JP2020035774A - Semiconductor laser module - Google Patents

Abstract

To provide a semiconductor laser module capable of materializing a high light-emission efficiency and a high output with a simple configuration.SOLUTION: The semiconductor laser module comprises: a semiconductor laser 10 in which an n-type semiconductor substrate, an active layer that emits light by injection of a drive current, and an n-type clad layer and a p-type clad layer that sandwich the active layer in a layer thickness direction are laminated and formed between a p-electrode and an n-electrode for injecting the drive current to the active layer; a package 17 storing the semiconductor laser 10; and an optical fiber 11 connected to the package 17 and configured to guide light emitted from an LR end surface to the exterior of the package 17. The n-electrode of the semiconductor laser 10 and a cathode terminal 18b of the package 17 are electrically connected with each other via a plurality of wires 47 wired in the n-electrode. The plurality of wires 47 are wired in the n-electrode within a range from a position of the LR end surface to a length of 2/10 to 6/10 of the whole length of the active layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor laser module, and more particularly to a semiconductor laser module having a semiconductor laser used as a light source for excitation of an erbium-doped fiber amplifier or a Raman amplifier.

  A semiconductor laser used as an excitation light source for an erbium-doped fiber amplifier (EDFA) or a Raman amplifier is required to have a high optical output.

  As shown in FIG. 13, the semiconductor laser 50 as described above has an n-type InGaAsP (indium-gallium-arsenic-phosphorus) on an n-type semiconductor substrate 31 made of n-type InP (indium / phosphorus). The type cladding layer 32, a light separation / 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 formed in this order. It is laminated.

  In FIG. 13, the n-type cladding layer 32, the SCH layer 33, the active layer 34, the SCH layer 35, and the p-type cladding layer 36 constitute a mesa-type optical waveguide, and are provided on both sides of the mesa-type optical waveguide. A buried layer 37 made of p-type InP and a buried layer 38 made of n-type InP are formed. The p-type cladding layer 36 made of p-type InP is formed on the upper side of the SCH layer 35 and the upper surface of the buried layer 38. On the upper surface of this p-type cladding layer 36, a p-type contact layer 39 made of p-type InGaAsP is Is formed. Further, on the upper surface of the p-type contact layer 39, a p-electrode 40 is provided. On the lower surface of the n-type semiconductor substrate 31, an n-electrode 41 is provided. The emission end face of the light generated in the active layer 34 is composed of an end face (LR end face) 42a provided with a low reflectivity film and an end face (HR end face) 42b provided with a high reflectivity film.

  In the above-described semiconductor laser 50, the light confinement coefficient in the active layer 34 and the SCH layers 33 and 35 is reduced in order to achieve high output. Furthermore, by biasing the light distribution toward the n-type cladding layer 32, light loss due to light absorption between valence bands in the p-type cladding layer 36 is suppressed.

  As a technique for further increasing the output of the semiconductor laser 50, while increasing the cavity length to improve the saturation output and increasing the reflectivity of the HR end face 42b, the reflectivity of the LR end face 42a is reduced. It is effective to improve the light extraction efficiency from the LR end surface 42a.

  The light intensity in the active layer 34 increases exponentially from the HR end face 42b toward the LR end face 42a, and when the active layer width is constant, the light intensity per unit area, that is, the light density similarly increases exponentially. I do. The light intensity I (z) at the position of the distance z from the HR end face 42b is calculated by using the light intensity I0 at the HR end face 42b, the internal gain g per unit length, and the internal loss α per unit length as I ( z) = I0exp {(g-α) .z}.

  However, when the light intensity increases toward the LR end surface 42a in this manner, the carrier density decreases accordingly, so that there is a shortage of carriers near the LR end surface 42a where the light intensity is large, and the light emission efficiency is reduced. As a countermeasure against this, it is effective to bias the injection current according to the light density in the semiconductor laser 50, and a method of dividing the p-electrode 40 or the n-electrode 41 and controlling the injection current amount has been proposed. (For example, see Patent Document 1).

Japanese Patent No. 3691507

  However, the method disclosed in Patent Literature 1 has a disadvantage that the manufacturing of a semiconductor laser and a current control method are complicated.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a semiconductor laser module capable of obtaining high luminous efficiency and high output with a simple configuration.

  In order to solve the above problems, a semiconductor laser module according to the present invention includes a semiconductor substrate, an active layer that generates light by injecting a drive current, an n-type clad layer sandwiching the active layer in a thickness direction, and a p-type. A cladding layer is formed between an upper electrode and a lower electrode for injecting the drive current into the active layer, and an emission end face of light generated in the active layer has an end face provided with a low reflectance film. A semiconductor laser comprising an end face provided with a high reflectivity film, a submount on which the semiconductor laser is mounted, a housing for storing the semiconductor laser and the submount, and connected to the housing; An optical fiber for guiding light emitted from the end face provided with the low reflectance film to the outside of the housing, and electrically connected to the upper surface electrode in the housing, from the outer surface of the housing. Protruding first end And a second terminal electrically connected to the lower surface electrode in the housing and protruding from an outer surface of the housing, wherein the drive current is supplied through the first terminal and the second terminal. In the semiconductor laser module to be supplied, the upper surface electrode and the first terminal are electrically connected via a plurality of wires wired to the upper surface electrode, and the plurality of wires are connected to the low reflectance. The end surface on which the film is formed is used as one end, and is wired to the upper surface electrode in a region from the one end to the other end separated by a predetermined distance, and the predetermined distance is 2/10 to 6/6 of the total length of the active layer. The configuration is in the range of 10 lengths.

  With this configuration, the semiconductor laser module according to the present invention shifts the wiring positions of the plurality of wires for injecting the driving current into the active layer toward the end face side of the semiconductor laser on which the low-reflectance film is formed, and By passing a large amount of drive current through the region where the light density is high, high luminous efficiency and high output can be obtained with a simple configuration.

  Further, in the semiconductor laser module according to the present invention, the submount has an electrode pattern electrically connected to an entire surface of the lower surface electrode and electrically connected to the second terminal. Is also good.

  Further, in the semiconductor laser module according to the present invention, the predetermined distance may be longer than 3/10 of the entire length of the active layer and shorter than 5/10. Good.

  With this configuration, the semiconductor laser module according to the present invention can efficiently increase the output light intensity while suppressing heat generation of the semiconductor laser due to an increase in the applied voltage.

  An object of the present invention is to provide a semiconductor laser module capable of obtaining high luminous efficiency and high output with a simple configuration.

FIG. 2 is a side view showing the configuration of the semiconductor laser module according to the embodiment of the present invention. FIG. 2 is a plan view illustrating a configuration of a semiconductor laser module according to an embodiment of the present invention. FIG. 2 is a perspective view of a semiconductor laser provided in the semiconductor laser module according to the embodiment of the present invention. FIG. 3 is a sectional view taken along line AA of FIG. 2. FIG. 4 is a diagram for explaining positions of wires wired to upper electrodes of a semiconductor laser included in the semiconductor laser module according to the embodiment of the present invention. 5 is a graph showing the drive current dependence of the optical output and applied voltage of the semiconductor laser provided in the semiconductor laser module according to the embodiment of the present invention. 7 is a graph in which a high current region in FIG. 6 is enlarged. 8 is a graph showing the dependence of the optical output and applied voltage on the current injection position when the drive current is 2.6 [A] in the graph of FIG. 7. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a main part of a semiconductor laser included in a semiconductor laser module according to an embodiment of the present invention. 5 is a graph showing a refractive index characteristic of a semiconductor laser provided in the semiconductor laser module according to the embodiment of the present invention. 6 is a graph showing light intensity distribution characteristics of emitted light of a semiconductor laser provided in the semiconductor laser module according to the embodiment of the present invention. FIG. 7 is a schematic cross-sectional view illustrating another configuration of the semiconductor laser provided in the semiconductor laser module according to the embodiment of the present invention. It is a perspective view of the conventional semiconductor laser.

  Hereinafter, embodiments of a semiconductor laser module according to the present invention will be described with reference to the drawings. Note that the dimensional ratio of each component on each drawing does not always match the actual dimensional ratio.

  As shown in FIGS. 1 and 2, a butterfly type semiconductor laser module 1 according to an embodiment of the present invention includes a semiconductor laser 10, an optical fiber 11 as a single mode optical fiber, a lens 12, and a light receiving element 13. , A thermistor 14, a heat dissipation board 15, and a Peltier element 16.

  The semiconductor laser 10, the lens 12, the light receiving element 13, the thermistor 14, the heat radiation board 15, and the Peltier element 16 are stored inside a hollow rectangular parallelepiped package (housing) 17.

  As shown in FIG. 3, the semiconductor laser 10 includes an n-type semiconductor substrate 31, an active layer 34 that generates light by injecting a drive current, an n-type clad layer 32 that sandwiches the active layer 34 in the layer thickness direction, and a p-type The cladding layer 36 is formed between the p-electrode 40 and the n-electrode 41 for injecting a drive current into the active layer 34. Further, the emission end face of the light generated in the active layer 34 includes an end face (LR end face) 42a provided with a low reflectivity film and an end face (HR end face) 42b provided with a high reflectivity film. The length of the active layer 34 of the semiconductor laser 10, that is, the distance between the LR end face 42a and the HR end face 42b is, for example, about 3 mm, and a specific range is 2.5 mm to 4.0 mm. The details of the configuration of the semiconductor laser 10 will be described later.

  The lens 12 condenses light (laser light) emitted from the LR end face 42 a of the semiconductor laser 10 toward the optical fiber 11. Although FIGS. 1 and 2 show a configuration in which the lens 12 is composed of one lens, the lens 12 may have a configuration of a two-lens system.

  The optical fiber 11 is connected to a wall surface 17 a on the front side of the package 17, and guides light collected by the lens 12 to the outside of the package 17.

  The light receiving element 13 is an element for receiving light slightly emitted from the HR end face 42b of the semiconductor laser 10 and monitoring the operation of the semiconductor laser 10.

  As shown in FIG. 2, a plurality of terminals 18 for inputting and outputting signals for controlling the operation of the semiconductor laser module 1 are attached to both side walls 17b and 17c of the package 17 at predetermined intervals. These terminals 18 can be soldered to an arbitrary pattern on a printed circuit board. Of the plurality of terminals 18, for example, terminals denoted by reference numerals 18a and 18b are an anode terminal 18a and a cathode terminal 18b for supplying a drive current to the semiconductor laser 10, respectively.

  The anode terminal (second terminal) 18 a is electrically connected to the p-electrode 40 as the lower surface electrode of the semiconductor laser 10 in the package 17 and protrudes from the outer surface of the side wall 17 c of the package 17. The cathode terminal (first terminal) 18 b is electrically connected to the n-electrode 41 as the upper surface electrode of the semiconductor laser 10 in the package 17 and protrudes from the outer surface of the side wall 17 c of the package 17.

  As shown in FIG. 1, a Peltier device 16 is fixed to the upper surface of a bottom wall 17d in the package 17. The heat dissipation board 15 is fixed on the Peltier element 16.

  The heat dissipation board 15 is made of, for example, a metal material such as copper tungsten (CuW) or copper, or aluminum nitride (AlN). An LD submount 19 on which the semiconductor laser 10 that emits laser light is mounted, a lens holder 20 that holds the lens 12, a PD submount 21 that supports the light receiving element 13, A relay board 22 for relaying between the mount 19 and the cathode terminal 18b is fixed. In this embodiment, an example in which copper tungsten (CuW) is used as the heat radiation substrate 15 is described. However, when aluminum nitride (AlN) is used as the heat radiation substrate 15, the surface of the heat radiation substrate 15 has high conductivity. It is to be used covered with a membrane.

  Further, as shown in FIG. 2, a thermistor 14 for detecting the temperature of the semiconductor laser 10 is fixed on the LD submount 19. The Peltier element 16 cools the heat radiation board 15 so that the temperature detected by the thermistor 14 becomes a predetermined temperature (for example, 25 ° C.).

  Further, a flange portion 23 is provided at a lower front end and a lower rear end of the package 17, and a mounting hole 24 for screwing the semiconductor laser module 1 to an arbitrary heat sink is provided in the flange portion 23.

  A cylindrical opening 25 for guiding laser light emitted from the LR end surface 42a of the semiconductor laser 10 to the outside is formed on a wall surface 17a of the package 17, and a window glass 26 is housed in the opening 25. Have been.

  A cylindrical ferrule 27 is attached to the tip of the optical fiber 11. The cylindrical ferrule 27 is fixed to a wall surface 17 a of the package 17 by a sleeve 28. Further, a cylindrical cover 29 surrounding the entire ferrule 27 and a part of the optical fiber 11 is fixed to the wall surface 17 a of the package 17.

  Here, the cover 29 is connected and fixed to the wall surface 17 a of the package 17. The ferrule 27 is fixed in the sleeve 28 by welding. Since the package 17, the sleeve 28, and the cover 29 are connected by welding, each is made of a metal material such as stainless steel (SUS).

  Next, a configuration of a main part of the semiconductor laser module 1 of the present embodiment will be described.

FIG. 4 is a sectional view taken along line AA of FIG. The LD submount 19 is made of an insulating material such as aluminum nitride (AlN) or silicon carbide (SiC), for example, and has two divided electrode patterns 19a and 19b formed on the upper surface. The relay board 22 is made of an insulating material such as AlN or alumina (Al ₂ O ₃ ), for example, and has an electrode pattern 22a formed on the upper surface.

  The semiconductor laser 10 is fixed on the LD submount 19 by junction down so that the n-electrode 41 becomes an upper electrode and the p-electrode 40 becomes a lower electrode, for example. In this case, the semiconductor laser 10 is die-bonded to the electrode pattern 19a via solder or the like so that the entire surface of the p-electrode 40 is electrically connected to the electrode pattern 19a of the LD submount 19. The entire surface of the p-electrode 40 is electrically connected to the heat dissipation board 15 via the electrode pattern 19a and the plurality of wires 45, and further to the anode terminal 18a by the plurality of wires 46 via the heat dissipation board 15, as shown in FIG. Electrically connected.

  On the other hand, the electrode pattern 19b of the LD submount 19 is electrically connected to the n-electrode 41 of the semiconductor laser 10 via a plurality of wires 47. The electrode pattern 19b is electrically connected to the electrode pattern 22a of the relay board 22 via a plurality of wires 48. Further, the electrode pattern 22a of the relay board 22 is electrically connected to the cathode terminal 18b via a plurality of wires 49. Thus, the n-electrode 41 of the semiconductor laser 10 and the cathode terminal 18b are electrically connected in the package 17. In addition, as the plurality of wires 45 to 49, for example, a gold wire, a silver wire, a copper wire, or the like can be used.

  FIG. 5 is a diagram illustrating an example of positions of a plurality of wires 47 wired to the n-electrode 41 as the upper surface electrode. FIG. 5A shows a case where ten wires 47 are bonded at substantially equal intervals throughout the length of the n-electrode 41. FIG. 5B shows a case where only the eight wires 47 on the LR end surface 42a side are bonded to the n-electrode 41 as compared with the example of FIG. 5A. FIG. 5C shows a case where only the six wires 47 on the LR end surface 42a side are bonded to the n-electrode 41 as compared with the example of FIG. 5A. FIG. 5D shows a case where only the four wires 47 on the LR end face 42a side are bonded to the n-electrode 41 as compared with the example of FIG. 5A. FIG. 5E shows a case where only two wires 47 on the LR end face 42a side are bonded to the n-electrode 41, as compared with the example of FIG. 5A.

  FIG. 6 shows the driving of the optical output and the applied voltage of the semiconductor laser 10 when the positions (specifically, the number of wires) of the plurality of wires 47 wired to the n-electrode 41 are changed as shown in FIG. It is a graph showing current dependency. FIG. 7 is an enlarged graph of the high current region of FIG. Here, the driving current on the horizontal axis represents the sum of the driving currents injected into the semiconductor laser 10 via the plurality of wires 47. That is, at a certain drive current, the smaller the number of wires bonded to the n-electrode 41, the greater the current injected into the semiconductor laser 10 per wire.

  FIG. 8 is a graph showing the dependence of the optical output and applied voltage on the current injection position (specifically, the number of wires) when the drive current is 2.6 [A] in the graph of FIG.

  As shown in the changes in FIGS. 5A to 5E, when the position where the plurality of wires 47 are bonded to the n-electrode 41 is shifted toward the LR end surface 42a, the applied voltage monotonously increases. It can be seen from the graph of FIG. It is considered that the increase in the applied voltage is due to the drive current flowing in the semiconductor laser 10 being biased toward the LR end surface 42a.

  Further, as shown in the changes in FIGS. 5A to 5D, when the position where the plurality of wires 47 are bonded to the n-electrode 41 is shifted toward the LR end surface 42a, the light output increases. It can be seen from the graph of FIG. For example, the light output when the number of wires is four is increased by about 4% as compared with the case where the number of wires is ten.

  However, when the number of wires bonded to the n-electrode 41 is reduced to two as shown in FIG. 5E, the light output is reduced as compared with the case where the number of wires is six as shown in the graph of FIG. Resulting in. This decrease in optical output is considered to be due to the influence of heat generation of the semiconductor laser 10 due to an increase in the applied voltage. The light output when the number of wires is two is increased by about 2.7% as compared with the case where the number of wires is ten.

  That is, the range in which the plurality of wires 47 are wired in the n-electrode 41 is a region from the one end to the other end separated by a predetermined distance when the LR end surface 42a is set as one end. The predetermined distance is preferably in the range of 2/10 to 6/10 of the total length of the active layer 34 (corresponding to 2 to 6 wires), and in particular, It is more preferable that the length is longer than 3/10 and shorter than 5/10 (corresponding to four wires).

  In the above description, the configuration in which the semiconductor laser 10 shown in FIG. 3 and the like is fixed on the LD submount 19 by junction down is taken as an example. However, the present invention is not limited to this. The semiconductor laser 10 may be fixed on the LD submount 19 by junction-up so that the upper surface electrode and the n-electrode 41 become lower surface electrodes.

  In this case, the p-electrode 40 and the anode terminal 18a as the first terminal are electrically connected via a plurality of wires wired to the p-electrode 40, an appropriately provided relay board, and the like. Further, the n-electrode 41 and the cathode terminal 18b as the second terminal are electrically connected via the electrode pattern 19a, the heat dissipation board 15, and the like. Similarly to the junction-down configuration, the range to which a plurality of wires are bonded in the p-electrode 40 is a region from the one end to the other end separated by a predetermined distance when the LR end surface 42a is set as one end. The predetermined distance is preferably in the range of 2/10 to 6/10 of the total length of the active layer 34 (corresponding to 2 to 6 wires), and in particular, It is more preferable that the length is longer than 3/10 and shorter than 5/10 (corresponding to four wires).

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

  As shown in FIG. 3, the semiconductor laser 10 has, for example, an n-type semiconductor substrate 31 made of n-type InP, an n-type cladding layer 32 made of n-type InGaAsP, a SCH layer 33 made of InGaAsP, and an active material made of InGaAsP. A layer 34, an SCH layer 35 made of InGaAsP, and a p-type clad layer 36 made of p-type InP are sequentially stacked. That is, the n-type cladding layer 32 and the p-type cladding layer 36 sandwich the active layer 34 in the layer thickness direction via the SCH layer 33 and the SCH layer 35, respectively.

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

  The p-type cladding layer 36 made of p-type InP is formed on the upper side of the SCH layer 35 and the upper surface of the buried layer 38. On the upper surface of the p-type cladding layer 36, a p-type contact layer 39 made of p-type InGaAsP is formed. Is formed. Further, on the upper surface of the p-type contact layer 39, a p-electrode 40 is provided. On the lower surface of the n-type semiconductor substrate 31, an n-electrode 41 is provided. The p-electrode 40 and the n-electrode 41 are electrodes for injecting a drive current into the active layer 34.

  The LR end face 42a and the HR end face 42b formed by cleavage of the semiconductor laser 10 are each provided with a dielectric film having a predetermined reflectance. As described above, the LR end face 42a is an end face provided with a low reflectance film, and the HR end face 42b is an end face provided with a high reflectance film.

  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, as shown in the enlarged cross-sectional view of FIG. That is, the active layer 34 includes a plurality of barrier layers 34b and a number of well layers 34a smaller by one 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.

  The SCH layer 33 located below the active layer 34 has a multilayer structure including a plurality of layers 33a, 33b, and 33c. Similarly, the SCH layer 35 located above the active layer 34 has a multilayer structure including a plurality of layers 35a, 35b, 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 respective layers 33a, 33b, 33c of the refractive index and thickness, respectively _{n 1, n 2, n 3} , t 1, t 2, t 3 constituting the SCH layer 33, similarly, constitute the SCH layer 35 each layer 35a, 35b, the refractive index and thickness of 35c and _{n 1, n 2, n 3} , t 1, t 2, t 3.

Then, the magnitude of each refractive index, as shown in FIG. 10, 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 the semiconductor laser 10, as shown in FIG. 10, the difference in the refractive index between the adjacent layers constituting each of the SCH layers 33 and 35 is different from the active layer 34 to the n-type cladding layer 32 and the p-type cladding layer. 36, it is set to be smaller as it goes toward each.

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 be.

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-electrode 40 and the n-electrode 41, laser light is generated in the active layer 34, and the laser light is applied to the semiconductor laser shown in FIG. The laser beam 10 is emitted outside from the LR end surface 42a and the HR end surface 42b.

  In this case, as shown in the refractive index characteristics of FIG. 10, the difference in the refractive index between the 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 sharply decreases in the high refractive index region near the active layer 34, and the n-type cladding layer 32 and the p-type cladding In the low refractive index region near the layer 36, the refractive index decreases slowly.

  Therefore, the degree of concentration of light in the optical waveguide can be reduced, that is, the light confinement coefficient can be reduced, and the internal loss decreases.

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 layer thickness direction with the center. More specifically, the light intensity distribution is different from the symmetric characteristic A ′ (see FIG. 11) when the n-type cladding layer 32 and the p-type cladding layer 36 have the same refractive index, and the characteristic A (see FIG. 11). As shown in FIG.

  For this reason, it is possible to suppress an increase in light loss due to light absorption between valence bands in the p-type cladding layer 36, and it is possible to obtain high-power laser light.

  Incidentally, the semiconductor laser 10 shown in FIG. 3 and the like has the respective layers formed on the n-type semiconductor substrate 31. However, as shown in FIG. 12, the respective layers are formed on the p-type semiconductor substrate 31 ′. The semiconductor laser 10 'may be used as the semiconductor laser of the semiconductor laser module 1 of the present embodiment. As for the semiconductor laser 10 ′, either a configuration fixed on the LD submount 19 by junction down or a configuration fixed by junction up is possible.

  The semiconductor laser 10 'shown in FIG. 12 includes a p-type cladding layer 36 made of p-type InP, a SCH layer 35 made of InGaAsP, and an active layer made of InGaAsP on a p-type semiconductor substrate 31' made of p-type InP. 34, an SCH layer 33 made of InGaAsP and an n-type clad layer 32 made of n-type InGaAsP are sequentially stacked.

  In FIG. 12, the p-type cladding layer 36, the SCH layer 35, the active layer 34, the SCH layer 33, and the n-type cladding layer 32 constitute a mesa-type optical waveguide, and are provided on both sides of the mesa-type optical waveguide. A buried layer 38 made of n-type InP and a buried layer 37 made of p-type InP are formed. Further, an n-electrode 41 is provided on the upper surface of the n-type cladding layer 32. Further, a p-electrode 40 is provided on the lower surface of the p-type semiconductor substrate 31 '.

  Also in the semiconductor laser 10 ′ of FIG. 12 configured as described above, the n-type cladding layer 32 is made of InGaAsP having a higher refractive index than the p-type cladding layer 36 made of InP, as shown in FIG. Similarly to the semiconductor laser 10, the light intensity distribution can be biased toward the n-type cladding layer 32.

  As described above, in the semiconductor laser module 1 according to the present embodiment, the wiring positions of the plurality of wires 47 for injecting the drive current into the active layer 34 are biased toward the LR end surface 42 a of the semiconductor laser 10, By supplying more drive current to the region where the laser 10 has a high light density, high luminous efficiency and high output can be obtained with a simple configuration.

  In the semiconductor laser module 1 according to the present embodiment, the range in which the plurality of wires 47 are wired to the upper surface electrode is a region from the one end to the other end separated by a predetermined distance when the LR end surface 42a is set as one end. is there. In particular, when the predetermined distance is longer than 3/10 of the total length of the active layer 34 and shorter than 5/10, the semiconductor laser module 1 according to the present embodiment is The output light intensity can be efficiently increased while suppressing heat generation of the semiconductor laser 10 due to an increase in the applied voltage.

REFERENCE SIGNS LIST 1 semiconductor laser module 10 semiconductor laser 11 optical fiber 12 lens 15 heat dissipation substrate 17 package 18 a anode terminal 18 b cathode terminal 19 LD submount 19 a, 19 b electrode pattern 22 relay substrate 22 a electrode pattern 31 n-type semiconductor substrate 31 ′ p-type semiconductor substrate 32 n-type cladding layer 34 active layer 36 p-type cladding layer 40 p-electrode 41 n-electrode 42a LR end face 42b HR end face 45-49 wire

Claims (3)

A semiconductor substrate (31, 31 '), an active layer (34) for generating light by injecting a drive current, and an n-type cladding layer (32) and a p-type cladding layer (36) sandwiching the active layer in the thickness direction. Are formed between an upper electrode (41, 40) and a lower electrode (40, 41) for injecting the drive current into the active layer, and the emission end face of light generated in the active layer has low reflection. A semiconductor laser (10) comprising an end face (42a) provided with a refractive index film and an end face (42b) provided with a high reflectivity film;
A submount (19) on which the semiconductor laser is mounted;
A housing (17) for storing the semiconductor laser and the submount;
An optical fiber (11) connected to the housing and for guiding light emitted from the end face provided with the low reflectance film to the outside of the housing;
A first terminal (18b, 18a) electrically connected to the upper surface electrode in the housing and protruding from an outer surface of the housing;
A second terminal (18a, 18b) that is electrically connected to the lower surface electrode in the housing and protrudes from an outer surface of the housing, and includes a second terminal (18a, 18b) via the first terminal and the second terminal. A semiconductor laser module (1) to which a driving current is supplied,
The upper surface electrode and the first terminal are electrically connected through a plurality of wires (47) wired to the upper surface electrode,
The plurality of wires are connected to the upper surface electrode in a region from the one end to the other end separated from the one end by a predetermined distance, with the end surface on which the low-reflectance film is provided being one end. A semiconductor laser module having a length in a range of 2/10 to 6/10 of a total length of the layer.   2. The semiconductor laser according to claim 1, wherein the submount has an electrode pattern electrically connected to an entire surface of the lower electrode and electrically connected to the second terminal. 3. module.   The semiconductor laser according to claim 1, wherein the predetermined distance is in a range longer than 3/10 and shorter than 5/10 of a total length of the active layer. 4. module.

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