Optical Module

Abstract

The optical module (100) comprises: a semiconductor laser (1), a light receiver (12) and a lens (3) mounted on a carrier (5); an optical fiber (4); and a control circuit (20) for controlling an injection current (Iop) of the laser (1) so that an output current (Im) of the light receiver (12) receiving a monitoring light (17) becomes constant. At least a portion of the light receiver (12) and the lens (3) are fixed to the carrier (5) by resin bonding materials (7, 8) that shrink by thermal curing. The initial positions of the laser (1), the end portion of the optical fiber (4), the light receiver (12) and the lens (3) with respect to the back surface (24) of the carrier (5) are determined so that the optical coupling efficiency of the laser (1) and the light receiver (12) and the optical fiber (4) change in the same manner with respect to the exposure time of the optical module (100) to an ambient temperature higher than room temperature.

Description

Technical Field

[0001] The present application relates to an optical module. Background Art

[0002] The optical module used for sending optical signals in optical communication systems has a semiconductor laser as a light source for sending optical signals, a light receiving element such as a monitoring photodiode, and an optical fiber. The outgoing light emitted from the front end face of the semiconductor laser is introduced into the optical fiber and used as the output light of the optical module. The outgoing light emitted from the rear end face of the semiconductor laser is introduced into the light receiving element, and the light receiving element outputs a light absorption current proportional to the light receiving power as a monitoring current. In order to achieve stable communication, it is hoped that the output optical power of the optical module is always constant. However, the optical output power may change due to the two reasons described below.

[0003] The first reason is the reduction in the luminous efficiency of the semiconductor laser. When the semiconductor laser is powered on for a long time, it will degrade and its luminous efficiency will decrease. That is, the light output when a constant injection current is applied to the semiconductor laser decreases over time. However, this problem can be solved by using automatic light output control (Auto Power Control (APC)) of the light receiving element. As mentioned above, the light receiving element outputs a monitoring current proportional to the light received power. The value of the injection current is feedback controlled in such a way that the monitoring current becomes constant even if the luminous efficiency of the semiconductor laser decreases, and the value of the injection current is increased according to the decrease in the monitoring current, thereby suppressing the decrease in light output. Such control is called automatic light output control (APC).

[0004] The second reason is the relative position shift between the semiconductor laser and the optical fiber. For example, if the temperature around the optical module changes, the components that hold the semiconductor laser and the optical fiber are thermally deformed according to their materials. If the thermal deformation amounts of the components that hold the semiconductor laser and the optical fiber are different, a relative position shift occurs between the semiconductor laser and the optical fiber, and the amount of light introduced into the optical fiber (introduced optical power) changes. That is, the ratio of the power of the light introduced into the optical fiber and propagated, that is, the introduced optical power, to the power of the light incident on the optical fiber, that is, the emitted optical power, that is, the optical coupling efficiency changes. In Patent Document 1, as a previous example, an optical module is disclosed in which an optical fiber for introducing the output light of the semiconductor laser is fixed to a core column as a packaging component using a resin fixing material. In the optical module described as a previous example in Patent Document 1, since the semiconductor laser is fixed to the core column via solder and a submount, and the optical fiber is fixed to the core column via a resin fixing material, a relative position shift occurs between the semiconductor laser and the optical fiber due to thermal deformation of the resin fixing material.

[0005] In Patent Document 1 Figure 5 , Figure 6 The optical module disclosed in the invention reduces the relative position shift between the semiconductor laser and the optical fiber when the optical fiber is fixed to the core column by sandwiching an adjustment body made of a material having the same thermal expansion coefficient as the core column between the optical fiber and the core column. In order to reduce the relative position shift, measures such as making the thermal deformation of each component of the semiconductor laser and the optical fiber consistent or reducing the thermal deformation are generally taken, but due to various design constraints, it is difficult to completely eliminate the relative position shift.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 59-149075 ( Figure 1 , Figure 2 , Figure 5 , Figure 6 )

[0007] Optical modules sometimes sandwich a lens between a semiconductor laser and an optical fiber, and direct the outgoing light, which is focused by the lens and has a smaller beam size, i.e., a beam diameter, into the optical fiber. Generally speaking, optical semiconductor elements such as semiconductor lasers are heated to about 300°C and fixed to metal, ceramic, and other components by soldering to obtain high heat dissipation. On the other hand, optical components such as lenses and optical fibers combined with semiconductor lasers do not have heat resistance that can be fixed by soldering, so they are fixed to metal, ceramic, and other components using UV-curable resins that do not require heating. Generally speaking, even if an optical module for optical communication is exposed to a high temperature environment of 75 to 95°C for a reference time of about 2000 hours, the variation of light output is required to fall within ±0.5dB.

[0008] If such an optical module is exposed to a high temperature environment of 75 to 95°C, the resin that fixes the lens and optical fiber will undergo irreversible thermal curing shrinkage. On the other hand, since the solder that fixes the semiconductor laser does not cause thermal curing shrinkage, the semiconductor laser and the lens and optical fiber will maintain an irreversible relative position shift. Figure 5 , Figure 6 Such an adjustment body reduces the relative position shift between the semiconductor laser and the optical fiber. When optical components such as lenses other than optical fibers are sandwiched, the relative position shift between the semiconductor laser and the optical fiber, which includes the position shift of the optical components, will also be accumulated, that is, the composite relative position shift between the semiconductor laser and the optical fiber. The reduction in optical coupling efficiency caused by the relative position shift between the semiconductor laser and the optical component or the composite relative position shift between the semiconductor laser and the optical fiber will cause changes in light output. Even if automatic light output control is used, without special measures, it is impossible to suppress the light output changes caused by the irreversible relative position shift between the semiconductor laser and the optical component. Summary of the invention

[0009] The purpose of the technology disclosed in this specification is to provide an optical module capable of suppressing fluctuations in light output when irreversible composite relative positional displacement due to a high temperature environment occurs between a semiconductor laser and an optical fiber with optical components interposed therebetween.

[0010] An example of an optical module disclosed in the present application specification is an optical module that transmits the output light emitted by a semiconductor laser through an optical fiber. The optical module includes: a semiconductor laser and an optical fiber; a light receiver that receives monitoring light emitted from the end face opposite to the output end face from which the output light is emitted; a lens that focuses the output light; a carrier that carries the semiconductor laser, the light receiver, and the lens; and a control circuit that controls the injection current of the semiconductor laser so that the output current of the light receiver becomes constant. The semiconductor laser is fixed to the carrier by a metal bonding material, at least a portion of the light receiver and the lens are fixed to the carrier by a first resin bonding material and a second resin bonding material that produce thermal curing shrinkage, respectively, and the position of the terminal portion of the optical fiber into which the output light is introduced is fixed with reference to the back side of the carrier opposite to the surface of the mounting portion on which the semiconductor laser, the light receiver, and the lens are mounted. The optical coupling efficiency of the semiconductor laser and the light receiver, and the optical coupling efficiency of the semiconductor laser and the optical fiber relative to the exposure time of the optical module to an ambient temperature higher than room temperature are set as a first optical coupling efficiency characteristic and a second optical coupling efficiency characteristic, respectively, so that the change trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same, and the initial positions of the semiconductor laser, the terminal end of the optical fiber, the light receiver, and the lens when the exposure time of the optical module is 0 are determined with reference to the back side of the carrier.

[0011] An optical module of an example disclosed in the present application specification determines the initial positions of a semiconductor laser, an end portion of an optical fiber, a lens, and a light receiver with respect to the back side of a carrier in such a manner that the changing trends of a first optical coupling efficiency characteristic and a second optical coupling efficiency characteristic generated with the passage of exposure time become the same. Therefore, when an irreversible composite relative position shift caused by a high temperature environment occurs between the semiconductor laser and the optical fiber, changes in light output can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram showing an optical module according to the first embodiment.

[0013] Figure 2 Yes means Figure 1 Diagram showing the initial positions of the semiconductor laser and the light receiving element.

[0014] Figure 3 Yes means Figure 1 A diagram showing the positions of a semiconductor laser and a light-receiving element after a reference time has passed.

[0015] Figure 4 Yes means Figure 1 A diagram of the monitor light at the light receiving surface of the light receiving element.

[0016] Figure 5 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element according to the first embodiment.

[0017] Figure 6 This is a diagram showing the optical coupling efficiency characteristics between the semiconductor laser and the optical fiber according to the first embodiment.

[0018] Figure 7 This is a diagram showing a first example of an optical module according to the second embodiment.

[0019] Figure 8 Yes means Figure 7 Diagram showing the initial positions of the semiconductor laser and the light receiving element.

[0020] Fig. 9 Yes means Figure 7 A diagram showing the positions of a semiconductor laser and a light-receiving element after a reference time has passed.

[0021] Fig.10 Yes means Figure 7 A diagram of the monitor light at the light receiving surface of the light receiving element.

[0022] Fig.11 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element according to the second embodiment.

[0023] Fig.12 This is a diagram showing a first example of optical coupling efficiency characteristics between a semiconductor laser and an optical fiber according to the second embodiment.

[0024] Fig.13 This is a diagram showing a second example of the optical coupling efficiency characteristics between the semiconductor laser and the optical fiber according to the second embodiment.

[0025] Fig.14 This is a diagram showing a third example of the optical coupling efficiency characteristics between the semiconductor laser and the optical fiber according to the second embodiment.

[0026] Fig.15 This is a diagram showing a second example of the optical module according to the second embodiment.

[0027] Fig.16 Yes means Fig.15 Diagram showing the position changes of the lens and laser.

[0028] Fig.17 This is a diagram showing a first example of an optical module according to the third embodiment.

[0029] Fig.18 Yes means Fig.17 A diagram showing the optical coupling efficiency characteristics of a semiconductor laser and a light-receiving element.

[0030] Fig.19 This is a diagram showing a second example of the optical module according to the third embodiment.

[0031] Fig. 20 Yes means Fig.19 A diagram showing the optical coupling efficiency characteristics of a semiconductor laser and a light-receiving element.

[0032] Fig.21 It is a diagram showing an optical module according to a fourth embodiment.

[0033] Fig. 22 Yes means Fig.21 A diagram showing the position changes of the light receiving element and the light receiving limit point of the monitoring light.

[0034] Fig.23 It is a diagram showing the position change of the light receiving limit point of the light receiving element and the monitor light of the comparative example.

[0035] Fig.24 This is a diagram showing an optical module according to the fifth embodiment.

[0036] Fig.25 Yes means Fig.24 A diagram showing a monitor light lens and a position change of the monitor light.

[0037] Fig.26 Yes means Fig.24 A diagram of the monitor light at the light receiving surface of the light receiving element.

[0038] Fig. 27 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element involved in the fifth embodiment.

[0039] Fig.28 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the optical fiber involved in the fifth embodiment.

[0040] Fig.29 This is a diagram showing a first example of an optical module according to the sixth embodiment.

[0041] Fig.30 Yes means Fig.29 FIG. 1 is a diagram of the main parts of the mounting section of the light receiver.

[0042] Fig.31 Yes means Fig.29 A diagram showing a monitor light lens and a position change of the monitor light.

[0043] Fig.32Yes means Fig.29 A diagram of the monitor light at the light receiving surface of the light receiving element.

[0044] Fig.33 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element involved in the sixth embodiment.

[0045] Fig.34 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the optical fiber involved in the sixth embodiment.

[0046] Fig.35 This is a diagram showing a second example of the optical module according to the sixth embodiment.

[0047] Fig.36 Yes means Fig.35 FIG. 1 is a diagram of the main parts of the mounting section of the light receiver.

[0048] Fig.37 Yes means Fig.35 A diagram showing a monitor light lens and a position change of the monitor light.

[0049] Fig.38 This is a diagram showing the main part of a third example of the optical module according to the sixth embodiment.

[0050] Fig.39 Yes means Fig.38 A diagram showing a monitor light lens and a position change of the monitor light. DETAILED DESCRIPTION

[0051] Implementation Method 1

[0052] Figure 1 This is a diagram showing an optical module according to the first embodiment. Figure 2 Yes means Figure 1 Figure 1 shows the initial positions of the semiconductor laser and the light receiving element. Figure 3 Yes means Figure 1 A diagram showing the positions of a semiconductor laser and a light-receiving element after a reference time has passed. Figure 4 Yes means Figure 1 A diagram of the monitor light on the light receiving surface of the light receiving element. Figure 5 is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element according to the first embodiment. Figure 6: is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and optical fiber involved in embodiment 1. The optical module 100 includes: a semiconductor laser 1 that emits an output light 16 and a monitoring light 17; a light receiver 12 that receives the monitoring light 17; a lens 3 that focuses the output light 16; an optical fiber 4 that propagates the output light 16 focused by the lens 3; a carrier 5 that carries the semiconductor laser 1, the light receiver 12, and the lens 3; and a control circuit 20 that controls the injection current Iop of the semiconductor laser 1. Figure 1 , an example is shown in which the carrier 5 is fixed to the housing 50, and the terminal portion of the optical fiber 4 is fixed to a holder 51 provided in the housing 50. The output light 16 is the output light of the optical module 100 input to the optical receiving module etc. via the lens 3 and the optical fiber 4, and the monitor light 17 is used to control the injection current Iop of the semiconductor laser 1.

[0053] The semiconductor laser 1, the light receiver 12 and the lens 3 are mounted on the surface of the carrier 5, and the back side 24 of the carrier 5 is fixed to the housing 50. The back side 24 of the carrier 5 serves as a reference for the positions of the semiconductor laser 1, the light receiver 12, the lens 3 and the optical fiber 4 in a direction perpendicular to the back side 24. Here, the direction perpendicular to the back side 24 is the Y direction, the direction perpendicular to the Y direction and the traveling direction of the emitted light 16 is the Z direction, and the direction perpendicular to the Y direction and the Z direction is the X direction. The semiconductor laser 1 emits the emitted light 16 from the first end face 71 on the positive side in the Z direction, that is, on the side of the lens 3, and emits the monitoring light 17 from the second end face 72 on the negative side in the Z direction, that is, on the side of the light receiver 12. In the first embodiment, an example in which the light receiver 12 is a waveguide type light receiving element 2 is shown.

[0054] The semiconductor laser 1 is fixed to the surface of the first mounting portion 25 of the carrier 5 by the metal bonding material 6 that does not shrink upon thermal curing. The light receiving element 2 as the light receiving device 12 is fixed to the surface of the third mounting portion 27 of the carrier 5 by the resin bonding material 7 that shrinks upon thermal curing, and the lens 3 is fixed to the surface of the second mounting portion 26 of the carrier 5 by the resin bonding material 8 that shrinks upon thermal curing. The second mounting portion 26, the first mounting portion 25, and the third mounting portion 27 are arranged from the side close to the optical fiber 4. The range from the dotted line 53a to the dotted line 53b is the second mounting portion 26, the range from the dotted line 53b to the dotted line 53c is the first mounting portion 25, and the range from the dotted line 53c to the dotted line 53d is the third mounting portion 27. The second mounting portion 26 is a portion of the recess 65 formed on the surface side of the carrier 5, and the surface of the second mounting portion 26 corresponds to the bottom surface of the recess 65 on the opposite side to the back surface 24. The length d1 between the surface of the first mounting portion 25 and the surface of the second mounting portion 26 in the Y direction corresponds to the depth of the recess 65. The surface of the first mounting portion 25 and the surface of the third mounting portion 27 are flat surfaces without any step difference.

[0055] The light receiving element 2 outputs a light absorption current proportional to the power of the received monitor light 17, that is, a monitor current Im, to the control circuit 20. The control circuit 20 generates an injection current Iop so that the output current output from the light receiving element 2, that is, the monitor current Im, becomes constant, and outputs the injection current Iop to the semiconductor laser 1. The control circuit 20 controls the injection current Iop of the semiconductor laser 1 so that the output current of the light receiving element 2 as the light receiver 12 becomes constant. The optical module 100 performs automatic light output control through the control circuit 20.

[0056] The metal bonding material 6 is, for example, a solder such as AuSn, SnAg, SnAgCu, etc. The resin bonding materials 7 and 8 are bonding materials whose main components are, for example, acrylic acid, epoxy resin, thiol, etc. The metal bonding material 6 does not produce thermal curing shrinkage, but the resin bonding materials 7 and 8 produce thermal curing shrinkage. If the resin bonding materials 7 and 8 are exposed to an ambient temperature higher than room temperature, thermal curing shrinkage occurs according to the exposure time to the ambient temperature higher than room temperature, and the thickness in the Y direction decreases as shown by arrows 21 and 22. Here, the ambient temperature is the temperature around and inside the optical module 100. The light receiving element 2 moves to the surface side of the third mounting portion 27 by the thermal curing shrinkage of the resin bonding material 7, and the lens 3 moves to the surface side of the second mounting portion 26 by the thermal curing shrinkage of the resin bonding material 8. The light receiving element 2 and the lens 3 that have been exposed for a period of time are represented as the light receiving element 2a and the lens 3a shown by the dotted lines. As the exposure time elapses, the positional relationship of the semiconductor laser 1, the light receiving element 2 as the light receiving device 12, the lens 3, and the optical fiber 4 in the Y direction based on the back surface 24 of the carrier 5 changes. Therefore, the optical coupling efficiency between the semiconductor laser 1 and the light receiving device 12, and the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 change.

[0057] The optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 with respect to the exposure time are respectively defined as the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic. The optical module 100 of the first embodiment determines the initial positions of the optical receiver 12 and the lens 3 based on the back surface 24 of the carrier 5 in such a manner that the change trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same by performing automatic light output control. Therefore, when an irreversible composite relative position shift caused by a high temperature environment occurs between the semiconductor laser 1 and the optical fiber 4, the change of the light output can be suppressed. The composite relative position shift is the accumulated relative position shift between the semiconductor laser 1 and the optical fiber 4 including the position shift of the optical components when the optical components such as the lens 3 are interposed as described above. The initial positions of the optical receiver 12 and the lens 3 based on the back surface 24 of the carrier 5 are the respective positions when the exposure time of the optical module 100 in the high temperature environment is 0, and are the positions when the optical module 100 is manufactured. The initial positions of the semiconductor laser 1 and the distal end of the optical fiber 4 based on the back surface 24 of the carrier 5 are also the positions when the exposure time of the optical module 100 to the high temperature environment is 0, and are the positions when the optical module 100 is manufactured. This will be described in detail below.

[0058] exist Figure 1 , an example of the optical module 100 is shown in which the variation trend of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic is a decreasing trend, that is, the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic decrease over time. Figure 1 The optical module 100 of the first embodiment shown determines the initial positions of the semiconductor laser 1, the end of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 in such a manner that the changing trends of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic generated with the passage of exposure time become the same, for example, in such a manner that the changing trends become the same in a decreasing trend (first light coupling efficiency setting condition). Figure 2 to Figure 5 , the optical coupling efficiency between the semiconductor laser 1 and the light receiver 12 will be described.

[0059] The monitoring light 17 is emitted from the area on the second end face 72 side of the active layer 31 of the semiconductor laser 1, namely, the emission portion 39. The monitoring light 17 is received by the light receiving portion 32 of the light receiving element 2. As mentioned above, even when an optical module for general optical communication is exposed to a high temperature environment of 75 to 95°C for a reference time of about 2000 hours, the variation of the optical output is required to fall within ±0.5dB. The variation of the optical output within ±0.5dB becomes the standard of the reliability of the optical module 100. Therefore, in Figure 5FIG. 2 shows an example of the optical coupling efficiency characteristics of the semiconductor laser 1 and the light receiving element 2 when the reference time t1 is set to 2000 hours. Figure 6 An example of optical coupling efficiency characteristics of semiconductor laser 1 and optical fiber 4 is shown when reference time t1 is 2000 hours. The horizontal axis is exposure time, i.e., time of exposure to an ambient temperature higher than room temperature, and the vertical axis is optical coupling efficiency. Figure 5 The optical coupling efficiency characteristic 41 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiver 12 and the exposure time. The optical coupling efficiency characteristic 41 decreases as the exposure time passes, and is a characteristic whose changing trend is a decreasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e1 and e2, respectively.

[0060] exist Figure 2 The Y-direction positions of the semiconductor laser 1 and the light receiving element 2 are shown when the exposure time is 0, i.e., at the initial stage. Figure 4 FIG. 3 shows a beam cross section 34 of the monitor light 17 at the light receiving surface 37 in this case. Figure 3 The Y-direction positions of the semiconductor laser 1 and the light receiving element 2 are shown when the exposure time is longer than t1, that is, after the reference time has passed. Figure 4 The beam cross section 34a of the monitoring light 17 at the light receiving surface 37 in this case is shown. The light receiving element after the reference time has passed is marked with the reference symbol 2a. When the light receiving surface 37 in the range from the light receiving end 35a on the positive side of the Y direction of the light receiving portion 32 to the light receiving end 35b on the negative side of the Y direction of the light receiving portion 32 receives the monitoring light 17, the light receiving element 2 generates a monitoring current Im. The monitoring current Im increases or decreases according to the increase or decrease in the area of ​​the beam cross section of the monitoring light 17 incident on the light receiving surface 37, that is, the beam cross-sectional area. The area of ​​the beam cross section is appropriately expressed as the beam cross-sectional area. In Figure 4 In the figure, the beam cross sections 34 and 34a include the central axis 33 of the light receiving part, which is located on the side of the light receiving part end 35a on the positive side of the Y direction. As the exposure time passes, the resin bonding material 7 that fixes the light receiving element 2 and the carrier 5 undergoes thermal curing and shrinkage, and the light receiving element 2 moves to the negative side of the Y direction, thereby the monitoring light 17 moves to the positive side of the Y direction in the light receiving surface 37 of the light receiving element 2. Since the area of ​​the beam cross section 34 at the light receiving surface 37 is larger than the area of ​​the beam cross section 34a at the light receiving surface 37, as the exposure time passes, the light receiving area of ​​the monitoring light 17 received by the light receiving surface 37 decreases, so the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 decreases as the exposure time passes. Therefore, the monitoring current Im of the light receiving element 2 decreases as the exposure time passes.

[0061] Next, the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is described. The optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is the highest when the outgoing light 1 is incident along the central axis 15 of the optical fiber 4, and decreases when the angle between the outgoing light 16 and the central axis 15 becomes larger, and also decreases when the central axis of the beam of the outgoing light 16 is away from the central axis 15 of the optical fiber 4. Figure 1 The example in which the outgoing light 16 at the initial stage passes through the lens center axis of the lens 3 and is incident on the center axis 15 of the optical fiber 4 when the exposure time is 0, i.e., when the exposure time is longer than t1, i.e., after the reference time has passed, the outgoing light 16 passes through a position on the positive side in the Y direction than the lens center axis of the lens 3 and is incident from the center axis 15 of the optical fiber 4 to the negative side in the Y direction. The outgoing light after the reference time has passed and the lens are marked with reference numerals 16a and 3a, respectively.

[0062] Figure 6 The optical coupling efficiency characteristic 42 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 and the exposure time. The optical coupling efficiency characteristic 42 decreases as the exposure time passes, and is a characteristic whose changing trend is a decreasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e3 and e4, respectively.

[0063] exist Figure 1 , an example is shown in which the thickness of the resin bonding materials 7 and 8 in the Y direction is the same. In this case, the amount of thermal curing shrinkage of the resin bonding materials 7 and 8 as the exposure time passes is the same, and although it depends on the composition of the resin, it is, for example, 0.3 to 0.4 μm. Since the thickness of the resin bonding materials 7 and 8 in the Y direction is the same, the movement distance of the light receiving element 2 and the lens 3 to the negative side in the Y direction as the exposure time passes is the same. In the optical module 100 of embodiment 1, the positions of the semiconductor laser 1 and the terminal ends of the optical fiber 4 in the Y direction with respect to the back side 24 of the carrier 5 are fixed. In addition, the optical module 100 of embodiment 1 determines the initial positions of the light receiver 12 and the lens 3 with respect to the back side 24 of the carrier 5 in a manner that makes the changing trends of the first optical coupling efficiency characteristics and the second optical coupling efficiency characteristics the same, for example, in a manner that makes the changing trends in a decreasing trend the same. In Figure 4 , an example is shown in which the optical coupling efficiency between the semiconductor laser 1 and the optical receiver 12 is not maximized at the initial stage, but the initial position of the optical receiver 12 may be set so as to maximize the optical coupling efficiency between the semiconductor laser 1 and the optical receiver 12. In this case, the initial position of the optical receiver 12 may be determined so as to make the beam cross section 34 of the monitor light 17 coincide with the light receiving portion end 35a on the positive side in the Y direction of the light receiving surface 37. The initial position of the lens 3 may be determined so as to maximize or approximately maximize the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4, for example. Figure 4The beam cross section 34 of the monitor light 17 shown is an example in which the optical coupling efficiency is substantially the maximum, for example, an example in which the optical coupling efficiency is 95%.

[0064] The optical module 100 of the first embodiment determines the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 so that the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic generated with the passage of exposure time become the same, for example, so that the change trends become the same with a decreasing trend. Therefore, when the automatic light output control is performed on the semiconductor laser 1, in order to keep the monitoring current Im at a predetermined setting value, the control circuit 20 increases the injection current Iop of the semiconductor laser 1 with the passage of exposure time, that is, the injection current Iop increases with time. As a result, the optical module 100 of the first embodiment increases the light amount of the output light 16, that is, the optical power, even if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 decreases with the passage of exposure time, and thus can suppress the decrease in the light amount of the output light 16 introduced into the optical fiber 4, that is, the introduced optical power. In addition, the light amount of the output light 16 introduced into the optical fiber 4 is the light output of the optical module 100 used in optical communication. Therefore, the optical module 100 of the first embodiment can suppress the variation of the light output even if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 changes due to the composite relative positional deviation of the semiconductor laser 1 and the optical fiber 4 as the exposure time elapses.

[0065] In addition, although an example has been described in which the thickness of the resin bonding materials 7 and 8 in the Y direction is the same and the amount of thermal curing shrinkage generated with the exposure time is the same, it is not limited to this. In the optical module 100, since automatic light output control is performed, in order to extend the period of controllable period extended by automatic light output control, that is, the period during which the variation of light output can be suppressed, it is preferred that the end period of thermal curing shrinkage of the resin bonding material 7 used to fix the light receiving element 2 is later than the end period of thermal curing shrinkage of the resin bonding material 8 used to fix the lens 3. The period during which the variation of light output can be suppressed can also be referred to as the product life. In addition, in Figure 5 , Figure 6 , an example in which the thermal curing shrinkage of the resin bonding materials 7 and 8 is not completed is shown.

[0066] As described above, the optical module 100 of the first embodiment is an optical module that transmits the output light 16 emitted by the semiconductor laser 1 using the optical fiber 4. The optical module 100 of the first embodiment includes: the semiconductor laser 1 and the optical fiber 4; the optical receiver 12 that receives the monitoring light 17 emitted from the end face (the second end face 72) opposite to the output end face (the first end face 71) that emits the output light 16; the lens 3 that focuses the output light 16; the carrier 5 that carries the semiconductor laser 1, the optical receiver 12, and the lens 3; and the control circuit 20 that controls the injection current Iop of the semiconductor laser 1 so that the output current (monitoring current Im) of the optical receiver 12 becomes constant. The semiconductor laser 1 is fixed to the carrier 5 by the metal bonding material 6, at least a part of the light receiver 12 and the lens 3 are fixed to the carrier 5 by the first resin bonding material (resin bonding material 7) and the second resin bonding material (resin bonding material 8) respectively, which produce thermal curing shrinkage, and the terminal part of the optical fiber 4 for introducing the output light 16 is fixed with reference to the back side 24 of the carrier 5 on the opposite side of the surface of the mounting part (first mounting part 25, third mounting part 27, second mounting part 26) on which the semiconductor laser 1, the light receiver 12 and the lens 3 are mounted. The optical coupling efficiency between the semiconductor laser 1 and the optical receiver 12 and the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 with respect to the exposure time of the optical module 100 to the ambient temperature higher than the room temperature are respectively defined as the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic, and the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the optical receiver 12, and the lens 3 when the exposure time of the optical module is 0 with reference to the back surface 24 of the carrier 5 are determined so that the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same. The optical module 100 of the first embodiment has this structure, and the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the optical receiver 12 with reference to the back surface 24 of the carrier 5 are determined so that the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic with the passage of the exposure time become the same. Therefore, when an irreversible composite relative positional shift occurs between the semiconductor laser 1 and the optical fiber 4 due to the high temperature environment, the fluctuation of the optical output can be suppressed.

[0067] Implementation Method 2

[0068] Figure 7 This is a diagram showing a first example of an optical module according to the second embodiment. Figure 8 Yes means Figure 7 Figure 1 shows the initial positions of the semiconductor laser and the light receiving element. Fig. 9 Yes means Figure 7 A diagram showing the positions of a semiconductor laser and a light-receiving element after a reference time has passed. Fig.10 Yes means Figure 7A diagram of the monitor light at the light receiving surface of the light receiving element. Fig.11 is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element involved in the second embodiment, Fig.12 This is a diagram showing a first example of optical coupling efficiency characteristics between a semiconductor laser and an optical fiber according to the second embodiment. Fig.13 is a diagram showing a second example of the optical coupling efficiency characteristics of the semiconductor laser and the optical fiber involved in the second embodiment, Fig.14 This is a diagram showing a third example of the optical coupling efficiency characteristics between the semiconductor laser and the optical fiber according to the second embodiment. Fig.15 is a diagram showing a second example of an optical module according to Embodiment 2. Fig.16 Yes means Fig.15 The optical module 100 of the second embodiment is different from the optical module 100 of the first embodiment in that the initial positions of the semiconductor laser 1, the end of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 are determined in such a manner that the change trends of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic generated with the passage of exposure time become the same, for example, in such a manner that the change trends become the same in an increasing trend within a certain period from the initial. The parts different from the optical module 100 of the first embodiment will be mainly described.

[0069] exist Figure 7, an example of an optical module 100 is shown in which the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic have an increasing trend within a certain period from the initial stage, that is, the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic increase with time within a certain period from the initial stage. In order to increase the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic generated with the passage of exposure time with time within a certain period from the initial stage (second optical coupling efficiency setting condition), the initial positions of the semiconductor laser 1, the terminal portion of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 are determined as follows. As described in the first embodiment, when the exposure time has passed, the resin bonding material 8 shrinks due to thermal curing, thereby the position of the lens 3 moves to the negative side of the Y direction (-Y direction), and the output light 16 is also inclined to the negative side of the Y direction to become the output light 16a. Therefore, if the position of the optical fiber 4 is shifted, for example, from the position where the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 is maximum or approximately maximum to the negative side in the Y direction, the characteristic of the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 relative to the exposure time, that is, the second optical coupling efficiency characteristic, can be increased over time in a certain period from the initial stage. Similarly, after the exposure time has passed, the resin bonding material 7 undergoes thermal curing shrinkage, thereby the position of the light receiving element 2 as the light receiving device 12 moves to the negative side in the Y direction. Therefore, if the initial position of the light receiving element 2 as the light receiving device 12 is shifted, for example, from the position where the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 is maximum or approximately maximum to the positive side in the Y direction (+Y direction), the characteristic of the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 relative to the exposure time, that is, the first optical coupling efficiency characteristic, can be increased over time in a certain period from the initial stage.

[0070] Figure 7 The first example of the optical module 100 of the second embodiment shown in FIG. Figure 1 In the optical module 100 of the first embodiment shown, the position of the optical fiber 4 is offset to the negative side in the Y direction, and the initial position of the light receiving element 2 is offset to the positive side in the Y direction. Figure 7 The first example of the optical module 100 of the second embodiment shown in FIG. Figure 1 In the optical module 100 of the first embodiment shown, the length d1 of the surface of the first mounting portion 25 and the surface of the second mounting portion 26 in the Y direction corresponding to the depth of the recess 65 of the carrier 5 is increased, and the thickness of the resin bonding materials 7 and 8 is increased. Figure 7 The first example of the optical module 100 of the second embodiment achieves the second optical coupling efficiency setting condition while using the resin bonding materials 7 and 8 of the same thickness. First, the positions of the semiconductor laser 1 and the light receiver 12 and the optical coupling efficiency of the semiconductor laser 1 and the light receiver 12 are described.

[0071] exist Figure 8 The Y-direction positions of the semiconductor laser 1 and the light receiving element 2 are shown when the exposure time is 0, i.e., at the initial stage. Fig.10 FIG. 3 shows a beam cross section 34 of the monitor light 17 at the light receiving surface 37 in this case. Fig. 9 The Y-direction positions of the semiconductor laser 1 and the light receiving element 2 are shown when the exposure time is longer than t1, that is, after the reference time has passed. Fig.10 FIG. 3 shows a beam cross section 34a of the monitoring light 17 at the light receiving surface 37 in this case. The light receiving element after the reference time has passed is denoted by reference symbol 2a, and the light receiving portion 32 on the light receiving surface 37 side at the initial time is indicated by a dotted line and denoted by reference symbol 36. The length of the initial position of the light receiving element 2 shifted to the positive side in the Y direction is Fig. 9 The offset length Lm is shown. Fig.10 In the figure, the beam cross sections 34 and 34a include the central axis 33 of the light receiving part and are located on the side of the light receiving part end 35b on the negative side of the Y direction. As the exposure time passes, the resin bonding material 7 that fixes the light receiving element 2 and the carrier 5 undergoes thermal curing and shrinkage, and the light receiving element 2 moves to the negative side of the Y direction, thereby the monitoring light 17 moves to the positive side of the Y direction in the light receiving surface 37 of the light receiving element 2. Since the area of ​​the beam cross section 34 in the light receiving surface 37 is smaller than the area of ​​the beam cross section 34a in the light receiving surface 37, the light receiving area of ​​the monitoring light 17 received by the light receiving surface 37 increases as the exposure time passes, so the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 increases as the exposure time passes. Therefore, the monitoring current Im of the light receiving element 2 increases as the exposure time passes.

[0072] Fig.11 The optical coupling efficiency characteristic 43 shown represents the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 12 and the exposure time. The horizontal axis is the exposure time, i.e., the exposure time, and the vertical axis is the optical coupling efficiency. The optical coupling efficiency characteristic 43 increases with the exposure time, and is a characteristic whose change trend is an increasing trend. The optical coupling efficiencies when the exposure times are 0 and t1 are e5 and e6, respectively. The optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 is appropriately expressed as the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2, and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 is appropriately expressed as the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4.

[0073] Next, the positions of the lens 3 and the optical fiber 4, and the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 are described. Figure 7The example is shown in which the outgoing light 16 at the initial stage passes through the lens center axis of the lens 3 and enters the center axis 15 of the optical fiber 4 toward the positive side in the Y direction when the exposure time is 0, and the outgoing light 16 after the reference time has passed passes through a position closer to the positive side in the Y direction than the lens center axis of the lens 3 and enters the center axis 15 of the optical fiber 4 when the exposure time is greater than t1, that is, the outgoing light 16 after the reference time has passed is marked with reference numerals 16a and 3a, respectively, and a portion of the terminal end of the optical fiber 4 at the initial stage is indicated by a dotted line and marked with reference numeral 4s. The length of the initial position of the terminal end of the optical fiber 4 offset to the negative side in the Y direction is Figure 7 The offset length Lf is shown.

[0074] Fig.12 The optical coupling efficiency characteristic 44 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 and the exposure time. The horizontal axis is the exposure time, which is the time of exposure to an ambient temperature higher than room temperature, and the vertical axis is the optical coupling efficiency. The optical coupling efficiency characteristic 44 increases with the exposure time, and is a characteristic whose changing trend is an increasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e7 and e8, respectively.

[0075] Fig.12 The optical coupling efficiency characteristic 44 shown is the first example of the optical coupling efficiency characteristic of the semiconductor laser 1 and the optical fiber 4, and is an example in which the increasing trend continues until the reference time t1. However, the optical coupling efficiency characteristic of the semiconductor laser 1 and the optical fiber 4 is not limited to this. When the optical coupling efficiency characteristic reaches a peak halfway to the reference time t1, the change may stop and become constant. Fig.13 The optical coupling efficiency characteristic 45a shown is a second example of the optical coupling efficiency characteristic of the semiconductor laser 1 and the optical fiber 4, in which the increasing trend continues until the exposure time ta and the optical coupling efficiency reaches e8, then reaches the maximum optical coupling efficiency eh at the exposure time tp, and when the exposure time is the reference time t1, the optical coupling efficiency becomes e9 which is lower than e8. Fig.14 The optical coupling efficiency characteristic 45b shown is a third example of the optical coupling efficiency characteristic of the semiconductor laser 1 and the optical fiber 4, in which the optical coupling efficiency reaches e8 at the exposure time ta, the increasing trend continues until the exposure time tb and the optical coupling efficiency reaches e10, and then the optical coupling efficiency continues to be e10 until the exposure time reaches the reference time t1. Fig.13 , Fig.14 In the figure, the light coupling efficiency when the exposure time is 0 is e7.

[0076] Fig.13The optical coupling efficiency characteristic 45a having a peak is an optical coupling efficiency characteristic produced when the resin bonding material 8 undergoes thermal curing shrinkage even when the exposure time becomes the reference time t1, and the outgoing light 16a is incident on a position on the negative side of the central axis 15 of the optical fiber 4 in the Y direction. Fig.14 The optical coupling efficiency characteristic 45b shown is an example in which the exposure time becomes tb and the thermal curing shrinkage of the resin bonding material 8 is completed. In this case, the optical module 100 of the second embodiment performs automatic light output control, and determines the initial positions of the light receiving element 2 and the lens 3 as the light receiving device 12 that move to the surface side of the carrier 5 with the passage of exposure time, with the back surface 24 of the carrier 5 as a reference, so that the change trends of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic become the same within a certain period from the beginning. Therefore, when an irreversible composite relative position shift occurs between the semiconductor laser 1 and the optical fiber 4 due to a high temperature environment, the change of the light output can be suppressed.

[0077] Similarly, the optical coupling efficiency characteristics of the semiconductor laser 1 and the light receiver 12 may also stop changing and become constant when the optical coupling efficiency characteristics reach a peak value halfway through the reference time t1. Fig.10 The beam cross-sectional area of ​​the monitoring light 17 shown in FIG. 1 becomes larger. Initially, the monitoring light 17 includes the light receiving portion end 35b of the light receiving surface 37. When the exposure time becomes the reference time t1, the monitoring light 17 includes the light receiving portion end 35a of the light receiving surface 37. The change ends and becomes constant when the beam cross-sectional area of ​​the monitoring light 17 at the light receiving surface 37 becomes t2 when the exposure time becomes t3. Fig.10 The area of ​​the beam cross section 34a is the area of ​​the beam cross section 34a, and the thermal curing shrinkage of the resin bonding material 7 is completed when the beam cross section area completely enters the light receiving surface 37. In this case, since the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 and the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 change in the same manner as the exposure time passes, the change trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic change in the same manner. Therefore, the optical module 100 of the second embodiment performs automatic light output control, and determines the initial positions of the light receiving element 2 and the lens 3 as the light receiving device 12 that move to the surface side of the carrier 5 as the exposure time passes, with the back side 24 of the carrier 5 as the reference, so that the irreversible composite relative position shift caused by the high temperature environment occurs between the semiconductor laser 1 and the optical fiber 4. , It is possible to suppress the change of light output.

[0078] Figure 7 The first example of the optical module 100 of the second embodiment shown in the figure is an example in which the initial position of the optical fiber 4 is shifted to the negative side in the Y direction, but it may also be as follows. Fig.15 In this way, instead of shifting the optical fiber 4, the initial position of the lens 3 is shifted to the positive side in the Y direction. Fig.15 The second example of the optical module 100 of the second embodiment shown in FIG. Figure 1 In the optical module 100 of the first embodiment shown, the position of the lens 3 is shifted toward the positive side in the Y direction, and the initial position of the light receiving element 2 is shifted toward the positive side in the Y direction. Fig.15 The second example of the optical module 100 of the second embodiment shown in FIG. Figure 1 In the optical module 100 of the first embodiment shown, the length d1 of the surface of the first mounting portion 25 and the surface of the second mounting portion 26 in the Y direction corresponding to the depth of the recess 65 of the carrier 5 is shortened, and the thickness of the resin bonding materials 7 and 8 is increased. Fig.15 The second example of the optical module 100 of the second embodiment shown realizes the second optical coupling efficiency setting condition while using the resin bonding materials 7 and 8 having the same thickness.

[0079] The positions of the semiconductor laser 1 and the light receiver 12, the optical coupling efficiency of the semiconductor laser 1 and the light receiver 12 and Figure 7 The positions of the lens 3 and the optical fiber 4 and the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 are described below. Fig.16 The example in which, for example, when the exposure time is 0, i.e., the initial emitted light 16 passes through a position closer to the negative side in the Y direction than the lens center axis 13 of the lens 3 and is incident from the center axis 15 of the optical fiber 4 to the positive side in the Y direction is shown, and when the exposure time is longer than t1, i.e., after the reference time has passed, the emitted light 16 passes through the lens center axis 13 of the lens 3 and is incident on the center axis 15 of the optical fiber 4. The emitted light after the reference time has passed, the lens, and the lens center axis are marked with reference numerals 16a, 3a, and 13a, respectively. The length of the initial position of the lens 3 shifted to the positive side in the Y direction is Fig.16 The optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is Figure 7 The first example of the optical module 100 according to the second embodiment shown is the same.

[0080] The optical module 100 of the second embodiment determines the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 so that the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic generated with the passage of exposure time become the same, for example, so that the variation trends become the same with an increasing trend within a certain period from the initial stage. Therefore, when the automatic light output control is performed on the semiconductor laser 1, in order to keep the monitoring current Im at a predetermined set value, the control circuit 20 reduces the injection current Iop of the semiconductor laser 1 with the passage of exposure time, that is, the injection current Iop decreases with time. Therefore, even if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 increases with the passage of exposure time, the optical module 100 of the second embodiment suppresses the increase in the light amount, that is, the optical power, of the output light 16, and thus can suppress the increase in the light amount, that is, the optical power, of the output light 16 introduced into the optical fiber 4. Therefore, the optical module 100 of the second embodiment can suppress the variation of the light output even if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 changes due to the composite relative positional deviation of the semiconductor laser 1 and the optical fiber 4 caused by the passage of exposure time.

[0081] Implementation 3

[0082] Fig.17 1 is a diagram showing a first example of an optical module according to Embodiment 3. Fig.18 Yes means Fig.17 A diagram showing the optical coupling efficiency characteristics of a semiconductor laser and a light-receiving element. Fig.19 is a diagram showing a second example of an optical module according to Embodiment 3. Fig. 20 Yes means Fig.19 1 and 2. The optical module 100 of the third embodiment is different from the optical modules 100 of the first and second embodiments in that the amount of thermal curing shrinkage of the resin bonding material 7 generated with the passage of exposure time is greater than the amount of thermal curing shrinkage of the resin bonding material 8. The following mainly describes the parts that are different from the optical modules 100 of the first and second embodiments.

[0083] Generally, single-mode optical fiber is used for optical fiber 4, and the mode field diameter (full width) is about 10 μm in the case of light with a wavelength of 1.5 μm. On the other hand, the area of ​​the light receiving surface or the light receiving diameter of the light receiving element 2 is wider than the mode field diameter of the optical fiber 4 in most cases. In addition, although the output light 16 of the semiconductor laser 1 introduced into the optical fiber 4 is focused by the lens 3, the monitoring light 17 of the semiconductor laser 1 introduced into the light receiving element 2 does not pass through the lens, so the beam diameter is wider than the output light 16 focused by the lens 3. The beam cross section of the monitoring light 17 at the light receiving surface 37 of the light receiving element 2 is larger than the beam cross section of the output light 16 at the end face of the optical fiber 4 on the lens 3 side. When the monitoring light 17 and the outgoing light 16 move the same distance, the change in the beam cross-sectional area of ​​the monitoring light 17 at the light receiving surface 37 when passing through the light receiving end 35a or the light receiving end 35b is smaller than the change in the beam cross-sectional area of ​​the outgoing light 16 after being focused at the end face of the optical fiber 4. Therefore, the change in the optical coupling efficiency in the light receiving element 2 is smaller than the change in the optical coupling efficiency in the optical fiber 4.

[0084] When the automatic light output control is performed by the control circuit 20, the larger the change in the light coupling efficiency in the light receiving element 2, the larger the correction amount of the light output of the optical module 100. For this reason, in the third embodiment, the correction amount of the light output when the automatic light output control is performed is increased by making the amount of thermal curing shrinkage of the resin bonding material 7 that fixes the light receiving element 2 larger than the resin bonding material 8 that fixes the lens 3 as the exposure time passes. The larger change in the light coupling efficiency in the light receiving element 2 means that the detection sensitivity of the composite relative position shift of the semiconductor laser 1 and the optical fiber 4 generated as the exposure time passes is improved. The larger correction amount of the light output at the same time means that the correction speed of the light coupling efficiency accompanied by the composite relative position shift of the semiconductor laser 1 and the optical fiber 4 generated as the exposure time passes is large. Therefore, the optical module 100 of the third embodiment can suppress the change of the light output with a smaller variation range than the optical modules 100 of the first and second embodiments. In order to make the amount of thermal curing shrinkage of the resin bonding material 7 generated as the exposure time passes larger than the amount of thermal curing shrinkage of the resin bonding material 8, it is sufficient to proceed as follows. For example, as a first resin bonding material thickness setting method, when resin bonding materials 7 and 8 are made of the same material, the thickness of resin bonding material 7 can be made thicker than that of resin bonding material 8. In this case, the thermal curing shrinkage of resin bonding material 7, which has a larger volume, is greater than that of resin bonding material 8.

[0085] In addition, as a second resin bonding material thickness setting method, when the amount of thermal curing shrinkage of the resin bonding materials 7 and 8 has the property of being saturated as the exposure time passes, it is sufficient to only allow the resin bonding material 8 to be thermally cured and shrunk in advance. Even in this case, when the exposure time of the optical module 100 is 0, the thickness of the resin bonding material 7 is thicker than the thickness of the resin bonding material 8. For the second resin bonding material thickness setting method, for example, in the manufacturing process of the optical module 100, only the lens 3 is fixed by the resin bonding material 8 without fixing the light receiving element 2, and the carrier 5 carrying the semiconductor laser 1 and the lens 3 in the middle of manufacturing is exposed to a high temperature environment. Thus, only the thermal curing shrinkage of the resin bonding material 8 is performed in advance. Thereafter, the light receiving element 2 is fixed to the carrier 5 using the resin bonding material 7. In this case, the thickness of the resin bonding material 7 can be made thicker than the thickness of the resin bonding material 8 by the difference in the progress of the thermal curing shrinkage of the resin bonding materials 7 and the resin bonding materials 8.

[0086] As a third method for setting the thickness of the resin bonding material, different materials may be used for the resin bonding material 7 and the resin bonding material 8 to provide a difference in the amount of thermal curing shrinkage.

[0087] Fig.17 The first example of the optical module 100 of the third embodiment shown in the figure is an example in which the resin bonding materials 7 and 8 having different thicknesses are applied to the optical module 100 of the first embodiment. Figure 1 The difference of the optical module 100 of the embodiment 1 shown is that the thickness of the resin bonding material 7 in the Y direction is greater than the thickness of the resin bonding material 8 in the Y direction, and the light receiving element 2 is fixed to the surface of the third mounting portion 27, and the surface of the third mounting portion 27 is equivalent to the bottom surface of the recess 66 provided on the carrier 5 on the opposite side of the back side 24. Fig.19 The second example of the optical module 100 according to the third embodiment shown in the figure is an example in which the resin bonding materials 7 and 8 having different thicknesses are applied to the first example of the optical module 100 according to the second embodiment. Figure 7 The difference of the first example of the optical module 100 of the second embodiment shown is that the thickness of the resin bonding material 7 in the Y direction is greater than the thickness of the resin bonding material 8 in the Y direction, and the light receiving element 2 is fixed to the surface of the third mounting portion 27, and the surface of the third mounting portion 27 is equivalent to the bottom surface of the recess 66 provided in the carrier 5 on the opposite side of the back side 24.

[0088] First of all, Fig.17The first example of the optical module 100 of the third embodiment shown in FIG. 3 is described. The third mounting portion 27 is a portion of the recess 66 formed on the surface side of the carrier 5, and the surface of the third mounting portion 27 corresponds to the bottom surface of the recess 66 on the opposite side to the back surface 24. The length d2 in the Y direction between the surface of the first mounting portion 25 and the surface of the third mounting portion 27 corresponds to the depth of the recess 66. Fig.18 The optical coupling efficiency characteristic 41a shown represents the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 as the light receiving device 12 and the exposure time. Among them, the characteristic of the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 as the light receiving device 12 in the optical module 100 of embodiment 1, that is, the optical coupling efficiency characteristic 41 is represented by a dotted line. The horizontal axis is the exposure time, that is, the exposure time, and the vertical axis is the optical coupling efficiency. The optical coupling efficiency characteristic 41a decreases with the exposure time, and is a characteristic whose change trend is a decreasing trend. The decreasing slope of the change of the optical coupling efficiency characteristic 41a is steeper than that of the optical coupling efficiency characteristic 41. The optical coupling efficiency when the exposure time is 0 is e1, and the optical coupling efficiency when the exposure time is t1 is e2a, which is smaller than e2.

[0089] Next, explain Fig.19 The third mounting portion 27 for fixing the light receiving element 2, the recess 66 and the Fig.17 The first example of the optical module 100 according to the third embodiment shown is the same. Fig. 20 The optical coupling efficiency characteristic 43a shown represents the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 as the light receiving device 12 and the exposure time. Among them, the characteristic of the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 as the light receiving device 12 in the optical module 100 of Embodiment 2, that is, the optical coupling efficiency characteristic 43 is represented by a dotted line. The horizontal axis is the exposure time, that is, the exposure time, and the vertical axis is the optical coupling efficiency. The optical coupling efficiency characteristic 43a increases with the exposure time, and is a characteristic whose change trend is an increasing trend. The increase slope of the change of the optical coupling efficiency characteristic 43a is steeper than that of the optical coupling efficiency characteristic 43. The optical coupling efficiency when the exposure time is 0 is e5, and the optical coupling efficiency when the exposure time is t1 is e6a, which is smaller than e6. In addition, as Fig.13 , Fig.14 As shown, when the optical coupling efficiency characteristic 43 a reaches a peak value halfway before reaching the reference time t1 , the optical coupling efficiency characteristic 43 a may stop changing and become constant.

[0090] Implementation 4

[0091] Fig.21 It is a diagram showing an optical module according to a fourth embodiment. Fig. 22 Yes means Fig.21The diagram shows the position change of the light receiving element and the light receiving limit point of the monitoring light. Fig.23 1 is a diagram showing the position change of the light receiving limit point of the light receiving element and the monitoring light of the comparative example. The optical module 100 of the fourth embodiment is different from the optical module 100 of the first embodiment in that the monitoring light 17 is changed into the monitoring light 18 of the diffused light, and the monitoring light 18 is received by the planar light receiving element 30. The parts different from the optical module 100 of the first embodiment are mainly described.

[0092] The light receiving surface 37 of the light receiving element 30 is arranged at a position closer to the back surface 24 of the carrier 5 than the emission portion 39 of the monitor light 18, and does not intersect with the optical axis 40 of the monitor light 18. The semiconductor laser 1 of the fourth embodiment includes a spot size conversion portion 38 for enlarging the spot size of the laser light, for example, on the second end face 72 side of the active layer 31, and emits the monitor light 18 having a light spot size enlarged than that of the monitor light 17, that is, diffused light. Fig. 22 The diffused light boundaries 19a and 19b of the monitoring light 18 in the Y direction are also shown. The diffused light boundary 19a is the boundary on the positive side of the Y direction, and the diffused light boundary 19b is the boundary on the negative side of the Y direction. The solid line indicates the light receiving element 30 when the exposure time is 0. Fig. 22 , the light receiving element when the exposure time is greater than or equal to the reference time t1 is indicated by a dotted line and is marked with reference numeral 30a. The light receiving surface 37 of the light receiving element 30 is tilted at an angle θ relative to the Z-axis direction, and the light receiving surface 37 of the light receiving element 30 is configured to face the second end face 72 of the semiconductor laser 1. The angle θ is, for example, 0° to 30°.

[0093] When the exposure time is 0, the diffused light boundary 19b of the monitor light 18 passes through the light receiving limit point p1 on the semiconductor laser 1 side in the light receiving surface 37 of the light receiving element 30. When the exposure time is equal to or longer than the reference time t1, the diffused light boundary 19b of the monitor light 18 passes through the light receiving limit point p2 in the light receiving surface 37 of the light receiving element 30a which moves to the negative side in the Y direction due to the thermal curing shrinkage of the resin bonding material 7. Therefore, the area of ​​the beam cross section of the monitor light 18 received by the light receiving element 30a in the light receiving surface 37, i.e., the light receiving area, is smaller than the area of ​​the beam cross section of the monitor light 18 received by the light receiving element 30 in the light receiving surface 37, i.e., the light receiving area. The beam cross section area of ​​the monitor light 18 received by the light receiving element 30 decreases in accordance with the passage of the exposure time. The optical coupling efficiency change characteristics of the semiconductor laser 1 and the light receiver 12 become the same as those in the first embodiment.

[0094] The optical module 100 of the fourth embodiment determines the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiver 12 with respect to the back surface 24 of the carrier 5 in a manner that makes the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic generated with the passage of exposure time become the same, for example, in a manner that makes the changing trends become the same with a decreasing trend. Therefore, when automatic light output control is performed on the semiconductor laser 1, similarly to the optical module 100 of the first embodiment, when an irreversible composite relative position shift caused by a high temperature environment occurs between the semiconductor laser 1 and the optical fiber 4, the change of the light output can be suppressed.

[0095] In the optical module 100 of the fourth embodiment, the amount of change in optical coupling efficiency due to the thermal curing shrinkage of the resin bonding material 7 is greater than that of the comparative example in which the light receiving surface 37 is inclined at an angle θ with respect to the Y-axis direction. Fig.23 In the comparative example shown, when the exposure time is 0, the diffused light boundary 19b of the monitor light 18 passes through the light receiving limit point p3 of the light receiving surface 37 of the light receiving element 30. When the exposure time is equal to or longer than the reference time t1, the diffused light boundary 19b of the monitor light 18 passes through the light receiving limit point p4 in the light receiving surface 37 of the light receiving element 30a which moves to the negative side in the Y direction due to the thermal curing shrinkage of the resin bonding material 7, and the diffused light boundary 19a of the monitor light 18 passes through the upper limit in the Y direction of the light receiving surface 37. Therefore, the beam cross-sectional area of ​​the monitor light 18 received by the light receiving element 30a is only slightly smaller than the beam cross-sectional area of ​​the monitor light 18 received by the light receiving element 30, and hardly changes. In the optical module 100 of the fourth embodiment, since the amount of change in the beam cross-sectional area of ​​the monitor light 18 received by the light receiving element 30 according to the elapse of the exposure time can be made greater than that in the comparative example, the amount of change in the optical coupling efficiency can be made greater than that in the comparative example. The optical module 100 of Embodiment 4 can make the change in optical coupling efficiency greater than that of the comparative example, so the correction amount of optical output when automatic optical output control is performed can be greater than that of the comparative example. Therefore, the optical module 100 of Embodiment 4 can suppress the change in optical output with a smaller change range than that of the comparative example.

[0096] Implementation method 5

[0097] Fig.24 This is a diagram showing an optical module according to the fifth embodiment. Fig.25 Yes means Fig.24 The monitor light lens and the monitor light position change diagram, Fig.26 Yes means Fig.24 A diagram of the monitor light at the light receiving surface of the light receiving element. Fig. 27 is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element involved in the fifth embodiment. Fig.281 is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the optical fiber involved in Embodiment 5. The optical module 100 of Embodiment 5 is different from the optical module 100 of Embodiment 1 in that the light receiver 12 includes the light receiving element 2 and the lens 9. The lens 9 is a monitor light lens and focuses the monitor light 17. The parts different from the optical module 100 of Embodiment 1 will be mainly described.

[0098] The monitoring light 17 emitted from the second end face 72 of the semiconductor laser 1 is focused by the lens 9 and received by the light receiving element 2. The light receiving element 2 is fixed to the surface of the third mounting portion 27 of the carrier 5 by the metal bonding material 11 that does not produce thermal curing shrinkage. The lens 9 is fixed to the surface of the fourth mounting portion 28 of the carrier 5 by the resin bonding material 10 that produces thermal curing shrinkage. The metal bonding material 11 is, for example, a solder such as AuSn, SnAg, SnAgCu, etc., similarly to the metal bonding material 6. The resin bonding material 10 is, for example, a bonding material with acrylic acid, epoxy resin, thiol, etc. as the main component, similarly to the resin bonding material 8. The optical module 100 of embodiment 1 fixes the light receiving element 2 as the light receiver 12 on the surface of the third mounting portion 27 of the carrier 5 by the resin bonding material 7 that produces thermal curing shrinkage. In contrast, in the optical module 100 of the fifth embodiment, the light receiving element 2 as a part of the light receiving device 12 is fixed to the carrier 5 by the metal bonding material 11 which does not produce thermal curing shrinkage, and the lens 9 as a part of the light receiving device 12 is fixed to the carrier 5 by the resin bonding material 10 which produces thermal curing shrinkage. When the resin bonding material 10 is exposed to an ambient temperature higher than room temperature, it produces thermal curing shrinkage according to the exposure time to the ambient temperature higher than room temperature, and as shown by the arrow 23, the thickness in the Y direction decreases.

[0099] The resin bonding material 10 shrinks by thermal curing, so that the lens 9 moves to the surface side of the fourth mounting portion 28, and the resin bonding material 8 shrinks by thermal curing, so that the lens 3 moves to the surface side of the second mounting portion 26. The lens 9 and the lens 3 that have passed the exposure time are represented as the lens 9a and the lens 3a represented by the dotted line. As the exposure time passes, the positional relationship of the semiconductor laser 1, the light receiving element 2 constituting the light receiving device 12, and the lens 9, the lens 3, and the optical fiber 4 with respect to the back surface 24 of the carrier 5, that is, the positional relationship in the Y direction changes. Therefore, in the optical module 100 of the fifth embodiment, the optical coupling efficiency of the semiconductor laser 1 and the light receiving device 12, and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 change in the same manner as the optical module 100 of the first embodiment.

[0100] The second mounting portion 26, the first mounting portion 25, the fourth mounting portion 28, and the third mounting portion 27 are arranged from the side close to the optical fiber 4. The range from the dotted line 53a to the dotted line 53b is the second mounting portion 26, and the range from the dotted line 53b to the dotted line 53c is the first mounting portion 25. The range from the dotted line 53c to the dotted line 54a is the fourth mounting portion 28, and the range from the dotted line 54a to the dotted line 54b is the third mounting portion 27. The second mounting portion 26 is a portion of the recess 65 formed on the surface side of the carrier 5, and the surface of the second mounting portion 26 corresponds to the bottom surface of the recess 65 on the opposite side to the back surface 24. The length d1 of the surface of the first mounting portion 25 and the surface of the second mounting portion 26 in the Y direction corresponds to the depth of the recess 65. The surface of the first mounting portion 25, the surface of the fourth mounting portion 28, and the surface of the third mounting portion 27 are planes without a step difference.

[0101] As described above, the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 with respect to the exposure time are the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic, respectively. The optical module 100 of the fifth embodiment performs automatic light output control, and determines the initial positions of the lens 9 and the lens 3, which are part of the optical receiver 12 and move to the surface side of the carrier 5 with the passage of exposure time, with the back surface 24 of the carrier 5 as a reference, so that the change trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same. Therefore, when an irreversible composite relative position shift occurs between the semiconductor laser 1 and the optical fiber 4 due to a high temperature environment, the change of the light output can be suppressed.

[0102] exist Fig.24 , an example of the optical module 100 is shown in which the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic have a decreasing trend, that is, the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic decrease over time. Fig.24 In the optical module 100 of the fifth embodiment shown, the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, the light receiving element 2 constituting the light receiving device 12, and the lens 9 with respect to the back side 24 of the carrier 5 are determined in a manner that makes the changing trends of the first light coupling efficiency characteristics and the second light coupling efficiency characteristics generated with the passage of exposure time become the same, for example, in a manner that makes the changing trends become the same with a decreasing trend (the above-mentioned first light coupling efficiency setting condition).

[0103] The monitor light 17 emitted from the region on the second end face 72 side of the active layer 31 of the semiconductor laser 1, that is, the emission portion 39, is focused by the lens 9, and the focused monitor light 17 is received by the light receiving portion 32 of the light receiving element 2. Fig. 27 , Fig.28An example of the optical coupling efficiency characteristics of the semiconductor laser 1 and the light receiving element 2 of the light receiving device 12 when the reference time t1 is set to 2000 hours, and an example of the optical coupling efficiency characteristics of the semiconductor laser 1 and the optical fiber 4 when the reference time t1 is set to 2000 hours are shown. The horizontal axis is the exposure time, i.e., the exposure time, and the vertical axis is the optical coupling efficiency. Fig. 27 The optical coupling efficiency characteristic 46 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiver 12 and the exposure time. The optical coupling efficiency characteristic 46 decreases as the exposure time passes, and is a characteristic whose changing trend is a decreasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e11 and e12, respectively. Fig.28 The optical coupling efficiency characteristic 47 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 and the exposure time. The optical coupling efficiency characteristic 47 decreases as the exposure time passes, and is a characteristic whose changing trend is a decreasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e13 and e14, respectively.

[0104] The change in the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 related to the position of the semiconductor laser 1 and the optical fiber 4 is the same as in Embodiment 1 and will not be described again. The change in the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 related to the position of the semiconductor laser 1 and the optical receiver 12 will be described.

[0105] exist Fig.25 The Y-direction positions of the lens 9 and the light receiving element 2 are shown when the exposure time is 0, that is, at the initial time. Fig.26 FIG. 6 shows a beam cross section 61 of the focused monitor light 17 at the light receiving surface 37 in this case. Fig.25 The Y-direction positions of the lens 9a and the light receiving element 2 are shown when the exposure time is longer than t1, that is, after the reference time has passed. Fig.26 FIG. 6 shows a beam cross section 61a of the monitor light 17 after being focused on the light receiving surface 37 in this case. Since the monitor light 17 is focused, the monitor light 17 is Figure 4 In comparison, the beam cross-sectional area becomes smaller. Figure 24 to Figure 26 The example shown is that the monitor light 17 at the light receiving surface 37 moves to the negative side in the Y direction as the lens 9 moves to the negative side in the Y direction.

[0106] The optical coupling efficiency between the semiconductor laser 1 and the light receiver 12 changes according to the increase or decrease of the beam cross-sectional area of ​​the monitor light 17 incident on the light receiving surface 37, that is, the light receiving area. When the exposure time is 0, the monitor light 17 advances toward the negative side in the Z direction along the lens center axis 14 of the lens 9, and reaches, for example, a position of the beam cross section 61 in contact with the light receiving portion end 35b of the light receiving surface 37. When the exposure time is t1 or longer, the monitor light 17 passes through a position closer to the positive side in the Y direction than the lens center axis 14a of the lens 9a after the monitor light 17 moves toward the negative side in the Y direction, and thus the monitor light 17a that advances toward the negative side in the Y direction from the monitor light 17 is incident on the light receiving surface 37 of the light receiving element 2 of the light receiver 12. The beam cross section 61a of the monitor light 17a at the light receiving surface 37 moves toward the negative side in the Y direction so as to include the light receiving portion end 35b. The area of ​​the beam cross section 61 at the light receiving surface 37 is larger than the area of ​​the beam cross section 61a at the light receiving surface 37, and the light receiving area of ​​the received light decreases with the exposure time, so the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 decreases with the exposure time.

[0107] In the optical module 100 of the fifth embodiment, the monitor light 17 of the semiconductor laser 1 introduced into the light receiving element 2 can be focused by the lens 9, similarly to the outgoing light 16 of the semiconductor laser 1 introduced into the optical fiber 4. Therefore, the amount of change in the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 caused by the thermal curing shrinkage of the resin bonding material 10 is likely to be larger than that of the optical module 100 of the first embodiment in which the light receiver 12 does not include the lens 9. This is because if the area of ​​the beam cross section at the light receiving surface 37 is small, the proportion of the area away from the light receiving surface 37 becomes larger even if the moving distance in the Y direction is the same as that in the case where the area of ​​the beam cross section is large. Therefore, it is easy to design so that the amount of reduction in the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 caused by the passage of exposure time in a high temperature environment is equal to the amount of reduction in the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4.

[0108] When the optical module 100 of the fifth embodiment performs automatic light output control, the change in the light coupling efficiency in the light receiving element 2 is greater than that of the optical module 100 of the first embodiment, so the correction amount of the light output of the optical module 100 becomes larger. As described in the third embodiment, the optical module 100 of the fifth embodiment can improve the detection sensitivity of the composite relative position shift between the semiconductor laser 1 and the optical fiber 4 generated with the passage of exposure time, and can increase the correction speed of the light coupling efficiency associated with the composite relative position shift between the semiconductor laser 1 and the optical fiber 4 generated with the passage of exposure time, compared with the optical module 100 of the first embodiment. Therefore, the optical module 100 of the fifth embodiment can suppress the change of the light output with a smaller change range than the optical module 100 of the first embodiment.

[0109] For example, if the following conditions are met, the amount of change in the optical coupling efficiency in the light receiving element 2 can be sufficiently increased, and the amount of change in the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 can be designed to be equal to the amount of change in the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 and the amount of change in the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4. The first condition is that the beam diameter of the monitor light 17 irradiated to the light receiving element 2, that is, the diameter of the beam cross section 61, 61a, is the same as the beam diameter irradiated to the optical fiber 4. The second condition is that the size of the light receiving surface 37 of the light receiving portion 32 of the light receiving element 2 is the same as the size of the optical coupling portion of the optical fiber 4. In the case where the optical fiber 4 has a core and a cladding with different refractive indices, the size of the optical coupling portion is the size of the core. The optical module 100 of embodiment 5 is an example that satisfies the first condition.

[0110] In the optical module 100 of the fifth embodiment, since the semiconductor laser 1 and the light receiving element 2 are fixed to the carrier 5 by the metal bonding materials 6 and 11, it is difficult to fine-tune the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2. Therefore, the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 is set to, for example, the maximum by setting the thickness of the resin bonding material 10 of the lens 9. Fig.24 , an example is shown in which the thickness of the resin bonding material 8 in the Y direction is equal to the thickness of the resin bonding material 10 in the Y direction. In the case where the resin bonding material 8 of the lens 3 and the resin bonding material 10 of the lens 9 are made of the same material, if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is set in the same manner as the optical module 100 of the first embodiment, and the first condition or the second condition described above is satisfied, the decrease in the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 caused by the passage of exposure time in a high temperature environment can be made equal to the decrease in the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4.

[0111] The optical module 100 of the fifth embodiment fixes the semiconductor laser 1 and the light receiving element 2 to the carrier 5 at the same time by the metal bonding materials 6 and 11, and fixes the lens 3 and the lens 9 to the carrier 5 at the same time by the resin bonding materials 8 and 10, so compared with the optical module 100 of the first embodiment, the fixing time of the light receiving device 12 can be shortened. For the usual resin bonding materials, the fixing usually requires UV light irradiation for tens of seconds to several minutes, but if the fixing is made by solder, it can be completed within a few seconds. In addition, the optical module 100 of the fifth embodiment fixes the light receiving element 2 to the carrier 5 by the metal bonding material 11, so the heat dissipation of the light receiving element 2 can be improved compared with the optical module 100 of the first embodiment.

[0112] In addition, the optical module 100 of the fifth embodiment may also make the amount of thermal curing shrinkage of the resin bonding material 10 of the light receiver 12 generated with the passage of exposure time greater than the amount of thermal curing shrinkage of the resin bonding material 8 of the lens 3 as described in the third embodiment. In this case, the optical module 100 of the fifth embodiment makes the amount of thermal curing shrinkage of the resin bonding material 10 generated with the passage of exposure time greater than that of the resin bonding material 8, thereby increasing the correction amount of the light output when the automatic light output control is performed, and can suppress the change of the light output with a small change range.

[0113] As described above, the optical module 100 of the fifth embodiment is an optical module that transmits the output light 16 emitted by the semiconductor laser 1 using the optical fiber 4. The optical module 100 of the fifth embodiment includes: the semiconductor laser 1 and the optical fiber 4; the optical receiver 12 that receives the monitor light 17 emitted from the end face (the second end face 72) opposite to the output end face (the first end face 71) that emits the output light 16; the lens 3 that focuses the output light 16; the carrier 5 that carries the semiconductor laser 1, the optical receiver 12, and the lens 3; and the control circuit 20 that controls the injection current Iop of the semiconductor laser 1 so that the output current (monitor current Im) of the optical receiver 12 becomes constant. The optical receiver 12 includes another lens 9 that focuses the monitor light 17, and a light receiving element 2 that receives the monitor light 17 focused by the other lens 9. The semiconductor laser 1 is fixed to the carrier 5 by the metal bonding material 6, the light receiving element 2 is fixed to the carrier 5 by the metal bonding material 11, and the other lens 9 and the lens 3 which are at least a part of the light receiver 12 are fixed to the carrier 5 by the first resin bonding material (resin bonding material 10) and the second resin bonding material (resin bonding material 8) which produce thermal curing shrinkage, respectively. The terminal part of the introduced output light 16 in the optical fiber 4 is fixed with respect to the back side 24 of the carrier 5 which is opposite to the surface of the mounting part (first mounting part 25, third mounting part 27, fourth mounting part 28, second mounting part 26) on which the semiconductor laser 1, the light receiver 12 and the lens 3 are mounted. The optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 with respect to the exposure time of the optical module 100 to the ambient temperature higher than the room temperature are respectively defined as the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic, and the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the optical receiver 12, and the lens 3 when the exposure time of the optical module is 0 with reference to the back surface 24 of the carrier 5 are determined so that the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same. The optical module 100 of the fifth embodiment has this structure, and the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the optical receiver 12 with reference to the back surface 24 of the carrier 5 are determined so that the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic generated with the passage of the exposure time become the same. Therefore, when an irreversible composite relative positional shift occurs between the semiconductor laser 1 and the optical fiber 4 due to the high temperature environment, the fluctuation of the optical output can be suppressed.

[0114] Implementation 6

[0115] Fig.29 is a diagram showing a first example of an optical module according to Embodiment 6. Fig.30 Yes means Fig.29 FIG. 1 is a diagram of the main parts of the mounting section of the light receiver. Fig.31Yes means Fig.29 The monitor light lens and the monitor light position change diagram, Fig.32 Yes means Fig.29 A diagram of the monitor light at the light receiving surface of the light receiving element. Fig.33 is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the light receiving element involved in Embodiment 6, Fig.34 This is a diagram showing the optical coupling efficiency characteristics of the semiconductor laser and the optical fiber involved in the sixth embodiment. Fig.35 is a diagram showing a second example of an optical module according to Embodiment 6. Fig.36 Yes means Fig.35 FIG. 1 is a diagram of the main parts of the mounting section of the light receiver. Fig.37 Yes means Fig.35 A diagram showing a monitor light lens and a position change of the monitor light. Fig.38 is a diagram showing the main parts of a third example of an optical module according to Embodiment 6. Fig.39 Yes means Fig.38 A diagram showing a monitor light lens and a position change of the monitor light.

[0116] The optical module 100 of the sixth embodiment is different from the optical module 100 of the second embodiment in that the light receiver 12 includes the light receiving element 2 and the lens 9. The parts different from the optical module 100 of the second embodiment will be mainly described. Fig.29 The first example of the optical module 100 according to the sixth embodiment shown in FIG. Fig.35 The second example of the optical module 100 of the sixth embodiment shown is a light receiving device 12 including a light receiving element 2 and a lens 9 applied to Figure 7 The optical module 100 of the second embodiment shown in the figure is a first example. Fig.38 The third example of the optical module 100 of the sixth embodiment of the present invention is a Fig.35 The second example of the optical module 100 according to the sixth embodiment shown is an example in which the size of the lens 9 is changed so that the surface of the mounting portion of the semiconductor laser 1, the lens 9, and the light receiving element 2 is a flat surface without a step. Fig.29 The first example of optical module 100 according to the sixth embodiment is an example in which monitor light 17 initially traveling forward is received by light receiving element 2 , and monitor light 17 moves to the negative side in the Y direction and is received by light receiving element 2 as exposure time elapses. Fig.35 The second example of the optical module 100 according to the sixth embodiment shown in FIG. Fig.38 The third example of the optical module 100 of the sixth embodiment of the main part shown is an example in which the monitoring light 17 bent toward the positive side in the Y direction by the lens 9 is initially received by the light receiving element 2, and as the exposure time passes, the monitoring light 17 moves toward the negative side in the Y direction and is received by the light receiving element 2.

[0117] The optical module 100 of the sixth embodiment is similar to the optical module 100 of the second embodiment. The initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiver 12 are determined with respect to the back surface 24 of the carrier 5 in such a manner that the changing trends of the first optical coupling efficiency characteristics and the second optical coupling efficiency characteristics generated with the passage of exposure time become the same, for example, in such a manner that the changing trends become the same with an increasing trend within a certain period from the initial stage. Therefore, even if the composite relative position of the semiconductor laser 1 and the optical fiber 4 shifts with the passage of exposure time and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 changes, the variation of the light output can be suppressed.

[0118] The monitoring light 17 emitted from the second end face 72 of the semiconductor laser 1 is focused by the lens 9 and received by the light receiving element 2. The light receiving element 2 is fixed to the surface of the third mounting portion 27 of the carrier 5 by the metal bonding material 11 that does not produce thermal curing shrinkage. The lens 9 is fixed to the surface of the fourth mounting portion 28 of the carrier 5 by the resin bonding material 10 that produces thermal curing shrinkage. The metal bonding material 11 is, for example, a solder such as AuSn, SnAg, SnAgCu, etc., similarly to the metal bonding material 6. The resin bonding material 10 is, for example, a bonding material with acrylic acid, epoxy resin, thiol, etc. as the main component, similarly to the resin bonding material 8. The optical module 100 of the second embodiment fixes the light receiving element 2 as the light receiving device 12 on the surface of the third mounting portion 27 of the carrier 5 by the resin bonding material 7 that produces thermal curing shrinkage. In contrast, in the optical module 100 of the sixth embodiment, the light receiving element 2 as a part of the light receiving device 12 is fixed to the carrier 5 by the metal bonding material 11 which does not produce thermal curing shrinkage, and the lens 9 as a part of the light receiving device 12 is fixed to the carrier 5 by the resin bonding material 10 which produces thermal curing shrinkage. When the resin bonding material 10 is exposed to an ambient temperature higher than room temperature, it produces thermal curing shrinkage according to the exposure time to the ambient temperature higher than room temperature, and as shown by the arrow 23, the thickness in the Y direction decreases.

[0119] The lens 9 moves toward the surface side of the fourth mounting portion 28 by the thermal curing and shrinking of the resin bonding material 10, and the lens 3 moves toward the surface side of the second mounting portion 26 by the thermal curing and shrinking of the resin bonding material 8. The lens 9 and the lens 3 that have passed the exposure time are represented as the lens 9a and the lens 3a represented by the dotted lines. As the exposure time passes, the positional relationship of the semiconductor laser 1, the light receiving element 2 constituting the light receiving device 12, and the lens 9, the lens 3, and the optical fiber 4 with respect to the back surface 24 of the carrier 5, that is, the positional relationship in the Y direction changes. Therefore, in the optical module 100 of the sixth embodiment, the optical coupling efficiency of the semiconductor laser 1 and the light receiving device 12, and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 change in the same manner as the optical module 100 of the second embodiment.

[0120] In the first example of the optical module 100 of the sixth embodiment, the second mounting portion 26, the first mounting portion 25, the fourth mounting portion 28, and the third mounting portion 27 are arranged from the side close to the optical fiber 4. The range from the dotted line 53a to the dotted line 53b is the second mounting portion 26, and the range from the dotted line 53b to the dotted line 53c is the first mounting portion 25. The range from the dotted line 53c to the dotted line 54a is the fourth mounting portion 28, and the range from the dotted line 54a to the dotted line 54b is the third mounting portion 27. The second mounting portion 26 is a portion of the recessed portion 65 formed on the surface side of the carrier 5, and the surface of the second mounting portion 26 corresponds to the bottom surface of the recessed portion 65 on the side opposite to the back surface 24. The length d1 of the surface of the first mounting portion 25 and the surface of the second mounting portion 26 in the Y direction corresponds to the depth of the recessed portion 65. The third mounting portion 27 is a portion of the recessed portion 68 formed on the surface side of the carrier 5, and the surface of the third mounting portion 27 corresponds to the bottom surface of the recessed portion 68 on the side opposite to the back surface 24. The length d3 between the surface of the fourth mounting portion 28 and the surface of the third mounting portion 27 in the Y direction corresponds to the depth of the recess 68. The surface of the first mounting portion 25 and the surface of the fourth mounting portion 28 are flat surfaces without steps.

[0121] As described above, the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 and the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 with respect to the exposure time are the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic, respectively. The optical module 100 of the sixth embodiment performs automatic light output control, and determines the initial positions of the lens 9 and the lens 3, which are part of the optical receiver 12 and move toward the surface side of the carrier 5 with the passage of exposure time, with the back surface 24 of the carrier 5 as a reference, so that the change trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same. Therefore, when an irreversible composite relative position shift occurs between the semiconductor laser 1 and the optical fiber 4 due to a high temperature environment, the change of the light output can be suppressed.

[0122] exist Fig.29 , an example of an optical module 100 is shown in which the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic have an increasing trend, that is, the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic increase over time within a certain period from the initial stage. Fig.29In the first example of the optical module 100 of embodiment 6 shown, the initial positions of the semiconductor laser 1, the end portion of the optical fiber 4, the lens 3, the light receiving element 2 constituting the light receiving device 12, and the lens 9 with respect to the back side 24 of the carrier 5 are determined in such a manner that the changing trends of the first light coupling efficiency characteristics and the second light coupling efficiency characteristics generated with the passage of exposure time become the same, for example, in such a manner that the changing trends become the same with an increasing trend within a certain period from the initial stage (the above-mentioned second light coupling efficiency setting condition).

[0123] The monitor light 17 emitted from the emission portion 39, which is the region on the second end face 72 side of the active layer 31 of the semiconductor laser 1, is focused by the lens 9, and the focused monitor light 17 is received by the light receiving portion 32 of the light receiving element 2. Fig.33 , Fig.34 An example of the optical coupling efficiency characteristics of the semiconductor laser 1 and the light receiving element 2 of the light receiving device 12 when the reference time t1 is set to 2000 hours, and an example of the optical coupling efficiency characteristics of the semiconductor laser 1 and the optical fiber 4 when the reference time t1 is set to 2000 hours are shown. The horizontal axis is the exposure time, i.e., the exposure time, and the vertical axis is the optical coupling efficiency. Fig.33 The optical coupling efficiency characteristic 48 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the light receiver 12 and the exposure time. The optical coupling efficiency characteristic 48 increases with the exposure time, and is a characteristic whose changing trend is an increasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e15 and e16, respectively. Fig.34 The optical coupling efficiency characteristic 49 shown shows the relationship between the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 and the exposure time. The optical coupling efficiency characteristic 49 increases with the exposure time, and is a characteristic whose changing trend is an increasing trend. The optical coupling efficiencies at exposure times 0 and t1 are e17 and e18, respectively.

[0124] The change in the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4 related to the position of the semiconductor laser 1 and the optical fiber 4 is the same as in Embodiment 2 and will not be described again. The change in the optical coupling efficiency of the semiconductor laser 1 and the optical receiver 12 related to the position of the semiconductor laser 1 and the optical receiver 12 will be described.

[0125] exist Fig.31 The Y-direction positions of the lens 9 and the light receiving element 2 are shown when the exposure time is 0, that is, at the initial time. Fig.32 FIG. 6 shows a beam cross section 61 of the focused monitor light 17 at the light receiving surface 37 in this case. Fig.31 The Y-direction positions of the lens 9a and the light receiving element 2 are shown when the exposure time is longer than t1, that is, after the reference time has passed. Fig.32FIG. 6 shows a beam cross section 61a of the monitoring light 17 after being focused on the light receiving surface 37 in this case. Since the monitoring light 17 is focused, the monitoring light 17 is Fig.10 In comparison, the beam cross-sectional area becomes smaller. Fig.29 , Fig.31 , Fig.32 The example shown is that the monitor light 17 at the light receiving surface 37 moves to the negative side in the Y direction as the lens 9 moves to the negative side in the Y direction.

[0126] The optical coupling efficiency between the semiconductor laser 1 and the photoreceiver 12 changes according to the increase or decrease of the beam cross-sectional area of ​​the monitor light 17 incident on the photoreceiving surface 37, that is, the light receiving area. When the exposure time is 0, the monitor light 17 advances toward the negative side in the Z direction along the lens center axis 14 of the lens 9, for example, to a position where the area of ​​light received including the light receiving portion end 35a of the photoreceiving surface 37 becomes half of the beam cross section 61. When the exposure time is t1 or longer, the monitor light 17 passes through a position closer to the positive side in the Y direction than the lens center axis 14a of the lens 9a after the monitor light 17 has moved toward the negative side in the Y direction, and thus the monitor light 17a that has advanced toward the negative side in the Y direction from the monitor light 17 is incident on the photoreceiving surface 37 of the photoreceiving element 2 of the photoreceiver 12. The beam cross section 61a of the monitor light 17a at the photoreceiving surface 37 moves toward the negative side in the Y direction. The area of ​​the beam cross section 61 at the light receiving surface 37 is smaller than the area of ​​the beam cross section 61a at the light receiving surface 37, and the light receiving area of ​​the received light increases with the exposure time, so the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 increases with the exposure time.

[0127] In the first example of the optical module 100 of the sixth embodiment, the monitor light 17 of the semiconductor laser 1 introduced into the light receiving element 2 can be focused by the lens 9, similarly to the outgoing light 16 of the semiconductor laser 1 introduced into the optical fiber 4. Therefore, the amount of change in the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 caused by the thermal curing shrinkage of the resin bonding material 10 is likely to be larger than that of the optical module 100 of the second embodiment in which the light receiving element 12 does not include the lens 9. This is because if the area of ​​the beam cross section at the light receiving surface 37 is small, the proportion of the area away from the light receiving surface 37 becomes larger than that in the case where the area of ​​the beam cross section is large even if the moving distance in the Y direction is the same. Therefore, it is easy to design so that the increase in the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 caused by the passage of the exposure time in the high temperature environment is equal to the increase in the optical coupling efficiency of the semiconductor laser 1 and the optical fiber 4.

[0128] In the first example of the optical module 100 of the sixth embodiment, when the automatic light output control is performed, the change in the light coupling efficiency in the light receiving element 2 is larger than that in the optical module 100 of the second embodiment, so the correction amount of the light output of the optical module 100 becomes larger. As described in the third embodiment, the first example of the optical module 100 of the sixth embodiment can improve the detection sensitivity of the composite relative position shift between the semiconductor laser 1 and the optical fiber 4 generated with the passage of exposure time, and can increase the correction speed of the light coupling efficiency associated with the composite relative position shift between the semiconductor laser 1 and the optical fiber 4 generated with the passage of exposure time. Therefore, the first example of the optical module 100 of the sixth embodiment can suppress the change of the light output with a smaller change range than the optical module 100 of the second embodiment.

[0129] In the first example of the optical module 100 of the sixth embodiment, since the semiconductor laser 1 and the light receiving element 2 are fixed to the carrier 5 by the metal bonding materials 6 and 11, it is difficult to fine-tune the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2. Therefore, by setting the thickness of the resin bonding material 10 of the lens 9, the length d3 of the recess 68 in the Y direction, etc., the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 is offset from the position where it is, for example, at a maximum or approximately maximum, to the positive side in the Y direction. In addition, as described in the second embodiment, the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is offset from the position where it is at a maximum or approximately maximum to the negative side in the Y direction. In this way, by setting the initial positions of the semiconductor laser 1, the terminal end of the optical fiber 4, the light receiver 12, and the lens 3 with respect to the back side 24 of the carrier 5 as a reference, the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic can be increased over time at least within a certain period from the initial stage. Fig.29 , an example is shown in which the thickness of the resin bonding material 8 in the Y direction is equal to the thickness of the resin bonding material 10 in the Y direction. In the case where the resin bonding material 8 of the lens 3 and the resin bonding material 10 of the lens 9 are made of the same material, if the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 is set in the same manner as the optical module 100 of the second embodiment, and the first condition or the second condition described in the fifth embodiment is satisfied, the increase in the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 caused by the passage of exposure time in a high temperature environment can be made equal to the increase in the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4.

[0130] Next, a second example of the optical module 100 according to the sixth embodiment will be described. Fig.35 The second example of the optical module 100 of the sixth embodiment shown in FIG. Fig.29The first example of the optical module 100 of the sixth embodiment shown is different in that the surface of the fourth mounting portion 28 of the fixed lens 9 is located on the positive side of the Y direction relative to the surface of the first mounting portion 25 of the fixed semiconductor laser 1 and the surface of the third mounting portion 27 of the fixed light receiving element 2, and the monitor light 17 that is initially bent toward the positive side of the Y direction by the lens 9 is received by the light receiving element 2, and as the exposure time passes, the monitor light 17 moves toward the negative side of the Y direction and is received by the light receiving element 2. The parts that are different from the first example of the optical module 100 of the sixth embodiment will be mainly described.

[0131] The fourth mounting portion 28 is a portion of the convex portion 67 formed on the surface side of the carrier 5, and the surface of the fourth mounting portion 28 corresponds to the top surface of the convex portion 67 on the side opposite to the back surface 24. The length h1 of the surface of the fourth mounting portion 28, the surface of the third mounting portion 27, and the surface of the first mounting portion 25 in the Y direction corresponds to the height of the convex portion 67. The surface of the first mounting portion 25 and the surface of the third mounting portion 27 have no step difference.

[0132] exist Fig.37 The Y-direction positions of the lens 9 and the light receiving element 2 are shown when the exposure time is 0, that is, at the initial time. In this case, the beam cross section 61 of the focused monitoring light 17 at the light receiving surface 37 is shown. Fig.32 Same. Fig.37 The Y-direction positions of the lens 9a and the light receiving element 2 when the exposure time is greater than or equal to t1, that is, after the reference time has elapsed, and the beam cross section 61a of the focused monitoring light 17 on the light receiving surface 37 and Fig.32 Since the monitoring light 17 is focused, the same as in the second embodiment Fig.10 In comparison, the beam cross-sectional area becomes smaller. Fig.35 , Fig.37 , Fig.32 The example in which the monitor light 17 at the light receiving surface 37 moves to the negative side in the Y direction as the lens 9 moves to the negative side in the Y direction is shown.

[0133] When the exposure time is 0, the monitoring light 17 passes through a position closer to the negative side in the Y direction than the lens center axis 14 of the lens 9, and the monitoring light 17 bent toward the positive side in the Y direction by the lens 9 is incident on the light receiving surface 37 of the light receiving element 2 of the light receiving device 12. For example, the area of ​​light received including the light receiving portion end 35a of the light receiving surface 37 is half of the beam cross section 61. When the exposure time is longer than t1, the monitoring light 17 passes through the lens center axis 14a of the lens 9a after being moved toward the negative side in the Y direction by the lens 9, and thus the monitoring light 17a traveling toward the negative side in the Y direction by the monitoring light 17 is incident on the light receiving surface 37 of the light receiving element 2 of the light receiving device 12. Fig.32As shown, the beam cross section 61a of the monitoring light 17a at the light receiving surface 37 moves to the negative side in the Y direction. The area of ​​the beam cross section 61 at the light receiving surface 37 is smaller than the area of ​​the beam cross section 61a at the light receiving surface 37, and the light receiving area of ​​the received light increases with the exposure time, so the optical coupling efficiency of the semiconductor laser 1 and the light receiving element 2 increases with the exposure time.

[0134] Next, a third example of the optical module 100 according to Embodiment 6 is described. The third example of the optical module 100 according to Embodiment 6 is different from the first example of the optical module 100 according to Embodiment 6 in the surface of the carrier 5 between the dotted lines 53b and 54b, the size of the lens 9, and the traveling direction of the monitoring light 17. The parts different from the first example of the optical module 100 according to Embodiment 6 are mainly described.

[0135] The surface of the first mounting portion 25, the surface of the fourth mounting portion 28, and the surface of the third mounting portion 27 are planes with no step difference. Fig.39 The Y-direction positions of the lens 9 and the light receiving element 2 are shown when the exposure time is 0, that is, at the initial time. In this case, the beam cross section 61 of the focused monitoring light 17 at the light receiving surface 37 is shown. Fig.32 Same. Fig.39 The Y-direction positions of the lens 9a and the light receiving element 2 when the exposure time is greater than or equal to t1, that is, after the reference time has elapsed, and the beam cross section 61a of the focused monitoring light 17 on the light receiving surface 37 and Fig.32 Since the monitoring light 17 is focused, the same as in the second embodiment Fig.10 In comparison, the beam cross-sectional area becomes smaller. Fig.38 , Fig.39 , Fig.32 The example shows that monitor light 17 at light receiving surface 37 moves to the negative side in the Y direction as lens 9 moves to the negative side in the Y direction. Monitor light 17 when exposure time is 0 and monitor light 17a when exposure time is equal to or longer than t1 are the same as those in the second example.

[0136] In the second and third examples of the optical module 100 according to the sixth embodiment, the light receiver 12 in the optical module 100 according to the second embodiment includes the light receiving element 2 and the lens 9 as in the first example. Therefore, the same effects as those of the first example of the optical module 100 according to the sixth embodiment are achieved.

[0137] In the optical module 100 of the sixth embodiment, the semiconductor laser 1 and the light receiving element 2 are simultaneously fixed to the carrier 5 by the metal bonding materials 6 and 11, and the lens 3 and the lens 9 are simultaneously fixed to the carrier 5 by the resin bonding materials 8 and 10. Therefore, compared with the optical module 100 of the second embodiment, the fixing time of the light receiving element 12 can be shortened. In addition, in the optical module 100 of the sixth embodiment, since the light receiving element 2 is fixed to the carrier 5 by the metal bonding material 11, the heat dissipation of the light receiving element 2 can be improved compared with the optical module 100 of the second embodiment.

[0138] In the first to third examples of the optical module 100 of the sixth embodiment, instead of shifting the optical fiber 4 to the negative side in the Y direction, the lens 3 may be shifted to the positive side in the Y direction as in the second example of the second embodiment. Even in this case, the initial positions of the semiconductor laser 1, the end of the optical fiber 4, the lens 3, and the light receiving element 2 as the light receiving device 12 with respect to the back surface 24 of the carrier 5 may be determined so that the change trends of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic with the passage of exposure time become the same, and so that the change trends become the same in a certain period from the initial stage with an increasing trend. In addition, the optical module 100 of the sixth embodiment may be such that the amount of thermal curing shrinkage of the resin bonding material 10 of the light receiving device 12 with the passage of exposure time is greater than the amount of thermal curing shrinkage of the resin bonding material 8 of the lens 3 as described in the third embodiment. In this case, the optical module 100 of the sixth embodiment makes the thermal curing shrinkage of the resin bonding material 10 greater than that of the resin bonding material 8 as the exposure time passes, thereby increasing the correction amount of the light output when the automatic light output control is performed, thereby being able to suppress the change of the light output with a small change amplitude.

[0139] also, Fig.34 The optical coupling efficiency characteristic 49 shown in the embodiment 2 may also be Fig.13 , Fig.14 As described in , when the peak value is reached, the change ends and becomes constant. In this case, the optical module 100 of the sixth embodiment performs automatic light output control, and determines the initial positions of the lens 9 and the lens 3 as part of the light receiver 12, which move to the surface side of the carrier 5 with the passage of exposure time, based on the back surface 24 of the carrier 5 in such a way that the change trends of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic become the same within a certain period from the initial stage. Therefore, when an irreversible composite relative position shift is generated between the semiconductor laser 1 and the optical fiber 4 due to a high temperature environment, the change of the light output can be suppressed.

[0140] In addition, as described in the second embodiment, the optical coupling efficiency characteristics of the semiconductor laser 1 and the optical receiver 12 may also stop changing and become constant when the optical coupling efficiency characteristics reach a peak value halfway to the reference time t1. In this case, the optical coupling efficiency between the semiconductor laser 1 and the optical fiber 4 and the optical coupling efficiency between the semiconductor laser 1 and the light receiving element 2 change in the same manner as the exposure time passes, so the change trends of the first optical coupling efficiency characteristics and the second optical coupling efficiency characteristics change in the same manner. Therefore, the optical module 100 of the sixth embodiment performs automatic light output control, and determines the initial positions of the lens 9 and the lens 3, which are part of the optical receiver 12 and move to the surface side of the carrier 5 as the exposure time passes, with the back side 24 of the carrier 5 as the reference, so that the change trends of the first optical coupling efficiency characteristics and the second optical coupling efficiency characteristics become the same, so that when an irreversible composite relative position shift occurs between the semiconductor laser 1 and the optical fiber 4 due to a high temperature environment, the change of the light output can be suppressed.

[0141] In addition, although various illustrative embodiments and examples are described in this application, the various features, forms and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can also be applied to the embodiment alone or in various combinations. Therefore, countless unillustrated variations can be imagined within the technical scope disclosed in the specification of this application. For example, it includes the case where at least one constituent element is deformed, added or omitted, and also includes the case where at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0142] Description of Reference Numerals

[0143] 1... semiconductor laser; 2, 2a... light receiving element; 3, 3a... lens; 4, 4s... optical fiber; 5... carrier; 6... metal bonding material; 7... resin bonding material (first resin bonding material); 8... resin bonding material (second resin bonding material); 9, 9a... lens; 10... resin bonding material (first resin bonding material); 11... metal bonding material; 12... light receiving device; 15... central axis; 16, 16a... outgoing light; 17, 17a... monitoring light; 18... monitoring light; 20... control circuit; 24... back side; 25... first mounting portion; 26... second mounting portion; 27 ...third mounting portion; 28...fourth mounting portion; 30, 30a...light receiving element; 37...light receiving surface; 39...emitting portion; 40...optical axis; 41, 41a...optical coupling efficiency characteristics; 42...optical coupling efficiency characteristics; 43...optical coupling efficiency characteristics; 44...optical coupling efficiency characteristics; 45a, 45b...optical coupling efficiency characteristics; 46...optical coupling efficiency characteristics; 47...optical coupling efficiency characteristics; 48...optical coupling efficiency characteristics; 49...optical coupling efficiency characteristics; 71...first end surface; 72...second end surface; 100...optical module; Im...monitoring current (output current); Iop...injection current

Claims

1. An optical module is an optical module that transmits the output light emitted by a semiconductor laser through an optical fiber, wherein: The optical module has: The semiconductor laser and the optical fiber; a light receiver for receiving monitoring light emitted from an end face opposite to an emission end face from which the emission light is emitted; A lens for focusing the emitted light; A carrier carrying the semiconductor laser, the light receiver and the lens; as well as a control circuit that controls the injection current of the semiconductor laser so that the output current of the light receiver becomes constant, The semiconductor laser is fixed to the carrier via a metal bonding material. At least a portion of the light receiver and the lens are fixed to the carrier by a first resin bonding material and a second resin bonding material that shrink during thermal curing, respectively. The position of the terminal portion of the optical fiber into which the emitted light is introduced is fixed with respect to the back side of the carrier, wherein the back side is the surface opposite to the surface of the mounting portion on which the semiconductor laser, the light receiver, and the lens are mounted. The optical coupling efficiency between the semiconductor laser and the light receiver and the optical coupling efficiency between the semiconductor laser and the optical fiber relative to the exposure time of the optical module to an ambient temperature higher than room temperature are respectively defined as a first optical coupling efficiency characteristic and a second optical coupling efficiency characteristic, The initial positions of the semiconductor laser, the end portion of the optical fiber, the light receiver, and the lens when the exposure time of the optical module is 0 are determined with reference to the back side of the carrier in such a way that the changing trends of the first optical coupling efficiency characteristic and the second optical coupling efficiency characteristic become the same.

2. The optical module according to claim 1, wherein: The variation trend of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic is a decreasing trend.

3. The optical module according to claim 1, wherein: The variation trend of the first light coupling efficiency characteristic and the second light coupling efficiency characteristic is an increasing trend.

4. The optical module according to claim 1 or 2, wherein: The optical fiber is arranged so that the outgoing light in the absence of the lens is incident on the central axis of the optical fiber.

5. The optical module according to claim 1 or 3, wherein: The optical fiber is arranged so that the outgoing light in the absence of the lens is incident on a portion of the optical fiber that is distant from a central axis in a direction perpendicular to the back surface of the carrier.

6. The optical module according to claim 1 or 3, wherein: The optical fiber is arranged so that the outgoing light that has passed through the lens in the initial position is incident on a portion of the optical fiber that is distant from a central axis in a direction perpendicular to the back surface of the carrier.

7. The optical module according to claim 2, wherein: The monitoring light is light that is more diffuse than the emitted light, The light receiving surface of the light receiver is arranged on the back side of the carrier relative to the emission portion of the monitor light and does not intersect with the optical axis of the monitor light.

8. The optical module according to any one of claims 1 to 3, wherein: The light receiver includes another lens for focusing the monitor light and a light receiving element for receiving the monitor light focused by the other lens. The light receiving element is fixed to the carrier via the metal bonding material. The other lens is fixed to the carrier via the first resin bonding material, The first optical coupling efficiency characteristic is the optical coupling efficiency between the semiconductor laser and the light receiving element relative to the exposure time.

9. The optical module according to any one of claims 1 to 3 and 7, wherein: The light receiver is a light receiving element, and the light receiving element is fixed to the carrier via the first resin bonding material.

10. The optical module according to any one of claims 1 to 3 and 7, wherein: The amount of thermal curing shrinkage of the first resin bonding material generated when exposed to an ambient temperature higher than room temperature is greater than the amount of thermal curing shrinkage of the second resin bonding material.

11. The optical module according to claim 10, wherein: A thickness of the first resin bonding material in a direction perpendicular to the back surface of the carrier is greater than a thickness of the second resin bonding material in the direction perpendicular to the back surface of the carrier.

12. The optical module according to claim 10, wherein: The second resin bonding material is a bonding resin that is thermally cured and shrunk earlier than the first resin bonding material.

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