JP6077879B2 - Semiconductor laser module - Google Patents

Description

  The present invention relates to a semiconductor laser module having a semiconductor laser used as a signal light source in an optical communication system.

  In an optical communication system, a semiconductor laser module is widely used as a module for converting a modulated electrical signal into an optical signal (see, for example, Patent Document 1).

  As shown in FIG. 16, the semiconductor laser module as described above includes a semiconductor laser 100 that outputs laser light, an optical fiber 110 as a single mode optical fiber that is optically coupled to the semiconductor laser 100, and the semiconductor laser 100. And a lens 120 that condenses the light emitted from the optical fiber 110 toward the optical fiber 110.

  The semiconductor laser 100 installed in the semiconductor laser module is required to have high output and high stability characteristics (see, for example, Patent Document 2). This is because the intensity of an optical signal used in an optical communication system is gradually attenuated while being transmitted through an optical fiber laid over a long distance.

  The semiconductor laser disclosed in Patent Document 2 has an n-type cladding layer made of n-type InGaAsP (indium / gallium / arsenic / phosphorus) on a semiconductor substrate made of n-type InP (indium / phosphorus), and an optical separation made of InGaAsP. A confinement (SCH) layer, an active layer having a multiple quantum well (MQW) structure composed of InGaAsP, an SCH layer composed of InGaAsP, and a p-type cladding layer composed of p-type InP are sequentially stacked. .

  In the above semiconductor laser, the optical confinement coefficient in the active layer and the SCH layer is reduced in order to achieve high output. Furthermore, by deviating the light distribution toward the n-type cladding layer, light loss due to light absorption between valence bands in the p-type cladding layer is suppressed. For this reason, the spot shape and light intensity distribution of the output light of the semiconductor laser are asymmetric in the layer thickness direction with the active layer as the center, as shown in FIG.

JP 2010-278201 A Japanese Patent No. 3525257

  However, in the conventional semiconductor laser module as disclosed in Patent Document 1, the optical axis of the semiconductor laser 100 and the optical axis of the lens 120 are located on the same straight line as shown in FIG. Therefore, when the semiconductor laser disclosed in Patent Document 2 is used as the semiconductor laser 100, output light having an asymmetric light intensity distribution is incident on the optical fiber 110 while maintaining the asymmetry. Therefore, there is a problem that the coupling efficiency between the semiconductor laser and the optical fiber is poor as compared with the case of using a semiconductor laser that outputs a laser beam having a symmetric light intensity distribution as shown in FIG.

  The present invention has been made to solve such a conventional problem, and in a semiconductor laser module including a semiconductor laser that emits laser light having an asymmetric light intensity distribution, the coupling between the semiconductor laser and the optical fiber is provided. An object of the present invention is to provide a semiconductor laser module capable of improving efficiency.

In order to solve the above-described problem, a semiconductor laser module according to claim 1 of the present invention includes:
A semiconductor laser module comprising: a semiconductor laser in which a plurality of semiconductor layers including an active layer are stacked; an optical fiber; and a lens that collects emitted light from the semiconductor laser toward the optical fiber, The light intensity distribution of the emitted light of the semiconductor laser is asymmetric in the layer thickness direction centering on the active layer, and the optical surface of the lens facing the semiconductor laser is aspheric, and the lens The optical axis of the semiconductor laser and the optical axis of the lens are inclined with respect to the optical axis of the semiconductor laser in a direction toward the semiconductor laser in a direction with a small bias of the asymmetric light intensity distribution. DOO is crossed at a predetermined angle not parallel to each other, said predetermined angle is incident on the optical surface facing from the semiconductor laser in the semiconductor laser of the lens The light intensity distribution of the optical fiber is shaped in a direction perpendicular to the optical axis direction of the optical fiber, and the light incident on the optical surface is relaxed in asymmetry with respect to the optical axis of the optical fiber, and is applied to the optical fiber of the lens. It has the structure set so that it may radiate | emit from the optical surface which opposes .

  With this configuration, the optical surface of the lens facing the semiconductor laser has an aspherical shape, and the optical axis of the emitted light of the semiconductor laser and the optical axis of the lens are not parallel to each other but intersect at a predetermined angle, Laser light with an asymmetric light intensity distribution incident on the lens from the semiconductor laser is shaped in the vertical direction around the optical axis of the optical fiber and emitted from the lens, so that laser light with an asymmetric light intensity distribution is emitted. The coupling efficiency between the semiconductor laser and the optical fiber can be improved.

  The semiconductor laser module according to claim 2 of the present invention further includes a support member for supporting the semiconductor laser, wherein the support member has an optical axis of the semiconductor laser and an optical axis of the lens at the predetermined angle. It has a configuration having an inclined surface for supporting the semiconductor laser in an intersecting state.

  With this configuration, by tilting the optical axis of the semiconductor laser with respect to the optical axis of the lens, the coupling efficiency between the semiconductor laser that emits laser light having an asymmetric light intensity distribution and the optical fiber can be improved.

  According to a third aspect of the present invention, there is provided the semiconductor laser module according to the third aspect of the present invention, wherein the one end face and the other end face are formed in parallel with each other, the semiconductor laser is supported, and the end face of the abutting block is A support member that abuts one end surface; and a lens holder that holds the lens and has an end surface that intersects the optical axis of the held lens, the lens holder including the optical axis of the semiconductor laser and the optical axis of the semiconductor laser. In a state where the optical axis of the lens intersects with the predetermined angle, the edge of the end surface intersecting the optical axis of the lens is fixed to the other end surface of the abutting block. ing.

  With this configuration, by inclining the optical axis of the lens with respect to the optical axis of the semiconductor laser, the coupling efficiency between the semiconductor laser that emits laser light having an asymmetric light intensity distribution and the optical fiber can be improved.

  According to a fourth aspect of the present invention, there is provided a semiconductor laser module comprising: an abutting block having one end face and the other end face; and supporting the semiconductor laser, wherein the one end face abuts against the one end face of the abutting block. A support member in contact with the lens holder, and a lens holder that holds the lens and has an end surface that intersects with the optical axis of the held lens, and is fixed in contact with the other end surface of the abutting block at the end surface. Further, the other end surface of the abutting block has an inclined surface for fixing the lens holder in a state where the optical axis of the semiconductor laser and the optical axis of the lens intersect with each other at the predetermined angle. It has a configuration to make.

  With this configuration, by inclining the optical axis of the lens with respect to the optical axis of the semiconductor laser, the coupling efficiency between the semiconductor laser that emits laser light having an asymmetric light intensity distribution and the optical fiber can be improved.

  According to a fifth aspect of the present invention, in the semiconductor laser module according to the present invention, the semiconductor laser includes an active layer, an n-type clad layer made of InGaAsP and an p-type clad layer made of InP on the substrate made of InP. You may have the structure formed by providing.

  The present invention provides a semiconductor laser module that includes a semiconductor laser that emits laser light having an asymmetric light intensity distribution, and that can improve the coupling efficiency between the semiconductor laser and the optical fiber.

It is a side view showing the composition of the semiconductor laser module as a 1st embodiment. It is a top view which shows the structure of the semiconductor laser module as 1st Embodiment. It is a perspective view of the semiconductor laser with which the semiconductor laser module as a 1st embodiment is provided. It is an expanded sectional view showing the composition of the principal part of the semiconductor laser with which the semiconductor laser module as a 1st embodiment is provided. It is a graph which shows the refractive index characteristic of the semiconductor laser with which the semiconductor laser module as 1st Embodiment is provided. It is a graph which shows the light intensity distribution characteristic of the emitted light of the semiconductor laser with which the semiconductor laser module as 1st Embodiment is provided. It is a side view which shows the structure of the principal part of the semiconductor laser module as 1st Embodiment. It is a graph which shows the relationship between the angle which the optical axis of the semiconductor laser with which the semiconductor laser module as 1st Embodiment is provided, and the optical axis of a lens cross, and coupling loss. It is a side view which shows the structure of the semiconductor laser module as 2nd Embodiment. It is a perspective view which shows the structure of the butting block and lens holder with which the semiconductor laser module as 2nd Embodiment is provided. It is a side view which shows the structure of the principal part of the semiconductor laser module as 2nd Embodiment. It is a side view which shows the structure of the semiconductor laser module as 3rd Embodiment. It is a perspective view which shows the structure of the butting block and lens holder with which the semiconductor laser module as 3rd Embodiment is provided. It is a top view which shows the structure of the semiconductor laser module as 4th Embodiment. It is a side view which shows the structure of the principal part of the semiconductor laser module as 4th Embodiment. It is a side view which shows the structure of the principal part of the conventional semiconductor laser module. It is a figure which shows the asymmetrical spot shape and light intensity distribution of the output light of the conventional semiconductor laser. It is a figure which shows the symmetrical spot shape and light intensity distribution of the output light of the conventional semiconductor laser.

  Embodiments of a semiconductor laser module according to the present invention will be described below with reference to the drawings. In addition, the dimensional ratio of each structure on each drawing does not necessarily correspond with the actual dimensional ratio.

(First embodiment)
First, the configuration of the semiconductor laser module as the first embodiment of the present invention will be described.

  As shown in FIGS. 1 and 2, the butterfly type semiconductor laser module 1 includes a semiconductor laser 10, an optical fiber 11 as a single mode optical fiber, and condensing emitted light from the semiconductor laser 10 toward the optical fiber 11. The lens 12 and the substrate 13 are mainly provided.

  The semiconductor laser 10, the lens 12, and the substrate 13 are housed in a rectangular parallelepiped package (casing) 14 having a hollow inside. The optical fiber 11 is connected to the wall surface 14 a on the front side of the package 14 and guides the light collected by the lens 12 to the outside of the package 14.

  As shown in FIG. 2, a plurality of terminals 15 to / from which signals for controlling the operation of the semiconductor laser module 1 are input / output are attached to both side walls 14 b and 14 c of the package 14 at predetermined intervals. These terminals 15 are soldered to a pattern on a printed board (not shown). Further, a flange portion 16 is provided at a lower front end portion and a lower rear end portion of the package 14, and an attachment hole 17 for screwing the semiconductor laser module 1 to a heat radiating plate (not shown) is provided in the flange portion 16. Yes.

  As shown in FIG. 1, a Peltier element 18 is fixed to the upper surface of the bottom wall 14 d in the package 14. The substrate 13 is fixed on the Peltier element 18.

  Further, in addition to the semiconductor laser 10 and the lens 12, an isolator 19 that prevents return light such as reflected light coming from the optical fiber 11 side and a light emitting end face opposite to the lens 12 side of the semiconductor laser 10 are provided inside the package 14. And a light receiving element 20 that receives light slightly emitted from the light source and monitors the operation of the semiconductor laser 10.

  The substrate 13 is formed of one upper step portion 13b having an upper surface 13a as an inclined surface and two lower step portions 13c and 13d. A semiconductor laser 10 that emits light (laser light) is fixed on the upper stage portion 13 b via a chip carrier 21. A pair of abutting blocks 23 and 24 that support the lens holder 22 that holds the lens 12 and a pedestal 25 that supports the isolator 19 are fixed on the lower step 13c. A PD submount 26 that supports the light receiving element 20 is fixed on the other lower step portion 13d.

  That is, the chip carrier 21, the abutting blocks 23 and 24, the pedestal 25, and the PD submount 26 are fixed on the substrate 13. Here, the upper stage portion 13 b of the substrate 13 constitutes a support member that supports the semiconductor laser 10.

  Here, in the butting blocks 23 and 24, one end surfaces 23a and 24a and the other end surfaces 23b and 24b are formed in parallel to each other with respect to the XZ plane. One end surface of the upper stage portion 13b of the substrate 13 is in contact with one end surface 23a, 24a.

  The lens holder 22 is made of a metal such as stainless steel, and the other end surface 23b, with the end surface 22a orthogonal to the optical axis of the lens 12 in contact with the other end surfaces 23b, 24b of the abutment blocks 23, 24. It is fixed to 24b with solder, welding or adhesive.

  The optical axis of the semiconductor laser 10 passes between the pair of abutting blocks 23 and 24. Here, the optical axis of the semiconductor laser 10 means an axis along the waveguide direction of the emitted light of the semiconductor laser 10.

  A circular emission port for guiding laser light emitted from the semiconductor laser 10 to the outside is formed on the wall surface 14a of the package 14, and a window glass 27 is attached to the front side thereof. A cylindrical ferrule 28 attached to the distal end portion of the optical fiber 11 is fixed to the wall surface 14a of the package 14 by a sleeve 29, and a cylindrical cover 30 surrounding the entire ferrule 28 and a part of the optical fiber 11 is provided. It is fixed to the wall surface 14 a of the package 14.

  With the above configuration, the laser light emitted from the semiconductor laser 10 passes through the lens 12, the isolator 19, and the window glass 27, reaches the wall surface 14 a of the package 14, and enters one end portion of the optical fiber 11. The laser light incident on the optical fiber 11 propagates through the optical fiber 11 and is emitted from the other end of the optical fiber 11.

  Next, the configuration of the semiconductor laser 10 provided in the semiconductor laser module 1 of the present embodiment will be described.

  As shown in FIG. 3, the semiconductor laser 10 includes, for example, an n-type cladding made of n-type InGaAsP (indium gallium arsenic / phosphorus) on an n-type semiconductor substrate 31 made of n-type InP (indium / phosphorus). A layer 32, an optical separation and confinement (SCH) layer 33 made of InGaAsP, an active layer 34 made of InGaAsP, an SCH layer 35 made of InGaAsP, and a p-type cladding layer 36 made of p-type InP are sequentially stacked. Being done.

  In FIG. 3, an n-type clad layer 32, an SCH layer 33, an active layer 34, an SCH layer 35, and a p-type clad layer 36 constitute a mesa type optical waveguide, on both sides of the mesa type optical waveguide. A lower buried layer 37 made of p-type InP and an upper buried layer 38 made of n-type InP are formed.

  A p-type cladding layer 36 made of p-type InP is formed on the upper side of the SCH layer 35 and on the upper surface of the upper buried layer 38. A p-type contact layer 39 made of p-type InGaAsP is formed on the upper surface of the p-type cladding layer 36. Is formed. Further, a p-type metal electrode 40 is provided on the upper surface of the p-type contact layer 39. An n-type metal electrode 41 is provided on the lower surface of the n-type semiconductor substrate 31.

  Further, dielectric films (not shown) each having a predetermined reflectance are applied to the light emitting end faces 42 a and 42 b formed by cleaving the semiconductor laser 10.

  As shown in the enlarged sectional view of FIG. 4, the active layer 34 has a multiple quantum well (MQW) structure in which well layers 34a and barrier layers 34b are repeatedly and alternately stacked. That is, the active layer 34 has a plurality of barrier layers 34b and a number of well layers 34a that is one less than the number of the plurality of barrier layers 34b. Alternatively, the active layer 34 may have a single quantum well (SQW) structure in which one well layer 34a is sandwiched between two barrier layers 34b.

  Further, the SCH layer 33 located below the active layer 34 has a multilayer structure composed of a plurality of layers 33a, 33b, and 33c. Similarly, the SCH layer 35 located above the active layer 34 has a multilayer structure composed of a plurality of layers 35a, 35b, and 35c.

Here, the refractive index of the barrier layer 34b in the active layer 34 _n s, a refractive index _n a of the n-type cladding layer 32, the refractive index of the p-type cladding layer 36 and _{n b.} Further, the refractive indexes and thicknesses of the layers 33a, 33b, and 33c constituting the SCH layer 33 are n ₁ , n ₂ , n ₃ , t ₁ , t ₂ , and t ₃ , respectively, and the SCH layer 35 is similarly configured. The refractive indexes and thicknesses of the respective layers 35a, 35b, and 35c are assumed to be n ₁ , n ₂ , n ₃ , t ₁ , t ₂ , and t ₃ .

Then, the magnitude of each refractive index, as shown in FIG. 5, is set to be smaller enough away from the active layer 34, and a refractive index _{n a} of the n-type cladding layer 32 made of InGaAsP is made of InP higher than the refractive index _{n b} of the p-type cladding layer 36.

n _s > n ₁ > n ₂ > n ₃ > n _a > n _b

  Further, in this semiconductor laser 10, as shown in FIG. 5, the refractive index difference between adjacent layers constituting each SCH layer 33, 35 is changed from the active layer 34 to the n-type cladding layer 32 and the p-type cladding layer. It is set to become smaller as it goes to 36 respectively.

That is,
n _s −n ₁ > n ₁ −n ₂ > n ₂ −n ₃ > n ₃ −n _b > n ₃ −n _a
It is set to become.

The thicknesses t ₁ , t ₂ , and t ₃ of the layers 33a, 33b, 33c, 35a, 35b, and 35c constituting the SCH layers 33 and 35 are set to be equal.

  In the semiconductor laser 10 configured as described above, when a DC voltage is applied between the p-type metal electrode 40 and the n-type metal electrode 41, the laser light P is generated in the active layer 34, and the laser light P is generated. The light is emitted from the light emitting end faces 42a and 42b of the semiconductor laser 10 shown in FIG.

  In this case, as shown in the refractive index characteristics of FIG. 5, the refractive index difference between adjacent layers constituting the SCH layers 33 and 35 is changed from the active layer 34 to the n-type cladding layer 32 and the p-type cladding layer 36, respectively. In the SCH layers 33 and 35, the refractive index is drastically decreased in the high refractive index region in the vicinity of the active layer 34 in the SCH layers 33 and 35, so that the n-type cladding layer 32 and the p-type cladding layer In the region having a low refractive index in the region near the layer 36, the refractive index slowly decreases.

  For this reason, the concentration of light within the optical waveguide can be relaxed, that is, the optical confinement factor can be lowered, and the internal loss is reduced.

The refractive index _{n a} of the n-type cladding layer 32 made of InGaAsP is higher than the refractive index _{n b} of the p-type cladding layer 36 made of InP, the light intensity distribution of the light emitted from the semiconductor laser 10, the active layer 34 It becomes asymmetric in the center layer thickness direction. More specifically, the light intensity distribution is a characteristic A (see FIG. 6) with respect to a symmetrical characteristic A ′ (see FIG. 6) when the n-type cladding layer 32 and the p-type cladding layer 36 have the same refractive index. Thus, the distribution is biased toward the n-type cladding layer 32 side.

  For this reason, an increase in light loss due to light absorption between valence bands in the p-type cladding layer 36 can be suppressed, and high-power laser light can be obtained.

  The semiconductor laser 10 configured as described above is fixed to the upper stage portion 13b of the semiconductor laser module 1 by a junction down via the chip carrier 21.

  The semiconductor laser exhibiting an asymmetric light intensity distribution in the layer thickness direction is not limited to the InP-based buried type semiconductor laser having a clad structure with an asymmetric refractive index distribution as described above. A GaAs (gallium arsenide) ridge type or buried ridge type semiconductor laser having an asymmetric cladding structure may be used.

Next, the structure of the principal part of the semiconductor laser module 1 of the present embodiment will be described.
As shown in FIG. 7, the lens 12 has an optical surface 12 a that faces the semiconductor laser 10 and an optical surface 12 b that faces the optical fiber 11. The optical surface 12a has an aspherical shape, and the optical surface 12b has a substantially spherical shape. As such a lens 12, an aspherical lens on the market can be used.
The optical surface 12b may be aspherical.

  7 shows a configuration in which the lens 12 is composed of one lens, the lens 12 may have a configuration of a two-lens system. In this case, the optical surface on the side facing the semiconductor laser 10 of the lens closer to the semiconductor laser 10 only needs to be aspherical.

  The optical axis of the semiconductor laser 10 and the optical axis of the lens 12 are not parallel to each other but intersect each other at a predetermined angle θ. As shown in FIG. 7, the optical axis of the lens 12 is inclined with respect to the optical axis of the semiconductor laser 10 toward the side with a small bias of the asymmetric light intensity distribution in the direction toward the semiconductor laser 10.

  Since the shape of the optical surface 12a of the lens 12 is an aspherical shape, the laser beam incident on the optical surface 12a of the lens 12 from the semiconductor laser 10 is relaxed if the predetermined angle θ is appropriately selected. The light is emitted from the optical surface 12 b of the lens 12. Then, the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 is improved when the laser light with relaxed asymmetry is incident on the optical fiber 11.

  Therefore, the angle θ is set such that the laser light having an asymmetric light intensity distribution incident on the optical surface 12 a of the lens 12 from the semiconductor laser 10 is shaped in the Z-axis direction around the optical axis of the optical fiber 11. It is desirable that the angle is emitted from the optical surface 12b. As a specific configuration, as shown in FIG. 1, the optical axis of the semiconductor laser 10 is inclined with respect to the optical axis of the lens 12 by setting the inclination angle of the inclined surface 13 a of the substrate 13 to the XY plane as θ.

  Further, the applicant of the present application has determined that the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 when the emission point of the laser beam of the semiconductor laser 10 is arranged on the extension of the optical axis of the optical fiber 11 in the configuration of FIG. It has been confirmed through experiments that the value is good. In FIG. 7, the center point of the lens 12 is also arranged on the extension line of the optical axis of the optical fiber 11. However, this configuration is an example, and it is not always necessary to use such a configuration.

  FIG. 8 shows an example of the relationship between the coupling loss between the semiconductor laser 10 and the optical fiber 11 and the angle θ. From the graph of FIG. 8, it can be confirmed that the coupling loss is reduced by increasing the angle θ from 0 (zero) degree, and the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 is improved.

Although not shown in the graph of FIG. 8, the minimum coupling loss angle theta, the angle theta ₀ obtained maximum coupling efficiency in other words there. The angle θ _{0 at} this time is an angle at which the light intensity distribution of the laser light emitted from the optical surface 12 b of the lens 12 is most symmetric with respect to the optical axis of the optical fiber 11.

  The inclined surface 13a shown in FIG. 1 is inclined upward in the YZ plane, but the inclination direction of the inclined surface 13a is not limited to this, and the direction of the bias of the emitted light of the semiconductor laser 10 is not limited to this. Depending on the aspherical shape of the optical surface 12 a of the lens 12, there may be a case where the lens 12 is inclined downwardly in the YZ plane.

  Furthermore, in place of the semiconductor laser 10 shown in FIG. 3 and the like, when a semiconductor laser that emits laser light having a light intensity distribution asymmetric in the horizontal direction (X-axis direction) is installed in the semiconductor laser module 1, an inclined surface is used. The inclination direction of 13a may be inclined upward or downward in the XZ plane.

  Here, as a semiconductor laser that emits laser light having an asymmetric light intensity distribution in the horizontal direction (X-axis direction), for example, when the optical axis of the optical waveguide is 0 (zero) degree with respect to the normal of the light emitting end face A semiconductor laser having a slanted end surface that makes no angle.

  1 shows an example in which the inclined surface 13a is provided on the substrate 13, the inclined surface may be provided on the chip carrier 21 with the upper surface of the substrate 13 being parallel to the XY plane. Alternatively, inclined surfaces may be provided on both the substrate 13 and the chip carrier 21.

  As described above, the semiconductor laser module 1 of the present embodiment has an asymmetric light intensity distribution by tilting the optical axis of the semiconductor laser 10 with respect to the optical axis of the lens 12 having the aspherical optical surface 12a. The coupling efficiency between the semiconductor laser 10 emitting laser light and the optical fiber 11 can be improved.

  As the lens 12 that optically couples the semiconductor laser 10 and the optical fiber 11, an aspherical lens that is available on the market can be used. Therefore, the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 is low and simple. Can be improved.

(Second Embodiment)
Next, a semiconductor laser module 2 as a second embodiment of the present invention will be described with reference to the drawings. Note that the description of the same configuration and operation as in the first embodiment will be omitted as appropriate.

  As shown in FIG. 9, the semiconductor laser module 2 of the present embodiment includes one upper stage portion 53 b that fixes the semiconductor laser 10 via a chip carrier 21 and two lower stages, instead of the substrate of the first embodiment. A substrate 53 having portions 53c and 53d is provided.

  The upper surface 53a of the upper stage portion 53b is parallel to the XY plane, and the optical axis of the semiconductor laser 10 disposed thereon is also parallel to the XY plane. Here, the upper stage portion 53 b of the substrate 53 constitutes a support member that supports the semiconductor laser 10. One end surface of the upper stage portion 53b of the substrate 53 is in contact with one end surface 23a, 24a of the pair of abutting blocks 23, 24.

  As shown in FIGS. 9 and 10, the lens holder 22 that holds the lens 12 has the other of the pair of abutting blocks 23 and 24 at an arbitrary position P on the edge of the end surface 22 a orthogonal to the optical axis of the lens 12. The end faces 23b and 24b are fixed with solder, welding or adhesive.

Next, the structure of the principal part of the semiconductor laser module 2 of the present embodiment will be described.
As shown in FIG. 11, the optical axis of the semiconductor laser 10 and the optical axis of the lens 12 are not parallel to each other but intersect each other at a predetermined angle θ. As in the first embodiment, the optical axis of the lens 12 is inclined with respect to the optical axis of the semiconductor laser 10 to the side where the light intensity distribution that is asymmetric in the direction toward the semiconductor laser 10 is small. Further, the angle θ is set such that the laser light having an asymmetric light intensity distribution incident on the optical surface 12 a of the lens 12 from the semiconductor laser 10 is shaped in the Z-axis direction around the optical axis of the optical fiber 11. Is set to an angle emitted from the optical surface 12b.

  Specifically, as shown in FIG. 9, the angle formed by the end surface 22a of the lens holder 22 with respect to the other end surfaces 23b, 24b of the abutting blocks 23, 24 is set to θ, so that the optical axis of the lens 12 is changed. It is tilted with respect to the optical axis of the semiconductor laser 10.

  In the semiconductor laser module 2 configured as described above, by tilting the optical axis of the lens 12 having the aspherical optical surface 12a with respect to the optical axis of the semiconductor laser 10, as in the first embodiment, The coupling efficiency between the optical fiber 11 and the semiconductor laser 10 that emits laser light having an asymmetric light intensity distribution can be improved.

  In the present embodiment, the optical axis of the semiconductor laser 10 is parallel to the XY plane, but the upper surface 53a of the substrate 53 is an inclined surface, and the optical axis of the semiconductor laser 10 is changed as in the first embodiment. You can tilt it. Further, the chip carrier 21 may be provided with an inclined surface. Alternatively, inclined surfaces may be provided on both the substrate 53 and the chip carrier 21.

  In the present embodiment, the end surface 22a of the lens holder 22 is orthogonal to the optical axis of the lens 12. However, the present invention is not limited to this configuration, and the normal of the end surface 22a and the direction of the optical axis of the lens 12 do not match. The lens 12 may be fixed in the lens holder 22 in a state.

(Third embodiment)
Next, a semiconductor laser module 3 as a third embodiment of the present invention will be described with reference to the drawings. Note that description of the configuration and operation similar to those of the first and second embodiments will be omitted as appropriate.

  FIG. 12 is a side view showing the configuration of the semiconductor laser module 3 of the present embodiment. Similar to the second embodiment, the substrate 53 is formed of one upper step portion 53b for fixing the semiconductor laser 10 via the chip carrier 21 and two lower step portions 53c and 53d. The upper surface 53a of the upper stage portion 53b is parallel to the XY plane, and the optical axis of the semiconductor laser 10 disposed thereon is also parallel to the XY plane. Here, the upper stage portion 53 b of the substrate 53 constitutes a support member that supports the semiconductor laser 10.

  As shown in FIGS. 12 and 13, the semiconductor laser module 3 of the present embodiment has one end faces 63 a and 64 a parallel to the XZ plane, instead of the butting blocks of the first and second embodiments, Abutting blocks 63 and 64 having other end surfaces 63b and 64b as inclined surfaces having a predetermined angle θ with respect to the one end surfaces 63a and 64a are provided.

  Here, one end surface of the upper stage portion 53b of the substrate 53 is in contact with one end surface 63a, 64a of the butting block 63, 64. As shown in FIGS. 12 and 13, the lens holder 22 that holds the lens 12 is in a state in which the end face 22 a orthogonal to the optical axis of the lens 12 is in contact with the other end faces 63 b and 64 b of the abutting blocks 63 and 64. Thus, the other end faces 63b and 64b are fixed with solder, welding or adhesive. The optical axis of the semiconductor laser 10 passes between the pair of abutting blocks 63 and 64.

  Since the abutting blocks 63 and 64 have the inclined surfaces 63b and 64b, as shown in FIGS. 12 and 13, the optical axis of the semiconductor laser 10 and the optical axis of the lens 12 are not parallel to each other but at a predetermined angle. intersect at θ. Similar to the first and second embodiments, this angle θ is such that the laser light having an asymmetric light intensity distribution incident on the optical surface 12 a of the lens 12 from the semiconductor laser 10 is centered on the optical axis of the optical fiber 11. The angle is set at an angle that is shaped in the Z-axis direction and emitted from the optical surface 12b of the lens 12.

  The semiconductor laser module 3 configured as described above is different from the first and second embodiments by tilting the optical axis of the lens 12 having the aspherical optical surface 12 a with respect to the optical axis of the semiconductor laser 10. Similarly, the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 can be improved.

  In the present embodiment, the optical axis of the semiconductor laser 10 is parallel to the XY plane, but the upper surface 53a of the substrate 53 is an inclined surface, and the optical axis of the semiconductor laser 10 is changed as in the first embodiment. You can tilt it. Further, the chip carrier 21 may be provided with an inclined surface. Alternatively, inclined surfaces may be provided on both the substrate 53 and the chip carrier 21.

  In the present embodiment, the end surface 22a of the lens holder 22 is orthogonal to the optical axis of the lens 12. However, the present invention is not limited to this configuration, and the normal of the end surface 22a and the direction of the optical axis of the lens 12 do not match. The lens 12 may be fixed in the lens holder 22 in a state.

(Fourth embodiment)
In the first to third embodiments, the butterfly type has been described as an example of the semiconductor laser module. However, the present invention is not limited to this, and the semiconductor laser module may be a coaxial type. Hereinafter, a coaxial semiconductor laser module 4 according to a fourth embodiment of the present invention will be described with reference to the drawings. In addition, about the structure and operation | movement similar to 1st-3rd embodiment, description is abbreviate | omitted suitably.

  As shown in FIGS. 14 and 15, the semiconductor laser module 4 of the present embodiment includes a CAN package 72 that is used while being fixed to a bottom plate 71, and an optical fiber 11 into which laser light emitted from the CAN package 72 is incident. Prepare mainly.

  The outer shape of the CAN package 72 is formed by a disc-shaped stem 74 in which three leads 73 protrude toward the back side, and a hollow and cylindrical cap 75 fixed to the front side of the stem 74. The

  As shown in FIG. 15, in the cap 75, the semiconductor laser 10, a holding block 76 extending from the stem 74 and supporting and fixing the semiconductor laser 10, and between the semiconductor laser 10 and the holding block 76 are included. A chip carrier 77 to be arranged, a lens 12 for coupling the laser light emitted from the semiconductor laser 10 to the optical fiber 11, and a photodiode (not shown) for receiving the laser light from the semiconductor laser 10 are housed. Yes.

  Here, the holding block 76 constitutes a support member that supports the semiconductor laser 10. Although FIG. 15 shows a configuration in which the lens 12 is composed of one lens, the lens 12 may have a configuration of a two-lens system. In this case, the optical surface on the side facing the semiconductor laser 10 of the lens closer to the semiconductor laser 10 only needs to be aspherical.

  As shown in FIG. 14, the bottom plate 71 has a through hole 78 whose diameter gradually decreases from the back surface 71a side to the front surface 71b side. The CAN package 72 is disposed inside the through hole 78.

  The semiconductor laser module 4 further includes a holder 79 that connects the cap 75 of the CAN package 72 and the optical fiber 11, a sleeve 81 that fixes a cylindrical ferrule 80 attached to the tip of the optical fiber 11 to the holder 79, A CAN package 72, an optical fiber 11, a holder 79, and a cover 82 covering the sleeve 81.

  The holder 79 and the sleeve 81 are connected and fixed by welding. The cover 82 is connected and fixed to the bottom plate 71 with an adhesive. The ferrule 80 is fixed in the sleeve 81 by welding.

Next, the structure of the principal part of the semiconductor laser module 4 of the present embodiment will be described.
As shown in FIG. 15, the holding block 76 has an upper surface 76a as an inclined surface that forms a predetermined angle θ with respect to the XY plane. Since the holding block 76 has the inclined surface 76a, as shown in FIG. 7, the optical axis of the semiconductor laser 10 and the optical axis of the lens 12 do not cross each other but form a predetermined angle θ. Similar to the first to third embodiments, this angle θ is such that the laser light with an asymmetric light intensity distribution incident on the optical surface 12 a of the lens 12 from the semiconductor laser 10 is centered on the optical axis of the optical fiber 11. The angle is set at an angle that is shaped in the Z-axis direction and emitted from the optical surface 12b of the lens 12.

  The semiconductor laser module 4 configured as described above includes the first to third embodiments by tilting the optical axis of the semiconductor laser 10 with respect to the optical axis of the lens 12 having the aspherical optical surface 12a. Similarly, the coupling efficiency between the semiconductor laser 10 and the optical fiber 11 can be improved.

  In the present embodiment, the holding block 76 has the inclined surface 76a. However, the chip carrier 77 may be provided with an inclined surface with the upper surface of the holding block 76 parallel to the XY plane. Alternatively, both the holding block 76 and the chip carrier 77 may be provided with inclined surfaces.

1-4 Semiconductor laser module 10 Semiconductor laser 11 Optical fiber 12 Lens 12a, 12b Optical surface 13, 53 Substrate (support member)
13a, 76a Upper surface (inclined surface)
13b, 53b Upper part (support member)
13c, 13d, 53c, 53d Lower stage 14 Package (Housing)
21, 77 Chip carrier 22 Lens holder 22a End face 23, 24, 63, 64 Abutting block 23a, 24a, 63a, 64a One end face 23b, 24b The other end face 31 n-type semiconductor substrate 32 n-type cladding layer 33, 35, 33a, 33b, 33c, 35a, 35b, 35c SCH layer 34 active layer 36 p-type cladding layer 42a, 42b light emission end face 53a upper face 63b, 64b the other end face (inclined face)
76 Holding block (support member)

Claims (5)

A semiconductor laser (10) in which a plurality of semiconductor layers including the active layer (34) are stacked, an optical fiber (11), and a lens (12) that condenses emitted light from the semiconductor laser toward the optical fiber. And a semiconductor laser module (1, 2, 3, 4) comprising:
The light intensity distribution of the emitted light of the semiconductor laser is asymmetric in the layer thickness direction around the active layer,
The optical surface (12a) of the lens facing the semiconductor laser has an aspherical shape,
The optical axis of the lens is inclined with respect to the optical axis of the semiconductor laser in a direction toward the semiconductor laser toward a small bias side of the asymmetric light intensity distribution, and the optical axis of the semiconductor laser and the lens The optical axes intersect with each other at a predetermined angle, not parallel to each other ,
The predetermined angle is such that a light intensity distribution of light incident on the optical surface of the lens facing the semiconductor laser from the semiconductor laser is shaped in a direction perpendicular to the optical axis direction of the optical fiber, and the optical surface The semiconductor laser is characterized in that the light incident on the optical fiber is set so that the asymmetry with respect to the optical axis of the optical fiber is relaxed and emitted from the optical surface (12b) of the lens facing the optical fiber. module. A support member (13, 76) for supporting the semiconductor laser;
The support member has inclined surfaces (13a, 76a) for supporting the semiconductor laser in a state where the optical axis of the semiconductor laser and the optical axis of the lens intersect each other at the predetermined angle. The semiconductor laser module according to claim 1. An abutting block (23, 24) in which one end face (23a, 24a) and the other end face (23b, 24b) are formed in parallel with each other;
A support member (53) that supports the semiconductor laser and abuts the one end surface of the abutting block at one end surface;
A lens holder (22) for holding the lens and having an end surface (22a) intersecting the optical axis of the held lens;
The lens holder has the abutment block at an edge of the end surface that intersects the optical axis of the lens in a state where the optical axis of the semiconductor laser and the optical axis of the lens intersect at the predetermined angle. The semiconductor laser module according to claim 1, wherein the semiconductor laser module is fixed to the other end face of the semiconductor laser module. An abutment block (63, 64) having one end face (63a, 64a) and the other end face (63b, 64b);
A support member (53) that supports the semiconductor laser and abuts the one end surface of the abutting block at one end surface;
A lens holder (22) that holds the lens and has an end face (22a) that intersects the optical axis of the held lens, and is fixed in contact with the other end face of the abutting block at the end face; Further comprising
The other end surface of the abutting block has inclined surfaces (63b, 64b) for fixing the lens holder in a state where the optical axis of the semiconductor laser and the optical axis of the lens intersect each other at the predetermined angle. The semiconductor laser module according to claim 1, wherein: The semiconductor laser is
An active layer (34), an n-type cladding layer (32) made of InGaAsP sandwiching the active layer, and a p-type cladding layer (36) made of InP are provided on a substrate (31) made of InP. The semiconductor laser module according to any one of claims 1 to 4.