JP2016092088A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module which inhibits changes of optical output relative to temperature fluctuation.SOLUTION: The optical module according to an embodiment includes: a transparent member; a base member; and support members disposed between the transparent member and the base member. The transparent member has: a laser beam incidence surface; an emission surface facing the incidence surface; and a first surface connecting the incidence surface with the emission surface. The base member is provided on the first surface side of the transparent member.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to an optical module.

  Applications of optical modules used in WDM (Wavelength Division Multiplexing) optical communication systems are expanding. In order to cope with this, an optical module in which various functions are integrated is required. For example, an optical module incorporating a plurality of semiconductor lasers or light receiving elements and an optical multiplexer will play an important role as a transceiver for large-capacity digital communication. However, there is a limit to miniaturization of optical functional devices such as optical multiplexers. For example, an optical module equipped with an optical multiplexer is large in size and consumes a large amount of power to adjust its temperature.

JP 2005-249966 A

  Embodiments provide an optical module that suppresses changes in optical output with respect to temperature fluctuations.

  The optical module according to the embodiment includes a transparent member, a base member, and a plurality of support members disposed between the transparent member and the base member. The transparent member has an incident surface for laser light, an exit surface facing the entrance surface, and a first surface connecting the entrance surface and the exit surface. The base member is provided on the first surface side of the transparent member.

  According to the embodiment, it is possible to realize an optical module that suppresses a change in optical output with respect to temperature fluctuation.

It is a schematic diagram which shows the optical module which concerns on 1st Embodiment. It is another schematic diagram which shows the optical module which concerns on 1st Embodiment. It is a graph showing the characteristic of the optical module which concerns on 1st Embodiment. It is a schematic cross section which shows the optical module which concerns on a comparative example. It is a graph showing the characteristic of the optical module which concerns on a comparative example. It is a graph showing another characteristic of the optical module which concerns on a comparative example. It is a graph showing the other characteristic of the optical module which concerns on a comparative example. It is a graph showing another characteristic of the optical module which concerns on 1st Embodiment. It is a schematic diagram which shows the optical module which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same parts in the drawings are denoted by the same reference numerals, detailed description thereof will be omitted as appropriate, and different parts will be described as appropriate.

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

  The optical module 1 includes a plurality of semiconductor lasers 10 and a transparent member 20. Here, “transparent” means transmitting laser light emitted from the semiconductor laser. Further, the present invention is not limited to the case where 100% of the laser beam is transmitted, and a part of the laser beam may be absorbed.

  The transparent member 20 is, for example, an optical multiplexer, and emits light obtained by combining the emitted light of a plurality of semiconductor lasers. The transparent member 20 includes a laser light incident surface 21 and an output surface 23 that faces the incident surface 21. The transparent member 20 includes a first surface 25 that connects the incident surface 21 and the emission surface 23, and a second surface 27 that is opposite to the first surface 25. For the transparent member 20, for example, a glass material such as quartz is used.

  The semiconductor laser 10 and the transparent member 20 are accommodated in a metal case 50, for example. The metal case 50 includes a base plate 51, a frame 53, and a lid 55. For the base plate 51, for example, copper tungsten (CuW) is used. For the frame 53, for example, Kovar is used. A window 57 that transmits laser light is provided in a portion of the frame 53 that faces the emission surface 23 of the transparent member 20.

  As shown in FIG. 1A, the laser holder 13 and the base member 30 are disposed on the base plate 51. The semiconductor laser 10 is mounted on the laser holder 13 so that the emitted light is incident on the incident surface of the transparent member 20. The laser holder 13 includes wiring (not shown) that is electrically connected to the semiconductor laser 10. The laser holder 13 may include a temperature adjustment device, for example, a Peltier element.

  The transparent member 20 is placed on the base member 30. For the base member 30, for example, a ceramic material such as alumina or aluminum nitride is used. The base member 30 may be a metal.

  A plurality of support members 40 are disposed between the transparent member 20 and the base member 30. In order to stably support the transparent member 20, three or more support members 40 are preferably disposed. For the support member 40, for example, a ceramic material such as alumina or aluminum nitride is used.

  Further, the embodiment is not limited to the above example. For example, the transparent member 20 may be disposed on the base plate 51 via the support member 40 without using the base member 30.

  As shown in FIG. 1B, in this example, four semiconductor lasers 10a to 10d are arranged. However, the number of semiconductor lasers is arbitrary and is not limited to this example. The wavelengths of the laser beams emitted from the semiconductor lasers 10a to 10d are different.

  On the incident surface 21 of the transparent member 20, four band pass filters 13 a to 13 d facing the semiconductor lasers 10 a to 10 d are provided. The band pass filter 13a facing the semiconductor laser 10a transmits the laser light emitted from the semiconductor laser 10a and reflects the laser light emitted from the other semiconductor lasers 10b to 10c.

  On the other hand, an antireflection film 17 is partially provided on the emission surface 23 of the transparent member 20. The antireflection film 17 is provided, for example, at a portion facing the band pass filter 13a. As a result, the laser light emitted from the semiconductor laser 10 a passes through the bandpass filter 13 a, the transparent member 20, and the antireflection film 17, and is emitted to the outside from the window 57 provided in the frame 53.

  A reflective film 15 is provided on the other part of the emission surface 23 of the transparent member 20. The laser light emitted from the semiconductor lasers 10b to 10d repeats multiple reflections between the reflection film 15 and the band-pass filters 13a to 13d inside the transparent member 20, and is finally provided with the antireflection film 17 The light is emitted from the window 57 and emitted from the window 57 to the outside.

  Thus, the laser beams emitted from the semiconductor lasers 10a to 10d are combined in the transparent member 20. The propagation distance of each laser beam in the transparent member 20 becomes longer as the incident position of the laser beam becomes farther from the portion where the antireflection film 17 is provided. That is, the propagation distance of the laser light emitted from the semiconductor laser 10d is the longest.

  FIG. 2 is another schematic diagram showing the optical module 1 according to the first embodiment. FIG. 2A is a plan view showing the component arrangement of the optical module 1, and FIG. 2B is a partial cross section showing the support structure of the transparent member 20.

  As shown in FIG. 2A, for example, four support members 40 are arranged under the transparent member 20. As described above, the transparent member 20 can be stably held by arranging three or more support members 40. Moreover, although the shape of the support member 40 shown to Fig.2 (a) is a square, it is not necessarily limited to this. For example, it may be circular. Further, depending on the shape of the support member 40, the transparent member 20 may be stably held even with two support members. For example, two support members 40 extending along the entrance surface 21 or the exit surface 23 may be disposed.

As shown in FIG. 2B, the base member 30 is fixed on the base plate 51 via the adhesive layer 33. Further, the support member 40 is fixed on the base member 30 via the adhesive layer 43 (first adhesive layer). The transparent member 20 is connected to the support member 40 via the adhesive layer 45 (second adhesive layer). For the adhesive layers 33, 43, and 45, for example, an adhesive containing a silver (Ag) paste or an epoxy resin can be used.
The interval W ₁ between the plurality of support members 40 is preferably wider than the width W ₂ of the support member 40 in the direction parallel to the first surface 25 of the transparent member 20.

  FIG. 3 is a graph showing characteristics of the optical module 1 according to the first embodiment. The horizontal axis represents the case temperature, and the vertical axis represents the laser light power Pf output from the optical module 1. The output power Pf is shown as a relative value with respect to the output power at 25 ° C. The same applies to other graphs shown below.

  The characteristic shown in FIG. 3 is the output characteristic of the laser beam emitted from the semiconductor laser 10d. That is, it is an output characteristic of laser light having the longest propagation distance in the transparent member 20, and is most easily influenced by, for example, distortion of the transparent member 20 due to temperature change. As shown in FIG. 3, the output fluctuation of the optical module 1 is suppressed to 2 dB or less in the temperature range of −5 ° C. to 75 ° C.

  FIG. 4 is a schematic cross-sectional view showing an optical module 2 according to a comparative example. As shown in FIG. 4, in the optical module 2, the transparent member 20 is placed directly on the base member 60. Moreover, the transparent member 20 is fixed on the base member 60 through an adhesive layer (Ag paste) (not shown).

  5 to 7 show the characteristics of the optical modules 2a to 2c. (A) of each figure is a top view showing component arrangement | positioning, (b) is a graph showing the output characteristic of optical module 2a-2c. In the optical module 2 shown in each drawing, the position or size of the adhesive layer provided between the transparent member 20 and the base member 60 is different. Moreover, (b) of each figure is an output characteristic of the laser beam emitted from the semiconductor laser 10d, and also represents a propagation characteristic in the transparent member 20 at the same time.

In the optical module 2 a shown in FIG. 5A, four adhesive layers 61 are provided between the transparent member 20 and the base member 60.
As shown in FIG. 5B, the output of the optical module 2a decreases on both the low temperature side and the high temperature side. The range of the output fluctuation in the temperature range of −5 ° C. to 75 ° C. exceeds 9 dB.

In the optical module 2 b shown in FIG. 6A, an adhesive layer 63 is provided between the transparent member 20 and the base member 60. One adhesive layer 63 is provided at the center of the transparent member 20.
As shown in FIG. 6B, the output of the optical module 2a greatly decreases on the high temperature side. The range of the output fluctuation in the temperature range of −5 ° C. to 75 ° C. is about 8 dB.

In the optical module 2 c shown in FIG. 7A, an adhesive layer 65 is provided between the transparent member 20 and the base member 60. One adhesive layer 65 is provided in the center of the transparent member 20 and is smaller than the adhesive layer 63.
As shown in FIG. 7B, the output of the optical module 2c decreases by about 2 dB on the low temperature side, but the change on the high temperature side is suppressed. The range of the output fluctuation in the temperature range of −5 ° C. to 75 ° C. is about 2 dB.

  Thus, the output characteristics of the optical module 2 depend on the arrangement or size of the adhesive layer between the transparent member 20 and the base member 60. And the temperature change of the output of the optical module 2 is most suppressed when the small contact bonding layer 65 is arrange | positioned in the center of the transparent member 20. FIG. However, in the configuration in which the transparent member 20 and the base member 60 are connected by the adhesive layer 65 at the center of the transparent member 20, there is a concern that the adhesive strength is reduced. That is, there is a risk that reliability may be reduced due to the peeling of the optical module 2c.

  When the output characteristics of the optical module 2c in FIG. 7B and the output characteristics of the optical module 1 in FIG. 3 are compared, the output fluctuation of the optical module 1 is 2 dB or less, and the temperature change is further suppressed as compared with the optical module 2c. I understand that Further, the arrangement of the support member 40 of the optical module 1 is the same as the arrangement of the adhesive layer 61 of the optical module 2a, but the fluctuation of the optical output is greatly suppressed.

  FIG. 8 is a graph showing output characteristics of the laser beams emitted from the semiconductor lasers 10a to 10d. FIG. 8A shows the characteristics of the optical module 1, and FIG. 8B shows the characteristics of the optical module 2. 8A and 8B, the output characteristics of the laser beam emitted from the semiconductor laser 10a is La, and the output characteristics of the laser beams emitted from the semiconductor lasers 10b to 10d are Lb to Ld, respectively. It is.

  As shown in FIG. 8A, in the optical module 1, the light output slightly decreases on the high temperature side, but the fluctuation range is 2 dB or less. Further, the fluctuation range in the output characteristics of the laser light emitted from the semiconductor lasers 10a to 10c is suppressed to 1 dB.

  The optical module 2 shown in FIG. 8B is a sample different from the optical module 2c shown in FIG. 7, but the fluctuation width of each of the propagation characteristics of the semiconductor lasers 10a to 10d is suppressed to 2 dB or less. . However, the temperature change tendency of each laser beam varies. That is, the output (Ld) of the laser beam emitted from the semiconductor laser 10d is decreased on both the low temperature side and the high temperature side. On the other hand, the output (Lb) of the laser beam emitted from the semiconductor laser 10b decreases on the low temperature side and increases on the high temperature side. As a result, the output fluctuation width of the optical module 2 exceeds 2 dB.

  Thus, in the optical module 1 according to the present embodiment, it is possible to suppress changes in output with respect to temperature changes in the operating environment. In the optical module 1, a plurality of support members 40 are disposed between the transparent member 20 and the base member 30. Thereby, the adhesive strength of the transparent member 20 can be improved. That is, in this embodiment, it is possible to realize a highly reliable optical module 1 that suppresses a temperature change in optical output.

[Second Embodiment]
FIG. 9 is a schematic diagram showing the optical module 3 according to the second embodiment. FIG. 9A is a cross-sectional view illustrating the optical module 3. FIG. 9B is a partial cross-sectional portion showing an example of a support structure for the transparent member 20.

  As shown in FIG. 9A, in the optical module 3, the transparent member 20 is placed on the base member 70. The base member 70 has a plurality of convex portions 71 on the surface on the transparent member 20 side. The transparent member 20 is fixed on the convex portion 71 through an adhesive layer (not shown).

  For the base member 70, for example, a ceramic material such as alumina or aluminum nitride can be used. The base member 70 may be a metal. Moreover, it is preferable that the mutual space | interval of the convex part 71 is wider than the width | variety of the convex part 71 of the direction parallel to the 1st surface 25 of the transparent member 20. FIG.

As shown in FIG. 9B, the base member 70 is fixed on the base plate 51 via an adhesive layer 73. The convex portion 71 may have an integrated structure as shown in FIG. 9A, or may have a structure including a plurality of protrusions 75. The height H ₁ of the protrusion 75 is preferably higher than the width W _{3 in the} direction parallel to the first surface 25 of the transparent member 20.

  The transparent member 20 is fixed on the plurality of protrusions 75 via the adhesive layer 77. For the adhesive layers 73 and 77, for example, an adhesive containing Ag paste or epoxy resin can be used.

  In the optical module 3, by providing a protrusion on the base member 70, stress generated between the transparent member 20 and the base member 70 is reduced, and distortion of the transparent member is suppressed. Thereby, the temperature change of optical output can be suppressed.

  In the above embodiment, a light emitting module including a plurality of semiconductor lasers and a multiplexer has been described. However, the present invention is not limited to this. For example, the present invention can be applied to a light receiving module including a duplexer and a plurality of light receiving elements.

  As mentioned above, although this invention was demonstrated with reference to one embodiment which concerns on this invention, this invention is not limited to these embodiment. For example, embodiments that have the same technical idea as the present invention, such as design changes and material changes that can be made by those skilled in the art based on the technical level at the time of filing, are also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1-3 ... Optical module, 10 ... Semiconductor laser, 13 ... Laser holder, 13a-13d ... Band pass filter, 15 ... Reflection film, 17 ... Antireflection film, 20 ... Transparent member, 21 ... Incident surface, 23 ... Output surface 25 ... 1st surface, 27 ... 2nd surface, 30, 60, 70 ... Base member, 33, 43, 45, 61, 63, 65, 73, 77 ... Adhesive layer, 40 ... Support member, 50 ... Metal case 51 ... Base plate, 53 ... Frame, 55 ... Lid, 57 ... Window, 71 ... Projection, 75 ... Projection

Claims (5)

A transparent member having an incident surface of laser light, an exit surface facing the entrance surface, and a first surface connecting the entrance surface and the exit surface;
A base member provided on the first surface side of the transparent member;
A plurality of support members disposed between the transparent member and the base member;
With optical module. A first adhesive layer provided between each of the plurality of support members and the base member;
A second adhesive layer provided between each of the plurality of support members and the transparent member;
The optical module according to claim 1, further comprising:   The optical module according to claim 1, wherein at least three support members are disposed between the transparent member and the base member.   The optical module according to claim 1, wherein the transparent member includes a plurality of bandpass filters provided on the incident surface, and includes an antireflection film on a part of the emission surface. A transparent member having an incident surface of laser light, an exit surface facing the entrance surface, and a first surface connecting the entrance surface and the exit surface;
A base member having a plurality of protrusions protruding toward the first surface of the transparent member;
An adhesive layer disposed between the transparent member and each of the plurality of convex portions;
With optical module.

Images