JP2006269567A - Semiconductor laser, optical transmitting module, and optical transmitting/receiving module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance high speed modulation performance while ensuring a sufficiently long lifetime in an AlGaInP based semiconductor laser. <P>SOLUTION: In the semiconductor laser, a first conductivity type clad layer 20, a semiconductor active layer 30, second conductivity type clad layers 51, 54, 56, a second conductivity type contact layer 60, and a second conductivity type electrode 72 are formed sequentially on the upper surface of a first conductivity type semiconductor substrate 10, a first conductivity type electrode 71 is formed below the first conductivity type clad layer 20, at least one of the second conductivity type clad layers 51, 54, 56 has a ridge structure and arranged such that a current is injected selectively into a specific region 30a of the semiconductor active layer 30, an AlGaInP based semiconductor laser element 2 having laser resonator length of 500 μm or above is provided, and the semiconductor substrate 10 side of the semiconductor laser element 2 is secured to a packaging substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device, an optical transmission module and an optical transmission / reception module using the semiconductor laser device, and more particularly to a semiconductor laser device mounted on a mounting substrate having a drive circuit for driving a semiconductor laser element.

  With the widespread use of optical fiber networks, low cost plastic optical fibers (POF) are widely used from silica based optical fibers. The current POF communication speed is about 100 Mbps, but higher speed has been demanded in order to increase the amount of transmission information. As a POF light source, an AlGaInP-based semiconductor laser element having a wavelength of 650 nm, which is a low loss wavelength region of POF, is considered.

  In order to improve the high-speed modulation property of the AlGaInP-based semiconductor laser device, a first p-type cladding layer provided on the semiconductor active layer, an n-type current blocking layer provided thereon, and an opening for current confinement A current confinement portion having a reverse bias structure with the formed second p-type cladding layer is provided, and a p-type contact layer is disposed on the current confinement portion, and the surface of the p-type contact layer is directed to the semiconductor substrate. A device structure has been proposed in which a pair of current confinement grooves that have been drilled and penetrated through the current blocking layer are provided across the current confinement opening portion to reduce the substantial reverse bias pn junction capacitance of the current confinement portion (Patent Document 1). ).

The semiconductor laser element is used in the form of a semiconductor laser device mounted on a mounting substrate having a drive circuit for driving the semiconductor laser element. Conventionally, AlGaInP-based semiconductor laser elements have been developed on the premise of a so-called junction down system in which a p-type electrode side (junction side) is fixed and mounted on a mounting substrate. This is because the heat resistance of the AlGaInP material is high and the heat dissipation is poor, so that the p-type electrode side, which is the heat dissipation side, is fixed to the heat sink of the mounting substrate to improve the heat dissipation.
Japanese Patent No. 2746131

  Although the semiconductor laser element described in Patent Document 1 is effective in improving high-speed modulation, it is not sufficient, and an AlGaInP-based semiconductor laser device capable of high-speed modulation in the GHz band or higher has not been realized. For optical communication applications, it is important to have a long life span of, for example, 80,000 hours or more. However, high-speed modulation properties and long life span are contradictory properties, and it is difficult to achieve both of them.

  The present invention has been made in view of such circumstances, and an AlGaInP-based semiconductor laser device capable of improving high-speed modulation while ensuring a sufficiently long life, an optical transmission module and an optical transmission / reception using the same The purpose is to provide modules.

  The semiconductor laser device according to the present invention includes a first conductivity type cladding layer, a semiconductor active layer, one or more second conductivity type cladding layers, and a first conductivity type semiconductor layer on one surface of the first conductivity type semiconductor substrate. Two-conductivity type contact layers and second-conductivity-type electrodes are sequentially provided, the first-conductivity-type electrodes are provided below the first-conductivity-type clad layer, and at least one second-conductivity-type clad layer has a ridge structure And an AlGaInP-based semiconductor laser element having a laser cavity length of 500 μm or more, wherein the current is selectively injected into a specific region of the semiconductor active layer. (The side opposite to the second conductivity type electrode) is mounted on a mounting board.

  In the present specification, “first conductivity type” and “second conductivity type” indicate semiconductor types such as p-type and n-type.

  In the semiconductor laser element forming the semiconductor laser device of the present invention, the first conductivity type electrode only needs to be formed below the first conductivity type cladding layer (on the opposite side to the second conductivity type electrode). The mold electrode and the second conductivity type electrode may be formed on different surfaces of the semiconductor substrate, or may be formed on the same surface.

  In the semiconductor laser device of the present invention, it is preferable that a laser resonator length of the semiconductor laser element is 2000 μm or less.

  In the semiconductor laser device of the present invention, since the semiconductor substrate side of the semiconductor laser element is fixed to the mounting substrate, the following structure can be adopted.

  That is, in the semiconductor laser device of the present invention, the semiconductor laser element has a current injection region of the semiconductor active layer extending in a band shape in the laser resonator axis direction, and the second conductivity type electrode faces the current injection region. A strip-shaped electrode body portion extending in the direction of the electrode body and a pad electrode portion connected to the side of the electrode body portion, the pad electrode portion being electrically connected to the driving circuit of the mounting substrate. it can.

  The semiconductor laser device of the present invention can be used as a light source for optical communication. For optical communication, the center wavelength of light emitted from the semiconductor laser element is in the range of 650 to 670 nm at 25 ° C. and 5 mW output. It is preferable.

  An optical transmission module according to the present invention includes the above-described semiconductor laser device according to the present invention and a plastic optical fiber that transmits light emitted from the semiconductor laser device.

  An optical transceiver module according to the present invention includes the above-described semiconductor laser device according to the present invention, a plastic optical fiber that transmits light emitted from the semiconductor laser device, and a light receiving element that receives the light emitted from the plastic optical fiber. It is characterized by that.

  In the semiconductor laser device of the present invention, a semiconductor laser device having a current confinement structure in which at least one of the plurality of second conductivity type cladding layers has a ridge structure and current is selectively injected into a specific region of the semiconductor active layer. Since the configuration is used, the parasitic capacitance of the semiconductor laser element is reduced.

  Furthermore, the semiconductor laser device of the present invention employs a junction up system in which the semiconductor substrate side of the semiconductor laser element is fixed to the mounting substrate. Therefore, unlike the junction down method in which the second conductivity type electrode is fixed to the mounting substrate, the degree of freedom in designing the second conductivity type electrode is high. Therefore, the entire area of the second conductivity type electrode can be reduced, for example, by forming the second conductivity type electrode in a pattern having an electrode main body portion and a pad electrode portion extending opposite to the current injection region. Since the entire area of the second conductivity type electrode can be reduced, the parasitic capacitance of the semiconductor laser element can be reduced.

  In the semiconductor laser device of the present invention, since the parasitic capacitance can be reduced by narrowing the area of the current confinement structure and the entire second conductivity type electrode, it is possible to improve the high-speed modulation performance as compared with the prior art. The present inventor has confirmed that a high-speed modulation property of a GHz band or higher, which has not been realized conventionally, can be realized.

  In the semiconductor laser device of the present invention, the laser cavity length of the semiconductor laser element is set to 500 μm or more, thereby ensuring a sufficiently long life (for example, 80,000 hours or more).

  Hereinafter, a semiconductor laser device according to an embodiment of the present invention, an optical transmission module and an optical transmission / reception module including the same will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a semiconductor laser device, FIG. 2 is an overall configuration diagram of an optical transmission module and an optical transmission / reception module (the semiconductor laser device is shown in a sectional view), and FIG. 3 is a semiconductor laser constituting the semiconductor laser device. FIG. 4 is an enlarged perspective view of the device, and FIG. 4 is a sectional view of the semiconductor laser device of FIG.

  The semiconductor laser device of this embodiment is an AlGaInP semiconductor laser device in which the center wavelength of emitted light is within a range of 650 to 670 nm (corresponding to a low-loss wavelength region of a plastic optical fiber) at 25 ° C. and 5 mW output, The element structure of the laser element and its mounting structure are characteristic.

  As shown in FIGS. 1 and 2, the semiconductor laser device 1 of the present embodiment is mounted on a mounting substrate 200 provided with a driving circuit for driving the semiconductor laser element 2. The mounting substrate 200 has a driving IC (Integrated Circuit) 220 including a driving circuit mounted on the surface of the chip carrier 210. The semiconductor laser element 2 and the driving IC 220 are electrically connected via a bonding wire 230. The semiconductor laser element 2 and the driving IC 220 are mounted on a heat sink 211 attached to the chip carrier 210. Although details will be described later, the semiconductor laser element 2 is mounted on the mounting substrate 200 by a so-called jack-up method.

  Examples of the material of the chip carrier 210 include Cu and CuW, and CuW is preferable. CuW and GaAs (the constituent material of the semiconductor substrate 10 to be described later) have substantially the same thermal expansion coefficient, and the strain at the time of mounting the semiconductor laser element 2 can be reduced. Examples of the material of the heat sink 211 include AlN, SiC, Si, and the like.

  In this embodiment, the optical transmission module 4 includes a semiconductor laser device 1 and a plastic optical fiber 310 that transmits light emitted from the semiconductor laser device 1. The optical transmission / reception module 5 includes the optical transmission module 4 and a light receiving element 320 that receives light emitted from the optical transmission module 4 (plastic optical fiber 310).

  The plastic optical fiber 310 is not particularly limited, and any type can be used. Specifically, both single-core and multi-core types can be used. The core diameter is arbitrary, and a single core having a diameter of, for example, 200 μm or more is preferably used. The composition is also arbitrary, and at least the core preferably contains a (meth) acrylic homopolymer and / or copolymer. The refractive index distribution of the core and the clad is also arbitrary, and any of a step index type and a graded index type can be used. The transmission mode is also arbitrary, and either single mode or multimode can be used. As the optical fiber 310, one having a small transmission loss with respect to the wavelength of light emitted from the semiconductor laser element 2 is preferably used. The light receiving element 320 is not particularly limited, and examples thereof include a photodiode.

  The mounting substrate 200 is mounted with a fiber holder 311 that holds the light incident end of the optical fiber 310, and the semiconductor laser element 2, the drive IC 220, the fiber holder 311, and the optical fiber 310 held by the fiber holder 311. The light incident end is housed in a sealing lid 240 attached to the mounting substrate 200 and hermetically sealed.

  The element structure of the semiconductor laser element 2 will be described in detail with reference to FIGS. In the present embodiment, an AlGaInP semiconductor laser element 2 having a current confinement structure is provided.

  The semiconductor laser element 2 injects a current into one surface (upper surface) of the n-type (first conductivity type) semiconductor substrate 10 upward from the semiconductor substrate 10 side into a specific region of the semiconductor active layer 30 and the semiconductor active layer 30. This is an element having a current confinement portion 50, a p-type (second conductivity type) contact layer 60, and a p-type electrode 72 in order, and an n-type electrode 71 on the other surface (lower surface) of the semiconductor substrate 10. . The semiconductor active layer 30 is sandwiched between the n-type cladding layer 20 and the p-type cladding layer 51, and the p-type cladding layer 51 of these two cladding layers forms part of the current confinement portion 50.

The semiconductor substrate 10 is made of n-GaAs, and an off-substrate whose crystal structure is inclined by 0 to 45 ° in the (111) direction from the (100) plane is preferably used, and the n-type cladding layer 20 is n-In _0.49 (Al _0.7 Ga _0.3 ) _0.51 P.

The semiconductor active layer 30 is a layer mainly composed of an i-type multi-quantum well active layer. In _0.49 (Al _0.5 Ga _0.5 ) _0.51 P guide layer / i-InGaP quantum from the semiconductor substrate 10 side. It has a multilayer structure of a multiple quantum well active layer / In _0.49 (Al _0.5 Ga _0.5 ) _0.51 P guide layer composed of a well layer and an i-AlGaInP barrier layer.

  The current confinement portion 50 is formed in the first p-type cladding layer 51, the n-type current blocking layer 53 formed thereon with the current confinement opening 53a, and the current confinement opening 53a. In addition, it has a reverse bias structure with the second p-type cladding layer 54. A p-type etching stop layer 52 is formed between the first p-type cladding layer 51 and the n-type current blocking layer 53.

  In the present embodiment, a p-type intermediate layer 55 is stacked on the second p-type cladding layer 54. The second p-type cladding layer 54 and the p-type intermediate layer 55 are formed only in the current confinement opening 53a of the current blocking layer 53, and the ridge structure portion 57 protruding from the etching stop layer 52 as a base is formed. There is no.

  As described above, the current confinement portion 50 includes the first p-type cladding layer 51, the etching stop layer 52, the n-type current blocking layer 53, the second p-type cladding layer 54, and the p-type intermediate layer 55. Yes. In the current confinement portion 50, a current selectively flows in the second p-type clad layer 54 having a ridge structure embedded in the current confinement opening 53 a, and below the second p-type clad layer 54. A current is selectively injected into the specific region 30a of the semiconductor active layer 30 located. Hereinafter, the specific region 30a is referred to as a current injection region.

  In the present embodiment, the current injection region 30a extends in a band shape in plan view in the laser resonator axis direction, and the second p-type cladding layer 54 and the intermediate layer 55 have the same shape along the shape of the current injection region 30a. It is formed in a shape (mesa band shape).

The first p-type cladding layer 51 is p-In _0.49 (Al _0.7 Ga _0.3 ) _0.51 P, and the p-type etching stop layer 52 is p-In _0.49 Ga _0.51 P, n The n-type current blocking layer 53 is n-GaAs, the second p-type cladding layer 54 is p-In _0.49 (Al _0.7 Ga _0.3 ) _0.51 P, and the p-type intermediate layer 55 is p-In _{0. .49} Ga _0.51 P.

  A third p-type cladding layer 56 and a p-type contact layer 60 are sequentially stacked on the current confinement portion 50, and both the layers 56 and 60 are made of p-GaAs.

  In the present embodiment, the contact layer 60 is excavated from the surface toward the semiconductor substrate 10 and penetrates the third p-type cladding layer 56, the current blocking layer 53, the first p-type cladding layer 51, and the semiconductor active layer 30. A pair of current confinement grooves 80 are provided with a current confinement opening 53a interposed therebetween. The p-type contact layer 60 is formed only between the pair of current confinement grooves 80.

A SiO ₂ dielectric insulating film 90 is formed in the region inside the pair of current confinement grooves 80 and on the third p-type cladding layer 56 except between the pair of current confinement grooves 80.

  The p-type electrode 72 is connected to the side of the electrode main body 72 a that extends opposite to the current injection region 30 a of the semiconductor active layer 30, and is bonded to the electrode main body 72 a. And a pad electrode portion 72b. The electrode body portion 72 a is formed between the pair of current confinement grooves 80, and the pad electrode portion 72 b is formed outside the pair of current confinement grooves 80.

  The semiconductor laser element 2 is designed to have a laser resonator length of 500 μm or more, preferably 500 μm or more and 2000 μm or less. By setting the laser resonator length in such a range, a sufficiently long lifetime (for example, 80,000 hours or more) is ensured. In addition, by setting the laser resonator length to 2000 μm or less, a particularly good high-speed modulation property can be obtained, and a high-speed modulation property in the GHz band or more can be realized (see “Example”).

  In the present embodiment, the semiconductor laser element 2 is mounted on the mounting substrate 200 by a junction up method. Specifically, the semiconductor substrate 10 side (n-type electrode 71 side) of the semiconductor laser element 2 is mounted and fixed to the mounting substrate 200 with solder or the like, and the pad electrode portion 72b of the p-type electrode 72 is driven via the bonding wire 230. Conducted to IC220.

  The semiconductor laser device 1 of the present embodiment, the optical transmission module 4 and the optical transmission / reception module 5 including the same are configured as described above.

  In the semiconductor laser device 1 of the present embodiment, the second p-type clad layer 54 of the plurality of p-type clad layers 51, 54, 56 has a ridge structure and is selectively applied to the specific region 30 a of the semiconductor active layer 30. Since the semiconductor laser element 2 having a current confinement structure into which current is injected is used, the parasitic capacitance of the semiconductor laser element 2 is reduced.

  In the present embodiment, in particular, a current confinement portion 50 having a reverse bias structure is provided on the semiconductor active layer 30 of the semiconductor laser element 2, and a pair of current confinement grooves are sandwiched between the current confinement openings 53 a included in the current confinement portion 50. 80 is provided. In such a configuration, current leakage to the outside of the pair of current confinement grooves 80 is blocked, and the substantial reverse bias pn junction surface is narrowed. Therefore, the reverse bias pn junction capacitance of the current confinement part 50 is reduced, and the parasitic capacitance is reduced.

  Furthermore, the semiconductor laser device 1 of the present embodiment employs a junction-up method in which the semiconductor substrate 10 side (n-type electrode 71 side) of the semiconductor laser element 2 is fixed to the mounting substrate 200. Therefore, unlike the junction down method in which the p-type electrode 72 is fixed to the mounting substrate 200, the design flexibility of the p-type electrode 72 is high. Therefore, as described above, the p-type electrode 72 can be formed in a pattern having the electrode main body portion 72a and the pad electrode portion 72b extending to face the current injection region 30a, and the area of the entire p-type electrode 72 can be reduced. Can be In this embodiment, since the area of the p-type electrode 72 is reduced, the parasitic capacitance of the semiconductor laser element 2 is reduced.

  In the semiconductor laser device 1 of the present embodiment, since the parasitic capacitance is reduced by the current confinement structure and the reduction of the entire area of the p-type electrode 72, the high-speed modulation performance is improved as compared with the conventional case. The present inventor has confirmed that high-speed modulation characteristics in the GHz band and higher, which have not been realized in the past, can also be realized (see “Example” section).

  In the semiconductor laser device 1 of this embodiment, the laser resonator length of the semiconductor laser element 2 is 500 μm or more, preferably 500 μm or more and 2000 μm or less. In the semiconductor laser device 1 of the present embodiment, since the junction-up mounting method is adopted, the heat dissipation of the AlGaInP material is inferior to that of the junction-down method, and the life tends to be reduced accordingly. However, the present inventor has found that by setting the laser resonator length within the above-mentioned range, sufficient long life (for example, 80,000 hours or more) can be secured under normal use conditions for optical communication applications (“implementation” See the Example section). In other words, the semiconductor laser device 1 of the present embodiment realizes high-speed modulation characteristics in the GHz band or higher while ensuring a sufficiently long life (for example, 80,000 hours or more).

  Since the optical transmission module 4 and the optical transmission / reception module 5 of the present embodiment use the semiconductor laser device 1 whose high-speed modulation property is improved while ensuring a long life as a light source, optical transmission and optical transmission / reception are performed at high speed. It can be implemented with high sensitivity and has a long life.

(Other aspects)
The semiconductor laser device, the optical transmission module and the optical transmission / reception module including the semiconductor laser device of the present invention are not limited to the above-described embodiments, and can be appropriately changed in design without departing from the spirit of the present invention.

  Only the embodiment provided with the semiconductor laser element having the current confinement groove has been described. However, the semiconductor laser element has a ridge structure in at least one of the plurality of p-type cladding layers, and a current is selectively supplied to a specific region of the semiconductor active layer. The same effect can be obtained by adopting a structure in which is injected.

  For example, as shown in FIG. 5, the p-type cladding layer is provided with only a p-type cladding layer 54 having a ridge structure extending in a belt shape in the axial direction of the laser resonator, and this p-type cladding layer 54 is not embedded in the current blocking layer 53. A p-type intermediate layer 55, a p-type contact layer 60, and a p-type electrode 72 are sequentially stacked on the type cladding layer 54, and a dielectric insulating film is formed on the etching stop layer 52 and in a region where the p-type cladding layer 54 is not formed. The same effect can be obtained even if the semiconductor laser element 3 on which 90 is formed is used. In the semiconductor laser element 3, there is no layer that may leak current on the side of the p-type cladding layer 54 having a ridge structure, and therefore no current confinement groove for blocking current leakage is provided. FIG. 5 is an enlarged perspective view corresponding to FIG. 3 of the above embodiment, and the same reference numerals are given to the same components.

  Also in the semiconductor laser element 3, since the p-type cladding layer 54 has a ridge structure and a current confinement structure in which current is selectively injected into a specific region of the semiconductor active layer 30, the parasitic capacitance is reduced. ing. In the semiconductor laser element 3, there is no layer that may leak current on the side of the p-type cladding layer 54 having the ridge structure, and therefore, the p-type cladding layer 54 is the same as the semiconductor laser element 2 having the current confining groove 80. Current leakage from side to side is cut off, and parasitic capacitance is reduced.

  Also in the case of using the semiconductor laser element 3, by adopting the junction-up method as in the above embodiment, the design flexibility of the p-type electrode 72 is high, and the electrode main body 72a and the pad electrode extending facing the current injection region The entire area of the p-type electrode 72 can be reduced, such as by forming a pattern having the portion 72b.

  As described above, even when the semiconductor laser element 3 is used, the parasitic capacitance is reduced by the current confinement structure and the reduction of the entire area of the p-type electrode 72, and the high-speed modulation property can be improved.

  Similarly to the above-described embodiment, the laser resonator length of the semiconductor laser element 3 is 500 μm or more, preferably 500 μm or more and 2000 μm or less, so that sufficient long life (for example, 80,000 hours or more) is ensured, and GHz is obtained. It is possible to realize a high-speed modulation property higher than the band.

  In the above-described embodiment, only the case where the n-type electrode 71 is formed on the lower surface of the semiconductor substrate 10 (the surface opposite to the side where the p-type electrode 72 is formed) has been described. The upper surface of the semiconductor substrate 10 may be provided below the clad layer 20.

  Next, examples and comparative examples according to the present invention will be described.

Example 1
The semiconductor laser device 2 shown in FIGS. 3 and 4 was produced. That is, the second p-type cladding layer 54 having a ridge structure is embedded in the current confinement opening 53a of the current blocking layer 53, and a pair of current confinement grooves 80 are provided across the current confinement opening 53a. The semiconductor laser device 2 was fabricated in which the mold electrode 72 was formed in a pattern having an electrode body portion 72a (width 30 μm) and a pad electrode portion 72b (width 100 μm). The element width was 500 μm, and the distance between the pair of current confinement grooves (constriction width) was 30 μm. The front end face of the semiconductor laser element shown in FIG. 3 is coated with a reflection film having a reflectance of 30%, and the rear end face is coated with a reflection film having a reflectance of 70%.

  Using the obtained semiconductor laser element 2, the semiconductor laser device 1 and the optical transmission / reception module 5 shown in FIGS. That is, the semiconductor substrate 10 side (n-type electrode 71 side) of the semiconductor laser element 2 is mounted and fixed to the heat sink 211 of the Cu chip carrier 210 by soldering (junction up method), and the pad electrode portion 72b and the drive IC 220 are wire bonded. Thus, the semiconductor laser device 1 was manufactured. Further, by using this semiconductor laser device 1, the optical transceiver module 5 shown in FIG. As the plastic optical fiber 310, a single core (core aperture 200 μm), step index type (multimode), and 100 m long optical fiber was used. A Si photodiode was used as the light receiving element 320.

(Comparative Example 1)
The p-type electrode has a pattern with no pad electrode part and an overall width of 300 μm, and the p-type electrode side is mounted and fixed to the heat sink of a copper chip carrier by soldering (junction down method), and the n-type electrode and the driving IC are wire bonded A semiconductor laser device for comparison and an optical transceiver module were manufactured in the same manner as in Example 1 except that the electrical conduction was performed.

(Evaluation)
For the semiconductor laser devices of Example 1 and Comparative Example 1, the lifetime and the modulation speed were evaluated by changing the resonator length. Further, the transmission characteristics of the optical transceiver module of Example 1 were evaluated. The evaluation method was as follows.

<Life> A life test of a single semiconductor laser element was performed under conditions of 50 ° C. and 5 mW continuous output, and MTTF (Mean Time To Failure) was measured.

<Modulation speed> The modulation characteristic of a small signal was evaluated, and the maximum value of the frequency at which the signal attenuated by 3 dB when the bias current was increased was determined as the modulation speed.

<Transmission characteristics> The bit error rate (BER) of the light received by the light receiving element and the waveform pattern when the semiconductor laser device was modulated at a speed of 2.4 Gbps with 5 mW output were evaluated.

(result)
The evaluation results of Example 1 and Comparative Example 1 are shown in FIG. As shown in the figure, when compared with the same resonator length, the modulation speed of the semiconductor laser device of Example 1 is improved by about 5 times compared with Comparative Example 1. The longer the resonator length, the more parasitic capacitance increases and the modulation band tends to decrease. However, in the semiconductor laser device of Example 1, high-speed modulation in the 1 GHz band is realized even at a resonator length of 2000 μm. High-speed modulation over the GHz band is realized in a wide range of the resonator length of 0 to 2000 μm.

  The semiconductor laser device of Example 1 has a shorter lifetime than that of Comparative Example 1, but a sufficiently long lifetime of MTTF of 80,000 hours or more is realized by setting the resonator length to 500 μm or more. Regardless of the mounting method, the lifetime increases as the resonator length increases under the driving conditions of 50 ° C. and 5 mW output. The present inventor has found that, with an AlGaInP-based semiconductor laser device, the degradation of the end face hardly becomes a problem at an output of about 5 mW, and the reliability greatly depends on the current density, and the lifetime is increased by increasing the resonator length and reducing the current density. I guess that will be realized.

When the transmission characteristics of the optical transceiver module of Example 1 were evaluated, the reception sensitivity was good even when the bit error rate in the received light was on the order of 10 ⁻⁹ , and the waveform pattern was a good pattern with a clear eye.

(Example 2)
A semiconductor laser element 3 of the type having no current blocking layer and current confinement groove shown in FIG. 5 was produced. The p-type electrode 72 was formed in a pattern having an electrode body portion (width 3 μm) and a pad electrode portion (width 100 μm). The element width was 300 μm. The front end face of the semiconductor laser device shown in FIG. 5 was coated with a reflection film having a reflectance of 40%, and the rear end face was coated with a reflection film having a reflectance of 80%.

  The semiconductor substrate side (n-type electrode side) of the obtained semiconductor laser element 3 is mounted and fixed to the heat sink of the CuW chip carrier by soldering (junction up method), and the pad electrode part and the driving IC are made conductive by wire bonding. A semiconductor laser device 1 was manufactured in the same manner as in Example 1. Using this semiconductor laser device, an optical transceiver module was fabricated in the same manner as in Example 1. The length of the plastic optical fiber was 30 m.

(Evaluation)
<Lifetime and Modulation Speed> With respect to the semiconductor laser device of Example 2, the cavity length was set to 2000 μm, and the life and modulation speed were evaluated (the evaluation method is the same as in Example 1 and Comparative Example 1).

<Transmission characteristics> The transmission characteristics of the optical transceiver module of Example 2 were evaluated. The bit error rate (BER) and the waveform pattern of the light received by the light receiving element when the semiconductor laser device was modulated at a speed of 1.0 Gbps with 5 mW output were evaluated.

(result)
The semiconductor laser device of Example 2 (resonator length 2000 μm) has a modulation speed of 1.0 GHz and a lifetime (MTTF) of 300,000 hours or more. Was realized. When the transmission characteristics of the optical transceiver module were evaluated, as in Example 1, the reception sensitivity was good even when the bit error rate in the received light was on the order of 10 ⁻⁹ , and the waveform pattern was a good pattern with a clear eye. It was.

  The semiconductor laser device, optical transmission module, and optical transmission / reception module of the present invention can be preferably used for applications that require high-speed modulation such as optical communication.

1 is a schematic perspective view of a semiconductor laser device according to an embodiment of the present invention. 1 is an overall configuration diagram of an optical transmission module and an optical transmission / reception module according to an embodiment of the present invention. 1 is an enlarged perspective view of a semiconductor laser element forming the semiconductor laser device of FIG. Sectional view of the semiconductor laser device of FIG. An enlarged perspective view showing another embodiment of the semiconductor laser element The figure which shows the evaluation result of Example 1 which concerns on this invention, and Comparative Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser apparatus 2, 3 Semiconductor laser element 4 Optical transmission module 5 Optical transmission / reception module 10 n-type semiconductor substrate (1st conductivity type semiconductor substrate)
20 n-type cladding layer (first conductivity type cladding layer)
30 Semiconductor active layer 30a Current injection region of semiconductor active layer 51, 54, 56 p-type cladding layer (second conductivity type cladding layer)
57 Ridge structure 60 p-type contact layer (second conductivity type contact layer)
71 n-type electrode (first conductivity type electrode)
72 p-type electrode (second conductivity type electrode)
72a Electrode body 72b Pad electrode 220 Drive IC (drive circuit)
200 mounting substrate 310 plastic optical fiber 320 light receiving element

Claims (6)

A first conductivity type cladding layer, a semiconductor active layer, one or a plurality of second conductivity type cladding layers, a second conductivity type contact layer, and a second layer are formed on one surface of the first conductivity type semiconductor substrate upward from the semiconductor substrate side. A first conductive type electrode under the first conductive type cladding layer, and at least one second conductive type cladding layer has a ridge structure, and the semiconductor active layer An AlGaInP-based semiconductor laser element having a laser cavity length of 500 μm or more, wherein a current is selectively injected into the specific region of
A semiconductor laser device, wherein the semiconductor substrate side of the semiconductor laser element is mounted on a mounting substrate.   2. The semiconductor laser device according to claim 1, wherein a laser cavity length of the semiconductor laser element is 2000 [mu] m or less.   In the semiconductor laser element, a current injection region of the semiconductor active layer extends in a band shape in the direction of the laser resonator axis, and the second conductive type electrode extends in a band-like electrode body portion and the electrode extending opposite to the current injection region 3. The device according to claim 1, further comprising a pad electrode portion provided on a side of the main body portion, wherein the pad electrode portion is electrically connected to a driving circuit of the mounting substrate. Semiconductor laser device.   4. The semiconductor laser device according to claim 1, wherein a center wavelength of light emitted from the semiconductor laser element is in a range of 650 to 670 nm at 25 ° C. and 5 mW output.   An optical transmission module comprising: the semiconductor laser device according to claim 1; and a plastic optical fiber that transmits light emitted from the semiconductor laser device.   5. A semiconductor laser device according to claim 1, a plastic optical fiber that transmits light emitted from the semiconductor laser device, and a light receiving element that receives light emitted from the plastic optical fiber. An optical transceiver module characterized by the above.

Images