length F1 of the lens 50a is preferably longer than the focal length F2 of the lens 50b. More preferably, the difference between the focal length F1 and the focal length F2 is larger than the width W _L of the lens 50b in the X direction.

For example, in the case where the laser beam L ₁ was placed lens 50a at a position for condensing the light receiving section 20a, the output of the light receiving element 25a is maximized. The lens 50a is fixed at the optimum position. Lens 50b likewise is fixed to the optimum position for focusing the laser beam L ₂ to the light receiving portion 20b. Then, the focal length F1 of the lens 50a, and the difference of the focal length F2 of the lens 50b is greater than _{W L,} the lens 50a and the first distance _{D 1} of the between the light receiving portion 20a, a lens 50b and the light receiving portion 20b the second difference in distance _{D 2} between the is larger than _{W L.}

  Although it depends on the area of the light receiving unit 20, it is not necessary to focus so that the spot diameter of the laser beam at each light receiving unit is minimized. In the state where the laser beam is defocused, if the spot diameter of the laser beam is smaller than the diameter of each light receiving portion, the output of the light receiving element 25 can be maximized. The position where the spot diameter is realized can be said to be the optimum position of each lens. Further, if the light receiving portions are focused so that the spot diameter of the laser beam is minimized, the tolerance of the lens position can be maximized. That is, by minimizing the spot diameter of the laser beam, the tolerance of the spot position of the laser beam in the light receiving unit can be maximized. As a result, it is possible to suppress the output fluctuation of the light receiving element with respect to the deviation of the lens position due to the temperature fluctuation or the like, and the reliability of the optical module can be improved.

As described above, it is preferable that the difference between the focal length F1 of the lenses 50a and 50c and the focal length F2 of the lenses 50b and 50d is larger than the width W _L of the lenses 50b and 50d in the X direction. Thereby, the reliability of the optical module 1 can be improved.

  Next, an optical module 2 according to a comparative example will be described with reference to FIG. FIG. 3 is a schematic plan view showing the optical module 2 according to the comparative example.

The optical module 2 shown in FIG. 3 includes a metal case 60, a duplexer 70 disposed therein, a plurality of light receiving elements 25a to 25d, and a TIA 80. The light receiving elements 25a to 25d are arranged in parallel in the Y direction along one side of the TIA 80. The light receiving portions 20a to 20d of the light receiving elements 25a to 25d are also arranged in parallel in the Y direction. Lenses 55a to 55d are disposed between the duplexer 10 and the light receiving elements 25a to 25d. Lens 55a~55d is disposed on the optical path of the laser beam _L 1 ~L ₄ respectively.

In this example, the lenses 55a to 55d have the same focal length and are arranged in parallel in the Y direction. For example, the lens 55a focuses the laser light _{L 1} to the light receiving portion 20a. Lens 55b condenses the laser beam _{L 2} to the light receiving portion 20b. The distance from the lens 55a to the light receiving unit 20a is the same as the distance from the lens 55b to the light receiving unit 20b. That is, the distance between each lens 55 and the corresponding light receiving unit 20 is equal.

  Thus, in the optical module 2, the focal length of the lens 55 is the same. On the other hand, the optical module 1 uses at least two types of lenses 50 having different focal lengths. Therefore, in the optical module 2, the number of parts can be reduced as compared with the optical module 1. As a result, the manufacturing cost of the optical module 2 can be reduced as compared with the optical module 1.

  However, when the wavelength multiplexing degree of WDM increases and the number of laser beams to be demultiplexed increases, the optical module 2 cannot avoid an increase in size. In the optical module 2, there is a limit to narrowing the interval between the lenses 55 arranged in parallel in the Y direction, and the size increases as the multiplicity of wavelengths increases.

  For example, when the distance between the lenses 55 in the Y direction is narrowed, the adhesive layer 53 of the lens fixed first prevents adjustment of the position of the lens 55 disposed adjacently. For this reason, it becomes difficult to arrange all of the lenses 55 at the optimum positions. Even if it is possible to suppress the spread of the adhesive layer 53 on the base plate and suppress the interference with the adjacent lens, the position adjustment may be difficult. For example, there is a case where a collet that attracts a newly arranged lens 55 comes into contact with the adjacent lens 55, and the range of position adjustment is limited.

  On the other hand, in the optical module 1 according to the present embodiment, the adjacent lenses 50 are arranged so as not to overlap when viewed in the Y direction. As a result, even when the multiplicity of wavelengths is increased and the number of arranged lenses is increased, it is possible to secure a range of position adjustment of each lens while suppressing an increase in module size. That is, according to the embodiment, the lens arrangement of the optical module is facilitated, and a small and highly reliable optical module can be realized.

  4 and 5 are schematic views showing optical modules 3 to 5 according to modifications of the first embodiment. FIG. 4A is a plan view showing the component arrangement of the optical module 3. FIG. 4B is a cross-sectional view of the optical module 3. FIGS. 5A and 5B are cross-sectional views of the optical modules 4 and 5.

  As shown in FIG. 4A, the optical module 3 includes a duplexer 10, a plurality of light receiving elements 25a to 25d, and a TIA 30. The light receiving elements 25a to 25d include light receiving portions 20a to 20d, respectively. The light receiving elements 25a to 25d are arranged along one side of the TIA 30 and are arranged in the Y direction. Lenses 50a to 50d are arranged between the duplexer 10 and the light receiving elements 25a to 25d.

  For example, the first distance D1 from the lens 50c to the light receiving unit 50c is wider than the second distance D2 from the lens 50b to the light receiving unit 20b or the second distance D2 from the lens 50d to the light receiving unit 20d. The difference between the first distance D1 and the second distance D2 is larger than the width WL in the X direction of the lenses 50b and 50d.

Further, the interval W1 between the light receiving element 25a and the lens 50a is wider than the interval W2 between the light receiving element 25b and the lens 50b. Further, the difference between the interval W1 between the light receiving element 25a and the lens 50a and the interval W2 between the light receiving element 25b and the lens 50b is larger than the width W _{L in} the X direction of the lens 50b. The distance between the light receiving element 25c and the lens 50c, the distance between the light receiving element 25b and the lens 50b, or the distance between the light receiving element 25d and the lens 50d have the same relationship.

  As shown in FIG. 4B, the light receiving element 25 is mounted on the reflecting prism 23 fixed on the base plate 41 via the adhesive layer 21, for example. The reflecting prism 23 changes the propagation direction of the laser light LX from the X direction to the Z direction and makes it incident on the light receiving unit 20. With this arrangement, the upper surface of the light receiving element 25 and the upper surface of the TIA 30 can be positioned in parallel or in the same plane. Thereby, the light receiving element 25 and the TIA 30 can be connected by the metal wire 35 having the shortest length.

  The optical module 4 shown in FIG. 5A includes a duplexer 10, a plurality of light receiving elements 25, a TIA 30, and an optical mirror 27. The light receiving element 25 and the TIA 30 are mounted on the base plate 41 via the adhesive layers 21 and 31, for example. The plurality of light receiving elements 25 are juxtaposed in the Y direction along one side of the TIA 30. Thereby, the light receiving element 25 and the TIA 30 can be connected by the metal wire 35 having the shortest length. The light receiving element 25 includes the light receiving unit 20, and the optical mirror 27 is disposed above the light receiving unit 20.

  The optical module 4 includes a plurality of lenses 50 disposed between the duplexer 10 and the optical mirror 27. The optical mirror 27 converts the propagation direction of the laser light LX that has passed through the lens 50 from the X direction to the −Z direction, and causes the laser light LX to enter the light receiving unit 20.

  The positional relationship between the plurality of lenses 50 and the optical mirror 27 is the same as the positional relationship between the lenses 50a to 50d and the light receiving units 20a to 20d shown in FIG. That is, the first distance from the lens 50 that condenses the laser light to one light receiving unit 20 among the plurality of light receiving elements 25 to the optical mirror 27 is the laser light to the other light receiving unit 20 adjacent to the light receiving unit 20. This is different from the second distance from the other lens 50 that collects the light to the optical mirror 27. The absolute value of the difference between the first distance and the second distance is larger than the width WL in the X direction of the lens 50 disposed on the optical mirror side.

  The optical module 5 shown in FIG. 5B includes a duplexer 10, a plurality of light receiving elements 29, and a TIA 30. For example, the light receiving element 29 and the TIA 30 are arranged on a mount base 37 fixed on the base plate 41 via an adhesive layer 39. The plurality of light receiving elements 29 are juxtaposed in the Y direction along one side of the TIA 30. Thereby, the light receiving element 29 and the TIA 30 can be connected by the metal wire 35 having the shortest length.

  The light receiving element 29 is, for example, an end face incident type device. That is, the light receiving element 29 has a light receiving portion provided in a waveguide shape, and has a structure in which the laser light LX is incident on one end face of the waveguide.

  The optical module 5 includes a plurality of lenses 50 disposed between the duplexer 10 and the light receiving element 29. The positional relationship between the plurality of lenses 50 and the light receiving element 29 is the same as the positional relationship between the lenses 50a to 50d and the light receiving portions 20a to 20d shown in FIG. That is, the first distance from the lens 50 that condenses the laser light to one of the plurality of light receiving elements 29 to the end face of the light receiving element 29 is that the laser light is condensed to another adjacent light receiving element 29. This is different from the second distance from the lens 50 to the end face of the light receiving element 29. The absolute value of the difference between the first distance and the second distance is larger than the width WL in the X direction of the lens 50 disposed on the light receiving element 29 side.

  FIG. 6 is a schematic plan view showing an optical module 6 according to another modification of the first embodiment. In the optical module 6, the light receiving element 120 is disposed adjacent to the TIA 130. The light receiving element 120 includes a plurality of light receiving portions 20a to 20d arranged in parallel in one direction. The light receiving element 120 is arranged at a position where the long side is parallel to one side of the TIA 130. As a result, the plurality of light receiving units 20a to 20d are arranged in the Y direction, for example. The light receiving units 20a to 20d are electrically connected to the TIA 130 via the metal wires 35, respectively.

As described above, by providing a plurality of light receiving portions 20 in one light receiving element 120, the interval between the adjacent light receiving portions 20 can be reduced. That is, the interval between the laser beams L _{1 to} L ₄ incident on each light receiving unit 20 can be reduced, and the optical module 6 can be downsized. It is also possible to realize an optical module that is compatible with a highly multiplexed WDM system.

As shown in FIG. 6, when the lenses 50 a to 50 d are viewed in the X direction, the lenses 50 a to 50 d can be arranged so that a part of each overlaps between adjacent lenses. That is, as long as the optical paths of the laser beams L _{1 to} L ₄ are not blocked, a part of each lens 50 may be arranged to overlap when viewed in the X direction. By using such a lens arrangement, it is possible to cope with a narrower interval between the laser beams L _{1 to} L ₄ .

  FIG. 7 is a schematic diagram showing an optical module 7 according to the second embodiment. The optical module 7 includes a duplexer 150 disposed inside the metal case 90, a light receiving element 160 having a plurality of light receiving portions 20a to 20h, and a TIA 170.

Duplexer 150, an input light _{L IN} made incident from the incident surface 150a, and outputs a plurality of laser beams _L 1 ~L ₈ demultiplexed to. The input light _LIN is, for example, WDM light obtained by combining eight laser beams having different wavelengths. Eight band pass filters 15 a to 15 h that pass light having different wavelengths are attached to the emission surface 150 b of the duplexer 150. The eight laser beams L _{1 to} L ₈ output from the band pass filters 15a to 15h propagate in the X direction and are condensed on the light receiving units 20a to 20h through the lenses 57a to 57h, respectively.

The light receiving element 160 converts the laser beams L _{1 to} L ₈ incident on the light receiving portions 20 a to 20 h into electrical signals and outputs the electrical signals to the TIA 170. For example, if the laser beams L _{1 to} L ₈ are each modulated with a 25 Gbps signal, the TIA 170 outputs an electrical signal of 25 Gbps × 8 channels.

The optical module 7 can transmit, for example, twice the amount of information as the optical module 1 shown in FIG. 1, but its size is desired to be smaller than twice that of the optical module 1. In order to reduce the size of the optical module 7, for example, it is preferable to reduce the size in the Y direction of the duplexer 150, the light receiving element 160, and the TIA 170. As a result, the interval between adjacent laser beams among the laser beams L _{1 to} L ₈ output from the duplexer 150 is reduced.

In the optical module 7, for example, the interval W ₁ between one of the two adjacent lenses among the lenses 57 a to 57 h and the light receiving element 160 is the interval between the other lens and the light receiving element 160. wider than W _2. Then, the difference between the distance W ₁ and spacing W ₂ is greater than the width of the X direction of the other lens.

  Further, the optical module 7 uses three types of lenses having different focal lengths. For example, the lenses 57a, 57d, and 57g have a focal length F1. The lenses 57b, 57e, and 57h have a focal length F2. The lenses 57c and 57f have a focal length F3. Each lens 57 has a relationship of focal length F1> focal length F2> focal length F3, and the difference between F1 and F2 is larger than the width in the X direction of each of the lenses 57b, 57e and 57h. The difference between F2 and F3 is larger than the width in the X direction of the lenses 57c and 57f.

  By arranging the lenses 57a to 57h in this way, the distance between the lenses can be widened. As a result, the lenses 57a to 57h can be fixed at the optimum positions. Moreover, in the optical module 7, the space | interval of the adjacent laser beam can be made narrower than the optical module 1 shown in FIG.

  The present invention has been described above with reference to the first embodiment and the second embodiment. However, the present invention is not limited to these embodiments. For example, the present invention is not limited to the case where the first direction and the second direction are orthogonal to each other, and the laser light may be incident on the light receiving element from an oblique direction. That is, the first direction and the second direction intersect.

  In the above embodiment, the arrangement of the light receiving element and the lens has been described as an example. However, for example, the present invention can also be applied to the case where laser light is condensed on a multiplexer. In such a case, the incident region of the bandpass filter disposed on the incident surface of the multiplexer is the light receiving unit.

  Furthermore, embodiments having the same technical idea as the present invention, such as design changes and material changes that can be made by those skilled in the art based on the technical level at the time of filing, are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1-7 ... Optical module 10, 70, 150 ... Demultiplexer, 10a, 150a ... Incident surface, 10b, 150b ... Output surface, 11, 21, 31, 53 ... Adhesion Layer, 13, 15 ... band-pass filter, 20 ... light receiving unit, 25, 29, 120, 160 ... light receiving element, 23 ... reflecting prism, 25f ... light receiving surface, 30, 80, 130, 170 ... TIA, 33, 37 ... Mount base, 35 ... Metal wire, 40, 60, 90 ... Metal case, 41 ... Base plate, 43 ... Frame, 45. ..Lid, 47 ... window, 50, 55, 57 ... lens, L _IN , L _{1 to} L ₈ ... laser beam

Claims (6)

A plurality of light receiving units arranged in parallel in the first direction;
A first lens disposed in an optical path of light incident on a first light receiving unit among the plurality of light receiving units from a second direction intersecting the first direction;
A second lens disposed in an optical path of light incident from the second direction to a second light receiving unit adjacent to the first light receiving unit among the plurality of light receiving units,
The first distance from the first lens to the first light receiving unit is different from the second distance from the second lens to the second light receiving unit,
The absolute value of the difference between the first distance and the second distance is larger than the width in the second direction of the lenses disposed on the plurality of light receiving portions of the first lens and the second lens. module.   The optical module according to claim 1, wherein a focal length of the first lens is different from a focal length of the second lens.   The absolute value of the difference between the focal length of the first lens and the focal length of the second lens is the second direction of the lens disposed on the plurality of light receiving portions of the first lens and the second lens. The optical module according to claim 1, wherein the optical module is larger than the width of the optical module.   The optical module according to claim 1, further comprising a plurality of light receiving elements each having one of the plurality of light receiving units. The first light receiving element having the first light receiving part among the plurality of light receiving elements and the first lens and the second light receiving part among the plurality of light receiving elements. The second distance between the second light receiving element and the second lens is different,
The absolute value of the difference between the first interval and the second interval is larger than the width in the second direction of the lenses disposed on the plurality of light receiving portions of the first lens and the second lens. Item 5. The optical module according to Item 4. One light receiving element including the plurality of light receiving parts,
The first distance between the first lens and the light receiving element is different from the second distance between the second lens and the light receiving element.
The absolute value of the difference between the first interval and the second interval is larger than the width in the second direction of a lens arranged on the light receiving element side of the first lens and the second lens. The optical module as described in any one of 1-3.

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