JP2010003883A - Semiconductor laser device, optical module, and optical transceiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a horizontal-cavity surface emitting laser which emits laser light in a direction exactly perpendicular to a semiconductor substrate. <P>SOLUTION: By forming a surface emitting type horizontal-cavity surface emitting laser on a semiconductor substrate tilted at 9.7° in a [01 bar 1] direction from a (100) plane, an angle that a mirror forms with the surface of the substrate is made exactly 45°. Moreover, by forming a backside emitting type horizontal-cavity surface emitting laser on the semiconductor substrate tilted at 9.7° in a [011] direction from the (100) plane, an angle that a mirror forms with the surface of the substrate is made exactly 135°. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a technology effective when applied to a semiconductor laser element such as an optical communication laser and an optical disk laser, an optical module such as an optical transmission module and a CAN (CAN) module equipped with the semiconductor laser element, and an optical transceiver. It is about.

  Semiconductor lasers can be classified into three types: horizontal cavity surface emitting lasers, vertical cavity surface emitting lasers, and horizontal cavity surface emitting lasers, when classified according to the combination of the cavity direction and the laser beam emission direction.

  In the first horizontal cavity surface emitting laser, an optical waveguide is formed in a horizontal direction in a plane of a semiconductor substrate, and laser light is emitted from an end surface obtained by cleaving the substrate. This laser structure can make the resonator length as long as several hundred μm, and is suitable for obtaining a high light output, and is the most popular laser structure. However, when this structure is used, it is necessary to divide the substrate during the manufacturing process in order to form a laser reflecting mirror. For this reason, there is a demerit that the manufacturing process to the characteristic inspection cannot be performed consistently without dividing the semiconductor wafer, and the manufacturing cost increases.

  Next, the second vertical cavity surface emitting laser is a laser having a structure in which the resonator is formed in a direction perpendicular to the substrate. For this reason, since it is not necessary to divide the substrate to form the resonator, there is an advantage that laser production and characteristic inspection can be performed with a full wafer, and manufacturing costs can be reduced. However, this structure has a demerit that the resonator length is very short because it is determined by the crystal growth film thickness, and it is essentially difficult to obtain a high light output.

  On the other hand, the third horizontal cavity surface emitting laser has a laser structure that combines the advantages of the above two types of lasers. In this structure, the resonator is formed in a horizontal direction within the substrate surface, and further, reflectors inclined at 45 ° or 135 ° for emitting laser light from the front surface or the back surface of the substrate are integratedly formed. It has a structure. The present invention relates to an improved technique for such a horizontal cavity surface emitting laser.

  FIG. 1 shows an example of a structure of a horizontal cavity surface emitting laser of a type in which reflecting mirrors forming an angle of 45 ° with the substrate surface are integrated and light is emitted from the surface of the substrate. In this structure, since the laser light generated in the active layer 13 is totally reflected by the reflecting mirror 17 for surface emission having an angle of 45 ° with the surface of the substrate 12 and guided to the surface side of the substrate 12, Light is emitted from the surface.

  Next, FIG. 2 shows a structural example of a horizontal cavity surface emitting laser of a type in which reflecting mirrors forming an angle of 135 ° with the surface of the substrate 12 are integrated and light is emitted from the back surface of the substrate 12. In this structure, the laser light generated in the active layer 13 is totally reflected by the back-surface emitting reflecting mirror 19 that forms an angle of 135 ° with the surface of the substrate 12 and guided to the back surface side of the substrate 12. Light is emitted from the back surface.

  As for the details of the structure of the horizontal cavity surface emitting laser, a horizontal cavity surface emitting laser of the type in which reflecting mirrors inclined so as to form an angle of 135 ° with the surface of the substrate 12 is taken as an example. This will be described with reference to FIG. This laser element is a so-called distributed feedback (DFB) laser. 3 is a perspective view showing a part of the laser element in a cutaway state, FIG. 4 is a cross-sectional view taken along the optical axis direction of the laser element, FIG. 5 is a bottom view of the laser element, and FIG. It is sectional drawing along the various directions. In order to clarify the structure of the laser element three-dimensionally, the surface on which the substrate 12 is placed is the xy plane, the normal direction of the surface of the substrate 12 is the z-axis direction, and the optical axis direction of the laser resonator is The structure of this element will be described as the x-axis direction.

  This laser element is formed on a substrate 12 made of n-type InP having a (100) plane as a main surface. Light is generated by injecting current into the InGaAsP active layer 13 from the n-electrode 11 on the back surface of the substrate 12 and the p-electrode 16 on the surface of the substrate 12. The generated light is confined in the z direction by a light confinement structure including a p-type InP clad layer 15 / active layer 13 / substrate 12. Further, the light is confined in the y direction by an optical confinement structure including a semi-insulating InP layer 21 / active layer 13 / semi-insulating InP layer 21. Thus, the light confined in the y direction and the z direction propagates in the x axis direction. A diffraction grating 14 whose refractive index changes periodically is formed in the x-axis direction in which this light propagates. Light is fed back by the diffraction grating 14 to cause laser oscillation.

  The laser light generated in this way is totally reflected by the reflecting mirror 19 formed by etching one end of the waveguide at an angle of 135 ° and guided toward the back surface of the substrate 12. A portion of the back surface of the substrate 12 facing the reflecting mirror 19 is provided with a non-reflective coating 18, and laser light is emitted from the back surface of the substrate 12. Here, the angle of the reflecting mirror 19 is defined by the angle formed between the surface of the semiconductor multilayer structure and the etched inclined surface. Therefore, in the case of the back-emission type horizontal cavity surface emitting laser shown in FIG. 2, in order to emit light just vertically from the back side, it is preferable to set the tilt angle of the reflecting mirror 19 to 135 °. . On the other hand, in the surface emitting type horizontal cavity surface emitting laser shown in FIG. 1, it is preferable that the angle of inclination of the reflecting mirror 17 is 45 ° in order to emit light just vertically from the surface.

  In the horizontal cavity surface emitting laser having the above-described structure, since the cavity is formed in the substrate surface, the cavity length can be increased and high light output can be easily obtained. In addition, since light is emitted in a direction perpendicular to the substrate surface, it is possible to manufacture a laser by a full wafer process and perform characteristic inspection, and manufacturing and inspection costs can be kept low.

As a known example of a conventional horizontal cavity surface emitting laser, a surface emitting type horizontal cavity surface emitting light having a reflective surface etched in a reverse mesa shape formed on the {100} plane of a semiconductor substrate. A laser is disclosed in Patent Document 1. Further, as a second known example, a back-emission type horizontal cavity surface emitting laser having a reflecting mirror formed on a InP substrate and formed by wet etching using a mixed solution of bromine and alcohol is not patented. Reported in Reference 1.
JP 2007-058401 A IEEE Triple Photonics Technology Letters, Vol. 3, No. 9, p. 776

  The conventional horizontal cavity surface emitting laser described above has a problem that it is difficult to emit laser light in a direction just perpendicular to the substrate. This is because, in order to emit laser light in a direction perpendicular to the substrate, the tilt angle of the mirror formed on the substrate must be precisely 45 ° or 135 °, but the mirror tilt angle is 45 with high accuracy. This is because it is difficult to set the angle to 135 °.

  Since there are two etching techniques for mirror formation, dry etching and wet etching, the reason why it is difficult to form an inclined mirror with high angular accuracy in each case will be described.

  First, dry etching is used. In this case, an ion beam etching apparatus such as a chemically assisted ion beam etching (CAIBE) is usually used and tilted at 45 °. An inclined mirror is formed by irradiating an ion beam onto the substrate to be set. However, it is difficult to accurately tilt the holder for holding the substrate with respect to the ion beam irradiation direction by 45 °, and there are cases where the angle of mirror tilt is shifted by several degrees. is there.

  Next, the reason why it is difficult to form an inclined mirror with high angular accuracy when wet etching is used will be described with reference to FIG. FIG. 7 is a schematic diagram showing a processed cross-sectional shape when the (100) plane of the substrate 12 is wet-etched using the insulating film mask 31 and a bromine-based wet etching solution. In order to make it easy to understand the correlation between the processed cross-sectional shape and the atomic arrangement direction, the scale is different from the actual scale, but the state of the atomic arrangement is shown schematically. FIG. 7A shows an atomic arrangement of a cross section cleaved perpendicular to the [011] direction, and FIG. 7B shows an atomic arrangement of a cross section cleaved perpendicular to the [01 bar 1] direction.

  As shown in FIGS. 7A and 7B, when the compound semiconductor substrate is wet-etched, the (111) A surface is often formed naturally, and this surface is used as a reflecting mirror. It is common. However, the angle formed by the (111) A plane and the (100) plane of the surface of the substrate 12 is 54.7 ° in the case of FIG. 7A and 125.3 ° in the case of FIG. 45.0 ° suitable for emitting light perpendicular to the surface direction of the substrate 12, and 9.7 ° shifted from 135.0 ° suitable for emitting light perpendicular to the back surface direction of the substrate 12, respectively. Yes. For this reason, when these surfaces are used as reflecting mirrors, the laser emission light is emitted with a large inclination from the direction perpendicular to the substrate 12.

  However, for example, when light emitted from a semiconductor laser is to be coupled to a fiber or the like, it is preferable that the laser light is emitted from the substrate 12 in an exactly perpendicular direction in order to reduce the coupling loss of the light. Therefore, as described above, the phenomenon in which laser light is emitted from the substrate 12 at an angle is a problem that must be solved.

  The (100) plane or a plane equivalent thereto is the (100) plane, the (010) plane, or the (001) plane. The {100} plane is an expression that collectively represents planes equivalent to these (100) planes. The [011] direction or the equivalent direction is the [011] direction, the [101] direction, or the [110] direction. The <011> direction is an expression that collectively represents the directions equivalent to these [011] directions. In addition, the expression “tilt 9.7 ° in the [011] direction from the (100) plane means that the crystal plane orientation of the substrate surface is not the (100) plane, but only an angle of 9.7 ° from the (100) plane. This indicates that the surface is inclined, and the inclination direction is a direction that becomes the (110) surface when inclined by 90 °.

  A first object of the present invention is to provide a horizontal cavity surface emitting laser that emits laser light from a substrate in an exactly vertical direction and has excellent optical coupling efficiency characteristics.

  A second object of the present invention is to provide an optical module with high optical coupling efficiency.

  A third object of the present invention is to provide an optical transceiver having high optical coupling efficiency.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  (1) The first object of the present invention described above is that an active layer for generating light is laminated on the main surface of the substrate, and an optical waveguide for propagating light on or above the active layer itself is provided on the substrate. The resonator structure is formed in a direction parallel to the main surface and reflects light at least at a part of the optical waveguide, and laser light emitted from the resonator structure is directed toward the surface of the substrate. In a horizontal cavity surface emitting laser in which a reflecting mirror for emission is formed, the substrate is 9.7 ° ± in the [01 bar 1] direction or a direction equivalent thereto from the (100) plane or a plane equivalent thereto. This is achieved by a semiconductor laser characterized by an inclination of 0.5 °.

  Also, the first object of the present invention described above is that an active layer for generating light is laminated on the main surface of the substrate, and an optical waveguide for propagating light on the active layer itself or on the upper part thereof is the main substrate of the substrate. The resonator structure is formed in a direction parallel to the surface, and a light reflecting structure is formed on at least a part of the optical waveguide, and laser light emitted from the resonator structure is emitted toward the back surface of the substrate. In the horizontal cavity surface emitting laser in which the reflecting mirror is formed, the substrate is 9.7 ° ± 0.5 in the [011] direction or the equivalent direction from the (100) plane or the equivalent surface. Achievable by a semiconductor laser characterized by tilting.

  (2) The second object of the present invention is achieved by an optical module having the semiconductor laser having the feature (1) as a component.

  The above second object of the present invention is to provide a submount provided on a can (CAN) stem and at least a first wavelength provided on one surface of the submount and having different use wavelengths. A light-emitting element and a first light-receiving element, a can (CAN) cap or package fixed on the stem and having a hole for light in and out, and a parallel plate shape that is transparent to transmitted light An optical multiplexer / demultiplexer provided with a first wavelength selection filter on one surface of the first substrate and having a mirror on the other surface opposite to the one surface. The above cannula is in a state where the extending direction of the device is inclined by an angle θ (where θ ≠ 2Nπ, N = 0, 1, 2,...) In a two-dimensional cross section with respect to one surface of the optical element mounting substrate. Fixed in cap or package The emitted light from the first light emitting element passes through the first wavelength selective filter and the first substrate and enters the optical fiber outside the cap, and the emitted light from the optical fiber is In the optical module that is incident on the optical multiplexer / demultiplexer, reflected by the first wavelength selection filter, and further reflected by the mirror, then exits the optical multiplexer / demultiplexer and enters the first light receiving element. This is achieved by the first light emitting element being a semiconductor laser having the feature (1).

  The second object of the present invention is to provide a light receiving element having a second light receiving element on the submount in the optical module, and light emitted from the optical fiber has wavelengths λ2 and λ3 (provided that λ2 ≠ λ3) is a wavelength multiplexed light, and the light emitted from the optical fiber is incident on the optical multiplexer / demultiplexer, reflected by the first wavelength selection filter, further reflected by the mirror, and then the wavelength. The light of λ2 passes through the second wavelength selection filter provided on the one surface, exits the optical multiplexer / demultiplexer, and enters the second light receiving element, and the light of wavelength λ3 This is achieved by an optical module that is reflected by a wavelength selection filter, further reflected by the mirror, and then exits the optical multiplexer / demultiplexer and enters the second light receiving element.

  (3) A third object of the present invention is to provide an optical transceiver comprising an optical transmission module and an optical reception module, by mounting the semiconductor laser having the feature (1) on the optical transmission module. Achieved.

  Hereinafter, the operation of the present invention will be described with reference to FIG. FIG. 8 is a schematic diagram showing a processed cross-sectional shape when the tilted substrate 41 made of InP is etched using the insulating film mask 31 and a bromine-based wet etching solution. In order to make it easy to understand the correlation between the processed cross-sectional shape and the atomic arrangement direction, the scale is different from the actual scale, but the state of the atomic arrangement is shown schematically. FIG. 8A shows an atomic arrangement of a cross section obtained by cleaving perpendicularly to the [011] direction in the tilted substrate 41 inclined by 9.7 ° in the [01 bar 1] direction from the (100) plane. ) Shows an atomic arrangement in a cross section of the tilted substrate 41 inclined 9.7 ° in the [011] direction from the (100) plane and cleaved perpendicular to the [01 bar 1] direction.

  A feature of the present invention is that the tilted substrate 41 is used, and the (111) A plane automatically generated by wet etching is accurately inclined by 45 ° or 135 ° with respect to the main surface of the substrate. The object is to realize a horizontal cavity surface emitting laser in which laser light is emitted in a precisely vertical direction. As specific implementation means, the present inventors have found the following two methods.

  First, the first method will be described with reference to FIG. This method is a method of forming a reflecting mirror that is accurately inclined by 45 ° with respect to the surface of the substrate for emitting light from the surface of the substrate. In this method, an inclined substrate 41 tilted by 9.7 ° in the [01 bar 1] direction or an equivalent direction from the (100) plane or an equivalent surface is used as the semiconductor substrate. In other words, an inclined substrate 41 inclined 9.7 ° in the <01 bar 1> direction from the {100} plane is used. As a result, the (111) A plane that is automatically generated by wet etching becomes a plane that is inclined at exactly 45 ° with respect to the main surface of the substrate. Therefore, when the laser light generated in the in-plane direction of the substrate is reflected by the reflecting mirror. The light is emitted in the direction perpendicular to the substrate from the surface side of the substrate.

  Next, the reason why the upper and lower limits of the substrate tilt angle in the first method are set to 9.7 ° ± 0.5 ° will be described. This is a value defined by the optical coupling efficiency between the semiconductor laser and the optical fiber. For example, when the 1.3 micron wavelength band horizontal cavity surface emitting laser of the present invention is applied to a bidirectional optical transceiver module (so-called optical triplexer) using three wavelengths, the optical coupling loss between the semiconductor laser and the optical fiber is reduced. This is because the angle range allowed for the tilt angle of the mirror is specified to be 9.7 ° ± 0.5 ° in order to achieve 3 dB or less.

  Next, the second method will be described with reference to FIG. This method is a method of forming a reflecting mirror inclined by 135 ° with respect to the substrate surface for emitting light from the substrate surface. In this method, an inclined substrate 41 tilted by 9.7 ° in the [011] direction or the equivalent direction from the (100) plane or the equivalent surface is used as the semiconductor substrate. In other words, an inclined substrate 41 inclined 9.7 ° in the <011> direction from the {100} plane is used. As a result, the (111) A plane that is automatically generated by wet etching becomes a plane that is inclined by exactly 135 ° with respect to the main surface of the substrate. Therefore, when the laser beam generated in the in-plane direction of the substrate is reflected by the reflecting mirror. The light is emitted from the back side of the substrate in a direction just perpendicular to the substrate.

  Next, the reason why the upper and lower limits of the substrate tilt angle in the second method are set to 9.7 ° ± 0.5 ° will be described. This is a value defined by the optical coupling efficiency between the semiconductor laser and the optical fiber. For example, when the 1.3 micron wavelength band horizontal cavity surface emitting laser of the present invention is applied to a bidirectional optical transceiver module (so-called optical triplexer) using three wavelengths, the optical coupling loss between the semiconductor laser and the optical fiber is 3 dB. This is because the angle range allowed for the tilt angle of the mirror is defined as 9.7 ° ± 0.5 ° for the following.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  A horizontal cavity surface emitting laser in which laser light is emitted in a direction perpendicular to the substrate can be realized. In addition, the optical coupling efficiency of the optical module or the optical transceiver can be improved.

  Since high-precision adjustment during laser mounting is not required, the mounting process is simplified, and the cost of optical modules and optical transceivers can be greatly reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted. Also, in the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary. Further, in the drawings for explaining the following embodiments, hatching may be given even in a plan view for easy understanding of the configuration.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to an InGaAlAs quantum well type horizontal cavity surface emitting laser element with a wavelength of 1.3 μm band. FIG. 9 is a perspective view showing a part of the laser element in a cutaway state, FIG. 10 is a cross-sectional view taken along the optical axis direction of the laser element, FIG. 11 is a bottom view of the laser element, and FIG. FIG. 13 to FIG. 19 are sectional views showing a method for manufacturing a laser device.

  As shown in FIGS. 9 and 12, the optical waveguide portion of the element is processed in a stripe shape and has a buried hetero type (BH: Buried Hetero) structure. This structure is well known. In this example, the periphery of the stripe-shaped optical waveguide portion in the buried hetero structure is buried with a high-resistance semi-insulating InP layer 21 to which Fe is added.

  The substrate is an n-type InP tilting substrate 41 having a surface tilted by 9.74 ° in the [011] direction from the (100) plane. The active layer 13 has a laminated structure of an optical confinement layer made of n-type InGaAlAs, a strained multiple quantum well layer made of InGaAlAs, and an optical confinement layer made of p-type InGaAlAs. The quantum well layer serving as the active region is designed such that a well layer having a thickness of 7 nm and a barrier layer having a thickness of 8 nm are stacked for five periods to realize sufficient characteristics as a laser. Above these layers, a diffraction grating layer 14 made of an InGaAsP-based material is formed. The structures of the active layer 13 and the diffraction grating layer 14 are formed so that the oscillation wavelength of the DFB laser at room temperature is 1310 nm.

  Here, the light confinement layer provided across the quantum well layer is a layer for enhancing the light confinement of the quantum well layer. The optical waveguide function is generated by sandwiching the core region with a clad layer having a lower refractive index than that, and the optical waveguide function is realized by a laminated structure of a clad layer / quantum well layer / cladding layer. In a specific form, in order to enhance optical confinement in the quantum well layer, an optical confinement layer is provided with the quantum well layer interposed therebetween. For this purpose, the refractive index of the cladding layer is set to a value lower than the refractive index of the optical confinement layer. In the present embodiment, the inclined substrate 41 plays a role in the substrate-side cladding layer. Of course, a substrate-side cladding layer may be separately provided on the inclined substrate 41.

  The polarity of the diffraction grating layer 14 was p-type. Such a structure is called a refractive index coupled DFB laser because only the refractive index periodically changes in the light propagation direction. In this embodiment, the diffraction grating is uniformly formed in the entire region of the DFB laser. However, a so-called phase in which the phase of the diffraction grating is shifted to a part of the region as necessary is described. A shift structure may be provided.

  Next, the manufacturing process of the present embodiment will be described with reference to FIGS. First, as shown in FIG. 13, in order to form the structure of the laser portion, an optical confinement layer made of n-type InGaAlAs, a strained multiple quantum well layer made of InGaAlAs, and p on an inclined substrate 41 made of n-type InP An active layer 13 of InGaAlAs is formed by laminating optical confinement layers made of type InGaAlAs. Next, a multilayer structure including a diffraction grating layer 14 made of InGaAsP is formed on the active layer 13. Further, a cladding layer 15 made of p-type InP and a contact layer 61 made of p-type InGaAs are formed thereon.

  Next, as shown in FIG. 14, a silicon dioxide film 62 is formed on the inclined substrate 41 having the multilayer structure as described above. Then, by using this silicon dioxide film 62 as a mask, the contact layer 61, the p-type cladding layer 15, the diffraction grating layer 14, the active layer 13, and part of the tilted substrate 41 are dry etched to form an optical waveguide. To do. For this etching, a reactive ion etching method using chlorine gas is used.

  Next, the tilted substrate 41 is carried into a crystal growth furnace, and as shown in FIG. 15, the semi-insulating InP layer 21 is embedded at 600 ° C. using a MOVPE (Metal Organic Vapor Phase Epitaxy) method. Growing forms a buried heterostructure. The buried heterostructure is a structure in which both sides of the light traveling direction of the optical waveguide are buried with a material capable of confining light. In this example, high resistance semi-insulating InP21 doped with Fe is used as a material used for confinement. FIG. 12 is a cross-sectional view of the laser element along a plane intersecting the light traveling direction. The embedded structure will be fully understood from this figure. In the step of forming the buried structure, both sides of the light guide in the light traveling direction are buried, and at the same time, a semi-insulating InP21 layer is buried at the light emitting side end of the light guide.

  Next, after removing the silicon dioxide film 62 used as a mask for etching and selective growth, as shown in FIG. 16, a silicon nitride film 63 for an etching mask is formed, and the semi-insulating InP layer 21 is formed at 135 °. Wet etching at an inclination angle. For this etching, a wet etching solution in which bromine and methanol are mixed is used. Due to the effect that the (111) A plane formed by this wet etching is inclined at an angle of just 135 ° with respect to the substrate surface, a 135 ° reflecting mirror 19 suitable for vertical emission from the back surface of the substrate is realized. As the wet etching solution for forming the 135 ° reflecting mirror 19, other than the above wet etching solution in which bromine and methanol are mixed, for example, a hydrobromic acid wet etching solution or the like can be used.

  Next, after removing the silicon nitride film 63, as shown in FIG. 17, a p-electrode 16 is deposited on the contact layer 61, and unnecessary portions of the p-electrode 16 are dry-etched, whereby a reflecting mirror on the end face is formed. Form.

  Next, the back surface of the inclined substrate 41 is polished to reduce its thickness to about 100 μm. Subsequently, as shown in FIG. 18, the lens 51 is formed by performing wet etching using a bromine-based solution using the silicon nitride film 64 formed on the back surface of the tilted substrate 41 as a mask.

  Next, after removing the silicon nitride film 64, as shown in FIG. 19, the antireflection coating film 18 made of silicon nitride oxide is formed on the surface of the lens 51, and then the n-electrode 11 is formed on the back surface of the tilted substrate 41. Form. Although not shown in the drawing, a high reflection coat used in a normal semiconductor optical device is applied to the rear end face of the device.

  The horizontal cavity surface emitting laser of the present embodiment has an average value of slope efficiency of 0.4 W / A at room temperature and continuous conditions, and exhibits high-efficiency oscillation characteristics. The laser light was emitted just vertically from the back surface of the substrate, and the deviation from the direction perpendicular to the substrate was 1 ° or less. On the other hand, in order to show the effect of the present invention, in the comparative laser element manufactured using the InP substrate having the (100) plane as the main surface, the laser emission light is tilted by 20 ° from the direction perpendicular to the substrate. The effect of the present invention was confirmed.

  As a result, it has been found that due to the effect of the present invention, the laser beam of the horizontal cavity surface emitting laser is emitted in a direction perpendicular to the substrate. In addition, as a result of conducting a constant light output energization test at 50 ° C. and 5 mW for the laser element of the present invention, an estimated lifetime of 1 million hours was obtained, and it was also demonstrated that the laser element of the present invention has high reliability. It was done.

  In this embodiment, an example in which the present invention is applied to an InGaAlAs quantum well type laser having a wavelength band of 1.3 μm formed on an InP tilt substrate has been described. However, the substrate material, the active layer material, and the oscillation wavelength are It is not limited to the example shown in the present embodiment. The present invention is similarly applicable to laser elements composed of other material systems such as a 1.55 μm band InGaAsP laser.

(Embodiment 2)
This embodiment is applied to an InGaAsP quantum well type horizontal cavity surface emitting laser with a wavelength of 1.3 μm.

  FIG. 20 is a cross-sectional view of the laser device of the present embodiment. The laser element of the present embodiment is formed on an inclined substrate 71 made of n-type InP that is inclined by 9.7 ° in the [01 bar 1] direction from the (100) plane. The active layer 13 has a stacked structure of an optical confinement layer made of n-type InGaAsP, a multiple quantum well layer made of InGaAsP, and an optical confinement layer made of p-type InGaAsP. A diffraction grating layer 14 made of InGaAsP is formed on the active layer 13. The active layer 13 and the diffraction grating layer 14 are formed so that the oscillation wavelength of the DFB laser at room temperature is 1310 nm.

  The polarity of the diffraction grating layer 14 is p-type. Such a structure is called a refractive index coupled DFB laser because only the refractive index periodically changes in the light propagation direction. In this embodiment, the diffraction grating is uniformly formed in the entire region of the DFB laser. However, if necessary, a so-called phase in which the phase of the diffraction grating is shifted in part of the region is described. A shift structure may be provided.

  In order to manufacture the laser device, first, as shown in FIG. 21, an active layer 13 composed of a light confinement layer, a multiple quantum well layer, and a light confinement layer is formed on a tilted substrate 71. Subsequently, the active layer 13 After forming a multilayer structure including the diffraction grating layer 14 made of InGaAsP on the upper part of the first layer, a cladding layer 15 made of p-type InP and a contact layer 61 made of p-type InGaAs are formed on the upper part of the diffraction grating layer 14.

  Next, a buried heterostructure optical waveguide is formed using the same technique as described in the first embodiment. However, this embodiment differs in that an embedded structure is formed only in a direction perpendicular to the light propagation direction of the optical waveguide and no embedded structure is formed at the light emitting side tip of the optical waveguide. I want.

  Next, as shown in FIG. 22, a silicon dioxide film 62 is formed on the multilayer structure. Then, by using this silicon dioxide film 62 as a mask, the contact layer 61, the cladding layer 15, the diffraction grating layer 14, the active layer 13, and a part of the tilted substrate 71 are wet-etched, thereby reflecting the mirror 17 tilted at 45 °. Form. For this wet etching, a mixed solution of hydrobromic acid and hydrogen peroxide is used. By this wet etching, the (111) A plane is inclined at an angle of just 45 ° with respect to the substrate surface, so that the angle of 45 ° is suitable for emitting laser light in a direction just perpendicular to the upper surface of the inclined substrate 71. It is possible to form the reflecting mirror 17 tilted in the direction.

  Next, after removing the silicon dioxide film 62, as shown in FIG. 23, a p-electrode 16 is formed on the contact layer 61 by vapor deposition, and unnecessary portions of the p-electrode 16 are dry-etched, thereby reflecting the reflection mirror at the end face. Form. Next, after polishing the back surface of the tilt substrate 71 to reduce its thickness to about 90 μm, the n-electrode 11 is formed on the back surface of the tilt substrate 71 as shown in FIG. Although not shown in the drawing, a high reflection coat used in a normal semiconductor optical device is applied to the rear end face of the device.

  The 1.3 μm band horizontal cavity surface emitting laser of the present embodiment has an average value of the slope efficiency of 0.35 W / A at room temperature and continuous conditions, and exhibits high-efficiency oscillation characteristics. In addition, a laser beam that exits from the surface of the laser element just vertically was obtained reflecting the effect of the present invention. The deviation of the laser beam emission direction from the direction perpendicular to the substrate surface was 0.5 degrees or less. On the other hand, in order to show the effect of the present invention, in a comparative 1.3 μm band horizontal cavity surface emitting laser having a (100) plane having a reflecting mirror formed by dry etching as a main surface, the tilt angle of the reflecting mirror is Since it is 46 ° with respect to the substrate surface and shifted by 1 ° from 45 ° suitable for vertical emission, a vertical emission beam cannot be obtained, and the emission direction is 7 ° from the direction perpendicular to the substrate. became.

  As a result, a surface emitting type horizontal cavity surface emitting laser that emits light in a direction perpendicular to the substrate was obtained by the effect of the present invention. Moreover, as a result of conducting a constant light output energization test at 80 ° C. and 3 mW for the laser element of the present invention, an estimated lifetime of 2 million hours was obtained, and it was also demonstrated that the laser element of the present invention has high reliability. It was done. In this embodiment, an example in which InP is used as a semiconductor substrate has been described. However, the present invention has the same effect even when another III-V group semiconductor substrate such as a GaAs substrate is used.

  FIG. 24 shows a structure of an optical transmission module in which the laser element 81 of the present embodiment is mounted on a heat sink 82, and then the optical lens 83, the rear end face light output monitoring photodiode 84, and the optical fiber 85 are integrated. FIG. The threshold current was 5 mA and the oscillation efficiency was 0.3 W / A under continuous conditions at room temperature. Further, reflecting the effect of the present invention in which the laser beam is emitted in the vertical direction, the optical coupling efficiency with the lens is high, and the maximum module light output of 5 mW or more is achieved. Reflecting the effects of the present invention, the mounting is easy and the optical transmission module can be manufactured at low cost.

  FIG. 25 is a diagram showing a structure of a can module in which the laser element 81 of the present embodiment is incorporated into a can (CAN) type package 91. As shown in FIG. A package 91 produced by die press molding was used as the can module housing. Reflecting the effect of the present invention in which the semiconductor laser emits light in a direction just perpendicular to the substrate, a can module could be fabricated with easy mounting.

(Embodiment 3)
In the present embodiment, the semiconductor laser of the present invention is applied to an optical module used as a terminal for wavelength division multiplexing or single-core bidirectional optical transmission in which light of a plurality of wavelengths is transmitted through a single optical fiber. is there.

  FIG. 26 is a cross-sectional view of this optical module, and is an example in which the present invention is applied to a so-called optical triplexer module of a bidirectional optical transceiver module using three wavelengths. FIG. 27 is a diagram for explaining a part of the structure of the optical module in detail.

  As shown in FIG. 26, in the optical module of the present embodiment, an optical element mounting substrate 101 in which a light emitting element 111 and light receiving elements 112 and 113 are mounted on a submount 110 is mounted on a can stem 114. The correlator 102 is mounted on the can cap 103 to constitute a triplexer module 115. The operating wavelengths of the optical elements 111, 112, and 113 are λ1, λ2, and λ3, respectively, and the wavelength relationship is λ1 <λ2 <λ3. However, the magnitude relationship between the wavelengths is not limited to this. In FIG. 26, the optical elements are arranged from the shortest wavelength to the longest wavelength used.

  The can cap 103 is provided with irregularities for enabling mounting of the optical multiplexer / demultiplexer. However, it is sufficient if the optical multiplexer / demultiplexer can be fixed inside the can cap 103. The fixing means is not limited. Therefore, it is not essential to provide unevenness. For example, the package member may be provided with a cut so that the optical multiplexer / demultiplexer and the package member can be fitted. Moreover, the package member may be provided with both unevenness and notches.

  The optical multiplexer / demultiplexer 102 has a transparent glass substrate 105 as a supporting substrate, and a first wavelength selection filter 106 and a second wavelength selection filter 107 are mounted adjacent to each other on one surface, and are opposed surfaces parallel to this surface. In addition, a first mirror 108 and a second mirror 109 are mounted. The optical multiplexer / demultiplexer 102 is mounted by aligning the outer shape of the can cap 103 with the concavo-convex shape and bonded with a UV curable resin. The material of the transparent glass substrate 105 is BK7, and the thickness is 1136 μm.

The transparent glass substrate 105 is mounted so that the angle with respect to the plane is 20 °, and the projection onto the plane of the dimension z shown in FIG. 27, that is, the pitch of the multiple reflection, is 500 μm. The wavelength selection filters 106 and 107 are composed of a dielectric multilayer film made of Ta ₂ O ₅ (ditantalum pentoxide) and SiO ₂ (silicon dioxide). The first wavelength selection filter 106 has a separation wavelength λ _th that satisfies λ ₁ <λ _th <λ _2, a filter that transmits light having a shorter wavelength than λ _th and reflects light having a longer wavelength (so-called so-called filter) Short pass filter). The second filter 107 is a short-pass filter with a separation wavelength of λ ₂ <λ _th <λ ₃ . The first mirror 108 is the same as the first wavelength selection filter 106, and the second mirror 109 is the same as the second wavelength selection filter 107.

  The light emitting element 111 on the optical element integrated substrate is composed of the horizontal cavity surface emitting laser of the present invention. An edge-emitting laser can be used for the light-emitting element 111, but a vertical-emission type is desirable for ease of mounting, and a lens-integrated type is desirable from the viewpoint of ease of optical coupling and reduction of the number of components. In the present embodiment, it is possible to easily obtain high optical coupling, reflecting the effect of the present invention in which light is emitted from the substrate in an exactly vertical direction. For the same reason, the light receiving elements 112 and 113 are also preferably surface incident types. An amplifier and a capacitor are also mounted inside the can cap 103, but they are not shown because they are the same as ordinary optical modules.

  The material of the transparent glass substrate 105 is not particularly limited as long as it is transparent with respect to the wavelength to be used. However, a material that is inexpensive and has high processing accuracy is desirable. In order to satisfy this condition, BK7 is used in this embodiment, but other glass materials, dielectric materials, or semiconductor materials may be used.

Next, the operation of the optical module of the present embodiment will be described. The light having the wavelength λ ₁ emitted from the light emitting element 111 reaches the first wavelength selection filter 106. The first wavelength selection filter 106 transmits light having the wavelength λ ₁ , then refracts by the transparent glass substrate 105, translates the optical path, and is optically connected to an external optical fiber via the package lens 104. On the other hand, the light combined with the wavelengths λ ₂ and λ ₃ emitted from the optical fiber is incident on the transparent glass substrate 105, is refracted, and reaches the first wavelength selection filter 106. Light of wavelengths λ ₂ and λ ₃ is reflected and reaches the first mirror 108 facing it. Since the first mirror 108 is the same as the first wavelength selection filter 106, the light of the wavelengths λ ₂ and λ ₃ is reflected again. Here, the reason why the mirror 108 is the same as that of the filter 106 is to improve the stopping power with respect to the light having the wavelength λ ₁ . The light having the wavelength λ ₁ emitted from the light emitting element 111 is slightly reflected on the surface of the package lens 104, the fiber end face, and other places, and is incident again as return light. Even this wavelength lambda ₁ of the return light is a slight amount of light, the noise made incident on the light receiving elements 112 and 113. The return light of wavelength λ ₁ is transmitted through the filter 106, but a small amount is reflected. Therefore, the light is transmitted again by the mirror 108 to further reduce the amount of light.

  For the reasons described above, in this embodiment, the mirror 108 is the same as the filter 106. However, if the wavelength separation specification is not strict, a normal mirror having no wavelength dependency may be used. It is enough.

  The light reflected by the mirror 108 enters the filter surface again. In the simplest design, the light reflected once by the mirror 108 is incident on the second wavelength selection filter 107, but in this configuration, the reflected light from the mirror 108 is again on the first wavelength selection filter 106. And is made to reciprocate between the wavelength selective filter 106 and the mirror 108. This is because the interval between the light emitting element 111 and the light receiving element 112 is made larger than the projection of the multiple reflection pitch. This is because a light emitting element driven at high speed may become a noise source (referred to as electrical crosstalk) for the light receiving element side. When there is no electrical crosstalk or any other special reason, it is desirable that the number of reflections be minimized by making the multiple reflection pitch in the transparent glass substrate 105 coincide with the device mounting pitch.

The light that has made two round trips between the first wavelength selection filter 106 and the mirror 108 enters the second wavelength selection filter 107. Here, the light of wavelength λ _{2 and} the light of wavelength λ ₃ are separated, pass through the wavelength λ ₂ filter, undergo refraction, and enter the light receiving element 112 perpendicularly. On the other hand, the light having the wavelength λ ₃ is reflected and enters the mirror 109. For the mirror 109, the same dielectric multilayer filter as the wavelength selection filter 107 is used for the same reason as in the case of the mirror 108. The light reflected by the mirror 109 passes through an interface without a filter (however, with a non-reflective coating) and enters the light receiving element 113.

  This embodiment reflects the effect of the laser element of the present invention that the laser beam emitted from the laser element is emitted in the direction perpendicular to the substrate, and has a large tolerance for optical axis adjustment when the laser element is mounted. The mounting process becomes extremely easy, and the optical module can be manufactured at a low cost.

(Embodiment 4)
This embodiment is applied to the optical transceiver using the optical transmission module of the present invention described in the second embodiment.

  As shown in FIG. 28, the optical transceiver of this embodiment includes an optical transceiver housing 121, electrical input / output pins 122, an optical fiber 123, an optical connector 124, an optical reception module 125, an optical transmission module 126, and signal processing control. Part 127. This optical transceiver has a function of converting a received optical signal into an electrical signal and outputting the electrical signal to the outside via the electrical input / output pin 122, and optically inputs an electrical signal input from the outside via the electrical input / output pin 122. It has a function of converting to a signal and transmitting it.

  The optical fiber 123 is connected to the optical transceiver housing 121 at one end and is connected to the optical connector 124 at the other end. The optical connector 124 has a structure capable of transmitting the received light input from the external optical transmission path to the optical fiber 123 and has a structure capable of transmitting the transmission light input from the optical fiber 123 to the external optical transmission path.

  According to the present embodiment, an optical transceiver can be manufactured at a very low mounting cost, reflecting the effect of mounting the semiconductor laser of the present invention having high optical coupling efficiency.

(Embodiment 5)
This embodiment is applied to a GaInAs / AlGaInP semiconductor laser having a wavelength of 980 nm. FIG. 29 is an explanatory view showing a problem to be solved in the present embodiment, FIGS. 30 and 31 are perspective views showing a laser element of the present embodiment, and FIG. 32 is a cross section taken along line AA in FIG. FIG. 33 and FIG. 33 are cross-sectional views along the line BB in FIG.

  In this embodiment mode, an example in which an etching solution having a significantly different etching rate depending on a crystal composition is described. In the GaInAs / AlGaInP system, when a hydrochloric acid-based etchant is used as the mirror-forming etchant, the crystal composition of the clad layers 131 and 133 and the active layer 132 is greatly different, so that the active layer is exposed to the 135 ° mirror surface. In this case, due to the difference in the etching rate due to the chemical etching, as shown in FIG.

  29, reference numeral 131 denotes a cladding layer made of n-type AlGaInP, 132 denotes a multi-quantum well active layer made of GaInAs / GaInP, 133 denotes a cladding layer made of p-type AlGaInP, and 134 denotes a p-type GaAs layer.

  As a method for preventing the unevenness of the mirror surface as described above, in this embodiment, a band-shaped raised region 136 as shown in FIGS. 30 and 31 is provided in advance on a substrate on which crystal growth is performed, and the mirror surface is formed in such a manner. By forming it on the raised portion, a mirror surface without unevenness is formed.

In the present embodiment, first, an n-type GaAs substrate 135 cut out in a substrate surface orientation inclined 9.7 degrees in the [011] direction from the (100) plane has a width of 50 μm and a height as shown in FIG. A 1 μm band-like raised region 136 is formed. Then, a Bragg reflector 137 having a quarter-wavelength optical length that is lattice-matched to GaAs is formed on the raised region 136 by crystal growth. The Bragg reflector 137 is composed of a ten-period film of n-type Ga _0.01 Al _{0.99 As} 138 and n-type GaAs 139, and its reflectivity is 60%. Next, after such a Bragg reflector 137 is formed, crystal growth is continued to form a semiconductor laser multilayer crystal 140 lattice-matched to GaAs.

A specific structure of the multilayer crystal portion of the semiconductor laser will be described with reference to FIGS. This structure consists of _{(Al 0.5 Ga 0.5) 0.5 In} 0.5 second 1n cladding layer 141 made of P (Si-doped ^{= 7x10} 17 ^{cm -3,} thickness _{= 1μm), (Al 0.45 Ga} 0.65) 0.5 In 0.5 P ridges Part guide layer 142 (Si-doped = 7 × 10 ¹⁷ cm ⁻³ , thickness = 0.2 μm), (Al _0.5 Ga _0.5 ) _0.5 n _0.5 P second n cladding layer 143 (Si-doped = 7 × 10 ¹⁷ cm ⁻³ , thickness 1 μm), strained quantum well active layer 144 made of GaInP / GaInAs, first p-clad layer 145 made of p-type (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P (Mg doping = 7 × 10 ¹⁷ cm ⁻³ , thickness = 2 μm) ), p-type _{(Al 0.5 Ga 0.5) 0.5 In} 0.5 P / p -type Ga _0.5 an In _0.5 consists P superlattice etching stop layer _{146, (Al 0.5 Ga 0.5)} 0.5 In the second consisting of _0.5 P Cladding layer 147 (Mg-doped ^{= 7x10} 17 ^{cm -3,} thickness = 2 [mu] m), and p-type contact layer 148 made of GaAs (Zn-doped ^{= 7x10} 18 ^{cm -3,} thickness = 0.5 [mu] m) MOVPE method each layer Are sequentially formed by crystal growth using

  Next, a 135 ° tilt mirror 149 is formed on the belt-like raised region 136 by etching using the insulating film as a mask. Specifically, first, the epitaxial growth layer other than the region protected by the insulating film (mask) is etched to the GaInAs / GaInP active layer 144 with a bromic acid-based etchant. Next, the second n-type cladding layer 143 to the first n-type cladding layer 141 are chemically etched with a hydrochloric acid-based etchant. Since the etching rate of the hydrochloric acid-based etching solution varies greatly depending on the crystal plane, the (111) A plane is formed with good reproducibility. Since the substrate surface is tilted by about 10 degrees from the (100) plane, the (111) A plane whose angle to the (100) plane is about 55 ° is formed at an angle of 135 ° with respect to the substrate surface. The structure is the same as that described in the first embodiment. There is a difference in Al composition of 10% between the first and second n-clad layers and the raised guide layer, but the difference in etching characteristics is small in the same material system, and etching can be obtained almost flatly. there were.

  Next, an etching mask is formed again by photolithography, and a second inclined surface 150 that forms an angle of 45 ° with respect to the substrate surface is formed using an ion beam etching technique. This etching was performed so that the plasma was incident in a direction inclined by 45 ° from the direction perpendicular to the substrate. As a result, a first inclined surface 149 that forms an angle of 135 ° with respect to the substrate surface and a second inclined surface 150 that forms an angle of 45 ° are formed.

Next, a ridge shape 151 having a width of 2 μm is formed by etching using an insulating film or the like as a mask. Etching at this time does not matter, and various methods such as wet etching, RIE (Reactive Ion Beam Etching), RIBE (Reactive Ion Beam Etching), and ion milling can be used. This etching is stopped in the middle of the clad layer 145 made of p-type (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P so as not to reach the strained quantum well active layer 144.

  Next, the substrate surface in such a state is covered with a silicon dioxide film, and the silicon dioxide film is removed only on the upper surface of the ridge shape 151 to form a contact hole 153. Subsequently, a p-side ohmic electrode 154 is formed on the upper surface of the contact layer 148, and an n-side ohmic electrode is formed on the back surface of the GaAs substrate (not shown). An insulating high reflection film 156 (reflectance 98%) made of an eight-layer film of silicon dioxide and silicon nitride is provided on the substrate surface facing the second inclined surface 150. The elements are separated by dicing to obtain a semiconductor laser element having a resonator length of about 400 μm. Thereafter, bonding is performed on an AlN heat sink with the first main surface facing down.

  In the semiconductor laser of the present embodiment, light emission occurs in the strained quantum well active layer 144 when a voltage is applied between the p electrode and the n electrode. The emitted beam is reflected by the 135 ° mirror 149 and the 45 ° mirror 150, and resonates between the Bragg reflector 137 and the insulator high reflection film 156 to become laser light. Since the Bragg reflector 137 has a lower reflectance than the high dielectric insulator 156, a part of the laser light passes through the Bragg reflector 137 and is emitted through the GaAs substrate. In the raised region 136, the active layer 144 is changed to guide the light, and the raised guide layer 142 guides light. In this region, the optical waveguide function is not lost, and good optical coupling with the 135 ° mirror 149 and the Bragg reflector 137 is maintained. Be drunk.

  The prototype semiconductor laser oscillated continuously at room temperature with a threshold current of about 10 mA, had an oscillation wavelength of about 980 nm, and stably oscillated in a transverse single mode up to a maximum optical output of 300 mW. Further, even when the light output was increased, the end face did not deteriorate, and the maximum light output of 300 mW was limited by thermal saturation. Further, when 30 semiconductor lasers were continuously driven with the light output constant at 100 mW under the condition of the environmental temperature of 80 ° C., all elements operated stably for 10,000 hours or more without deterioration of the end faces.

  In the present embodiment, the structure has been described by taking a GaInAs / GaInP-based material as an example. However, the same structure is used in other material systems in which the active layer composition is significantly different from the cladding layer composition, such as the AlGaInP / GaInP diameter. Needless to say, it is also effective.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention can be applied to semiconductor laser elements such as lasers for optical communication and lasers for optical disks, optical modules such as optical transmission modules and can modules equipped with the semiconductor laser elements, and optical transceivers.

It is sectional drawing which shows the conventional horizontal resonator surface emitting laser in which light radiate | emits from the surface of a semiconductor substrate. It is sectional drawing which shows the conventional horizontal resonator surface emitting laser in which light radiate | emits from the back surface of a semiconductor substrate. FIG. 3 is a perspective view showing a part of the horizontal cavity surface emitting laser shown in FIG. It is sectional drawing along the optical axis direction of the horizontal resonator surface emitting laser shown in FIG. FIG. 3 is a bottom view of the horizontal cavity surface emitting laser shown in FIG. 2. FIG. 3 is a cross-sectional view along a direction perpendicular to the optical axis of the horizontal cavity surface emitting laser shown in FIG. 2. 2A and 2B are diagrams for explaining a problem to be solved by the present invention, in which FIG. 1A shows an atomic arrangement of a cross section cleaved perpendicular to the [011] direction, and FIG. 2B shows a cleavage perpendicular to the [01 bar 1] direction. Shows the atomic arrangement of the cross section. It is a figure explaining the effect | action of this invention, (a) is atomic arrangement | positioning of the cross section cut | disconnected perpendicularly to the [011] direction in the inclination board | substrate inclined 9.7 degrees to the [01 bar 1] direction from the (100) plane. (B) shows the atomic arrangement of a cross section that is cleaved perpendicularly to the [01 bar 1] direction in an inclined substrate inclined 9.7 ° in the [011] direction from the (100) plane. It is a perspective view which fractures | ruptures and shows a part of laser device which is Embodiment 1 of this invention. It is sectional drawing along the optical axis direction of the laser element which is Embodiment 1 of this invention. It is a bottom view of the laser element which is Embodiment 1 of this invention. It is sectional drawing along the direction perpendicular | vertical to the optical axis of the laser element which is Embodiment 1 of this invention. It is sectional drawing which shows the manufacturing method of the laser element which is Embodiment 1 of this invention. It is sectional drawing which shows the manufacturing method of the laser element following FIG. It is sectional drawing which shows the manufacturing method of the laser element following FIG. FIG. 16 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 15. FIG. 17 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 16. FIG. 18 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 17. FIG. 19 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 18. It is laser element sectional drawing which is Embodiment 2 of this invention. It is sectional drawing which shows the manufacturing method of the laser element which is Embodiment 2 of this invention. FIG. 22 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 21. FIG. 23 is a cross-sectional view showing a method for manufacturing the laser element following FIG. 22. It is a figure which shows the structure of the optical transmission module which mounts the laser element which is Embodiment 2 of this invention. It is a figure which shows the structure of the can module which mounts the laser element which is Embodiment 2 of this invention. It is sectional drawing of the optical module carrying the laser element which is Embodiment 3 of this invention. FIG. 27 is an essential part enlarged cross-sectional view illustrating the operation of the optical module shown in FIG. 26. It is a figure which shows the structure of the optical transceiver carrying the optical module shown in FIG. It is a figure explaining the subject which Embodiment 5 of this invention tends to solve. It is a perspective view which shows the laser element which is Embodiment 5 of this invention. It is a perspective view which shows the laser element which is Embodiment 5 of this invention. FIG. 32 is a cross-sectional view taken along line A-A ′ of FIG. 31. FIG. 32 is a cross-sectional view taken along line B-B ′ of FIG. 31.

Explanation of symbols

11 n-electrode 12 (100) plane InP substrate 13 active layer 14 diffraction grating 15 p-type InP clad layer 16 p-electrode 17 front-surface reflecting mirror 18 non-reflective coating 19 back-surface emitting mirror 21 semi-insulating InP layer 31 insulating film Mask 41 Tilt substrate 51 Lens 52 Emission light 61 Contact layer 62 Silicon dioxide film 63 Silicon nitride film 64 Silicon nitride mask 71 Tilt substrate 81 Laser element 82 Heat sink 83 Optical lens 84 Photo diode 85 Optical fiber 91 Can type package 101 Optical element mounting substrate 102 Optical multiplexer / demultiplexer 103 Can cap 104 Package lens 105 Transparent substrate 106 Wavelength selection filter 107 Wavelength selection filter 108 Mirror 109 Mirror 110 Submount 111 Light emitting element 112 Light receiving element 113 Light receiving element 114 Can stem 15 Triplexer Module 121 Optical Transceiver Case 122 Electrical Input / Output Pin 123 Optical Fiber 124 Optical Connector 125 Optical Receiver Module 126 Optical Transmitter Module 127 Signal Processing Control Unit 131 n-type AlGaInP Clad Layer 132 GaInAs / GaInP Multiple Quantum Well Active Layer 133 p Type AlGaInP cladding layer 134 p-type GaAs layer 135 GaAs tilted substrate 136 band-like raised region 137 Bragg reflector 138 n-type Ga0.01Al0.99As
139 n-type GaAs
140 Semiconductor laser multilayer crystal 141 First n clad layer 142 Guide layer 143 Second n clad layer 144 GaInP / GaInAs strained quantum well active layer 145 First p clad layer 146 Superlattice etching stop layer 147 Second p clad layer 148 p-type GaAs contact layer 149 135 ° mirror surface 150 inclined surface 151 ridge shape 152 silicon dioxide film 153 contact hole 154 p-side ohmic electrode 156 insulator high reflection film

Claims (10)

An active layer that generates light is stacked on the main surface of the semiconductor substrate,
An optical waveguide for propagating light is formed in the active layer or an upper portion thereof in a direction parallel to the main surface of the semiconductor substrate,
A resonator that reflects light is formed at least at an end of the optical waveguide,
A horizontal cavity surface emitting semiconductor laser element in which a reflecting mirror for emitting laser light emitted from the resonator toward the surface of the semiconductor substrate is formed,
The semiconductor laser device, wherein the semiconductor substrate is inclined 9.7 ° ± 0.5 ° in the [01 bar 1] direction or an equivalent direction from the (100) plane or an equivalent surface thereof. An active layer that generates light is stacked on the main surface of the semiconductor substrate,
An optical waveguide for propagating light is formed in the active layer or an upper portion thereof in a direction parallel to the main surface of the semiconductor substrate,
A resonator that reflects light is formed at least at an end of the optical waveguide,
A horizontal cavity surface emitting semiconductor laser element in which a reflecting mirror for emitting laser light emitted from the resonator toward the back surface of the semiconductor substrate is formed,
The semiconductor laser device, wherein the semiconductor substrate is inclined from the (100) plane or a plane equivalent thereto by 9.7 ° ± 0.5 ° in the [011] direction or a direction equivalent thereto.   3. The semiconductor laser device according to claim 1, wherein the semiconductor substrate is made of InP. An active layer that generates light is stacked on the main surface of the semiconductor substrate,
An optical waveguide for propagating light is formed in the active layer or an upper portion thereof in a direction parallel to the main surface of the semiconductor substrate,
A resonator that reflects light is formed at least at an end of the optical waveguide,
An optical module including a horizontal resonator surface type light emitting laser element on which a reflecting mirror for emitting laser light emitted from the resonator in the front or back direction of the semiconductor substrate is formed,
The semiconductor substrate is inclined 9.7 ° ± 0.5 ° from the (100) plane or a plane equivalent to the [01 bar 1] direction or a direction equivalent thereto, or the [011] direction or a direction equivalent thereto. An optical module characterized in that   The optical module according to claim 4, wherein the semiconductor substrate is made of InP. A submount provided on the can stem;
At least a first light-emitting element and a first light-receiving element provided on one surface of the submount and having different use wavelengths from each other;
A can cap or package fixed on the stem and having a hole for light in and out at the top thereof;
A first wavelength selection filter provided on the first surface of the first substrate having a parallel plate shape and having transparency to the passing light;
An optical multiplexer / demultiplexer provided with a mirror on the other surface facing the first surface;
Have
The extending direction of the optical multiplexer / demultiplexer is tilted by an angle θ (θ ≠ 2Nπ, where N = 0, 1, 2,...) In a two-dimensional section with respect to one surface of the optical element mounting substrate. Fixed in the can cap or in the package,
The outgoing light from the first light emitting element passes through the first wavelength selective filter and the first substrate, and enters the optical fiber outside the can cap or the package,
The outgoing light from the optical fiber is incident on the optical multiplexer / demultiplexer, reflected by the first wavelength selection filter, further reflected by the mirror, and then emitted from the optical multiplexer / demultiplexer. An optical module incident on a light receiving element,
The first light emitting element is:
An active layer that generates light is stacked on the main surface of the semiconductor substrate,
An optical waveguide for propagating light is formed in the active layer or an upper portion thereof in a direction parallel to the main surface of the semiconductor substrate,
A resonator that reflects light is formed at least at an end of the optical waveguide,
A horizontal cavity surface emitting semiconductor laser element in which a reflecting mirror for emitting laser light emitted from the resonator in the front or back direction of the semiconductor substrate is formed;
The semiconductor substrate is inclined by 9.7 ° ± 0.5 ° from the (100) plane or a plane equivalent thereto in the [01 bar 1] direction or equivalent, or in the [011] direction or equivalent direction. An optical module characterized by that.   The optical module according to claim 6, wherein the semiconductor substrate is made of InP. A second light receiving element on the submount;
The outgoing light from the optical fiber is wavelength multiplexed light having light of wavelengths λ2 and λ3 (where λ2 ≠ λ3),
Light emitted from the optical fiber is incident on the optical multiplexer / demultiplexer, reflected by the first wavelength selection filter, further reflected by the mirror, and then provided with light having the wavelength λ2 on the first surface. And passes through the second wavelength selection filter, exits the optical multiplexer / demultiplexer, enters the second light receiving element, the light of the wavelength λ3 is reflected by the second wavelength selection filter, and The optical module according to claim 6, wherein the optical module is emitted from the optical multiplexer / demultiplexer and incident on the second light receiving element after being reflected by a mirror. An optical transceiver comprising an optical transmission module and a reception module, wherein a semiconductor laser element is mounted on the optical transmission module,
The semiconductor laser element is
An active layer that generates light is stacked on the main surface of the semiconductor substrate,
An optical waveguide for propagating light is formed in the active layer or an upper portion thereof in a direction parallel to the main surface of the semiconductor substrate,
A resonator that reflects light is formed at least at an end of the optical waveguide,
A horizontal cavity surface emitting semiconductor laser element in which a reflecting mirror for emitting laser light emitted from the resonator in the front or back direction of the semiconductor substrate is formed;
The semiconductor substrate is inclined 9.7 ° ± 0.5 ° from the (100) plane or a plane equivalent to the [01 bar 1] direction or a direction equivalent thereto, or the [011] direction or a direction equivalent thereto. An optical transceiver.   The optical transceiver according to claim 9, wherein the semiconductor substrate is made of InP.

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