JP2003037328A - Optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor device wherein decrease in reliability of an optical semiconductor device which is caused by heat generation of a light emitting element can be restrained. SOLUTION: The optical semiconductor device is provided with a submount and the light emitting element mounted on the submount. Material constituting the submount has thermal conductivity higher than or equal to 150 W/mK, and a thermal expansion coefficient of 0.5-1.5 when a thermal expansion coefficient of material constituting the light emitting element is set as 1.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device represented by a semiconductor laser device.

[0002]

2. Description of the Related Art For example, a light emitting element such as a semiconductor laser is
Practical application is progressing in the fields of optical information processing and optical communication, and element reliability is an extremely important factor in any field. Therefore, in order to avoid deterioration of the element function due to the heat generation amount of the semiconductor laser, it is general to use a metal radiator as a heat sink. However, the difference in coefficient of thermal expansion between the semiconductor laser and the metal radiator may cause stress or distortion of the semiconductor laser, which may adversely affect the reliability of the semiconductor laser. In order to solve such a problem, a material having a coefficient of thermal expansion relatively close to that of the substrate material of the semiconductor laser, specifically Si, is formed on the metal radiator.
A method of arranging a submount made of, and mounting and fixing a semiconductor laser on it by a solder material is often used.

However, in recent years, high output lasers, multi-beam semiconductor lasers, etc. have been developed one after another in response to the demand for higher speed and smaller size of optical semiconductor devices. Such high-power lasers and multi-beam semiconductor lasers generate more heat than conventional semiconductor lasers, so
The sub-mount consisting of the following had the following problems. That is, since the difference in thermal expansion coefficient between the semiconductor laser and the submount is large, distortion occurs when the semiconductor laser and the submount thermally expand, and the distortion causes the semiconductor laser to bend. In particular, in the multi-beam semiconductor laser, there has been a problem that when the individual laser elements are curved, the polarization planes of the lasers are deviated.

Further, since the semiconductor laser generates a large amount of heat, there is a problem that the laser power fluctuates due to the generated heat. Therefore, as one of the methods for coping with this and obtaining a stable light output, the light emitted from the rear end face opposite to the front end face for extracting the light output in the semiconductor laser light emitting element is used as the monitor light. Conventionally, so-called APC (Auto Power Control) driving is a method of stabilizing the light output by monitoring the intensity of the monitoring light by the light receiving element for monitoring built in the light source chip and performing feedback driving based on this. Known from.

FIG. 6 shows a conventional package structure in a so-called APC driving semiconductor laser device. As is clear from this figure, the mount surfaces of the semiconductor laser device 101 and the monitor light receiving device 102 generally form an angle close to 90 degrees. This is because the emission light of the semiconductor laser element is emitted in the stacking surface direction, that is, in the direction substantially parallel to the mounting surface of the semiconductor laser due to its structure, while the light-receiving surface of the monitor light-receiving element is formed on the element surface. This is because the light incident on the light receiving element must have an angle other than horizontal with respect to the mount surface of the light receiving element in order to guide the light to the element. In the figure, 103 is a stem and 10
4 is a metal cap, and 105 is a transparent glass plate.

However, if such a mounting structure is adopted, the semiconductor laser element 101 and the monitor light receiving element 10 are adopted.
Since the mounting surface is different from that of No. 2, the wire bonding device for electrically connecting the chip and the external lead at the time of manufacturing must use a different device, or the stage portion holding the package must have a rotation mechanism. Therefore, there is a problem that the manufacturing apparatus becomes a complicated mechanism.

In order to solve the above problem, a semiconductor laser device as shown in FIG. 7 has been developed. In such a semiconductor laser device, a Si submount 202 is arranged on a metal plate 201. Then, the semiconductor laser chip 203 is mounted on the upper surface of the end portion of the Si submount 202, and the monitor light receiving element 204 is provided in the other end direction. Here, the positional relationship between the light receiving element 204 and the semiconductor laser chip 203 is the light 2 in the shaded part of the monitor light 207 emitted from the rear surface of the semiconductor laser chip 203.
Only 07a is incident on the light receiving element 204. On the other hand, the light 206 emitted from the front surface of the semiconductor laser chip 203 in the y direction is reflected by the prism 205 and rises in the z direction. With such a structure, since the mounting surfaces of the semiconductor laser chip 203 and the monitor light receiving element 204 are in a plane, a different bonding apparatus is used when wire bonding is performed, or a stage unit having a complicated mechanism is used for the bonding apparatus. There is no need to provide.

However, the semiconductor laser device having the above structure has the following new problems. That is, (a) since the light emitted from the semiconductor laser light emitting element is emitted in the direction parallel to the light receiving portion, the light entering the light receiving element is obliquely incident light emitted from the rear end face of the semiconductor laser light emitting element. Therefore, there is a problem that the size of the light receiving element must be increased in order to monitor the central portion of the output light having the highest light intensity.

Further, (b) since the semiconductor laser light emitting element and the light receiving element are provided on the submount,
The temperature of the submount rises due to heat generation of the light emitting element, and the sensitivity characteristic changes due to the temperature characteristic of the light receiving element. As a result, it is necessary to identify whether the change in the monitor current is due to the change in the light output of the light emitting element or the temperature rise of the light receiving element. There is a problem that it becomes difficult. This becomes a serious problem especially when the optical output of the semiconductor laser is used in an analog manner.

[0010]

DISCLOSURE OF THE INVENTION The present invention can suppress deterioration of reliability of an optical semiconductor device due to heat generation of a light emitting element,
An object of the present invention is to provide an optical semiconductor device which can be easily manufactured industrially. Another object of the present invention is to provide an optical semiconductor device which is smaller than the conventional one and enables more accurate APC driving.

[0011]

The inventors of the present invention have made earnest studies to improve the reduction in reliability of an optical semiconductor device due to heat generation of a light emitting element represented by a semiconductor laser, and as a material for a submount, If a material having a thermal expansion coefficient closer to that of the material forming the light emitting element and a higher thermal conductivity is used instead of Si that has been conventionally used, the above-mentioned conventional heat generation of the light emitting element is caused. We have found that the problems can be solved and the reliability of the optical semiconductor device can be improved. The above knowledge is useful because it is expected that the amount of heat generated by the semiconductor laser will increase as the development of high-power lasers and multi-beam semiconductor lasers progresses in the future.

The present inventor further diligently studied in order to improve the problem of “increasing the size of the device” that occurred in the semiconductor laser device as shown in FIG. 7, and as a result, for a monitor for detecting the light output of the light emitting element. It was found that the device can be downsized by providing the light receiving element on the light emitting direction side (front side) of the light emitting element. For example, if the light receiving element is provided under the beam splitter such as the prism in FIG. 7, there is no need to provide a space for installing the monitor light receiving element on the rear side of the light emitting element, and a new light receiving element is installed on the front side. Since it is not necessary to provide a space, the device can be downsized. The present inventors have made further studies and completed the present invention.

That is, according to the present invention, (1) (a) the thermal conductivity is 150 W / mK or more, and (b) the thermal expansion coefficient is 0 when the thermal expansion coefficient of the material forming the light emitting element is 1. A submount made of a material of 0.55 to 1.5,
An optical semiconductor device, comprising: a light emitting element mounted on the submount; (2) an optical semiconductor device according to (1), wherein the light emitting element is a semiconductor laser; and (3) a semiconductor laser. Is a multi-beam semiconductor laser, and (4) the material forming the submount is III-
(5) The optical semiconductor device according to (1) above, which is a Group V semiconductor compound, and (5) the optical semiconductor according to (1) above, wherein the material forming the submount is AlN. Equipment.

Further, the present invention is (6), wherein the optical semiconductor device further comprises a light receiving element on the light emitting direction side of the light emitting element for detecting the light output of the light emitting element. (7) Optical semiconductor device, (7) The optical semiconductor device according to (6), wherein the light receiving element is a photodiode, (8) Further, the light beam emitted from the light emitting element is separated into a plurality of light beams, and some of the light beams are separated. (9) The optical semiconductor device according to (6) above, characterized in that it has a beam splitter for guiding light to the light receiving element on the light emitting direction side of the light emitting element, and (9) the beam splitter is a prism. The optical semiconductor device according to (8) above.
(10) The optical semiconductor device according to (9) above, wherein the prism is mounted on the light receiving element.
(11) The optical semiconductor device according to (10), wherein the prism is mounted on the light receiving element using an adhesive having a smaller refractive index than the prism.
2) The optical semiconductor according to the above (10), wherein the prism has a reflecting surface such that an incident angle φ _{c of} a part of the light separated by the prism on the light receiving element can satisfy the following formula. Device, φ _c <sin ⁻¹ (n ₂ / n ₁ ) Equation 1 (where n ₁ is the refractive index of the prism, n ₂ is the refractive index of the adhesive used to mount the prism,) ( 13) The light receiving element is provided on the side of the prism opposite to the light emitting element without being covered by the prism, and the light receiving element is a part of the light separated by the prism, and further on the rear surface of the prism. The optical semiconductor device as described in (9) above, which is provided at a position where refracted light can be detected.

The present invention also provides (14) a light emitting device,
An optical semiconductor device, comprising: a light receiving element that detects the light output of the light emitting element on the light emitting direction side of the light emitting element; (15) The light according to (14), wherein the light receiving element is a photodiode. Semiconductor device, (16) The optical semiconductor device according to (14), wherein the light emitting element is a semiconductor laser, (17) The semiconductor laser according to (16), wherein the semiconductor laser is a multi-beam semiconductor laser. (18) An optical semiconductor device, further comprising a beam splitter which separates a light beam emitted from a light emitting element into a plurality of light beams and can guide a part of the light beam to a light receiving element on a light emitting direction side of the light emitting element. (19) The beam splitter according to (14),
(18) The optical semiconductor device according to (18), which is a prism, (20) The optical semiconductor device according to (19), wherein the prism is mounted on a light receiving element, (21) The optical semiconductor device according to (20) above, wherein the prism is mounted on the light receiving element using an adhesive having a smaller refractive index than the prism, and (22) the prism is The optical semiconductor device according to the above (20), wherein the optical semiconductor device has a reflection surface that allows an incident angle φ _{c of} a part of the light separated by the prism to the light receiving element to satisfy the following formula: φ _c < sin ⁻¹ (n ₂ / n ₁ ) Formula 1 (where n ₁ is the refractive index of the prism, n ₂ is the refractive index of the adhesive used to mount the prism,) (23) , On the opposite side of the prism from the light emitting element It is provided without being covered by the rhythm, and the light receiving element is provided at a position where it can detect a part of the light separated by the prism and further the light refracted by the rear surface of the prism can be detected. The present invention relates to the optical semiconductor device described in (19) above.

(24) (a) the substrate, (b) the submount mounted on the substrate, (c) the semiconductor laser mounted on the submount, and (d) the substrate. A light receiving element provided on the front end face side of the semiconductor laser, and (e) a beam splitter capable of separating a light beam emitted from the semiconductor laser into a plurality of light beams and guiding some of the light beams to the light receiving element. An optical semiconductor device having: a material of the submount having a thermal conductivity of 150 W / mK or more, and a material of the submount having a thermal expansion coefficient of thermal expansion of a material of the semiconductor laser. 0.55 to 1.5 when the coefficient is 1.
(25) The optical semiconductor device according to (24), wherein the beam splitter is a prism, and (26) the prism is mounted on a light receiving element. (27) The optical semiconductor device according to (25), wherein the prism is mounted on the light receiving element using an adhesive having a refractive index smaller than that of the prism. To (2
(28) The optical semiconductor device according to (6), wherein the prism has a reflecting surface that allows an incident angle φ _{c of} a part of the light separated by the prism to the light receiving element to satisfy the following expression. The optical semiconductor device according to (26) above, wherein φ _c <sin ⁻¹ (n ₂ / n ₁ ) Formula 1 (wherein, n ₁ is a refractive index of the prism, and n ₂ is used to mount the prism. The refractive index of the adhesive is shown.) (29) The light receiving element is provided on the opposite side of the prism from the light emitting element without being covered by the prism, and the light receiving element is (30) (a) The thermal conductivity is 150, which is a part of the optical semiconductor device and is further provided at a position where the light refracted by the rear surface of the prism can be detected.
W / mK or more, and (b) is made of a material having a coefficient of thermal expansion of 0.55 to 1.5 when the coefficient of thermal expansion of the material forming the light emitting element to be combined is 1. About mount,

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The optical semiconductor device according to the present invention preferably has a structure in which a light emitting element is mounted on a submount (hereinafter also referred to as "mount"). Here, the light emitting element may be a known element, but is preferably a semiconductor laser, more preferably a high power semiconductor laser or a multi-beam semiconductor laser. As the high-power semiconductor laser, for example, a broad area type semiconductor laser, preferably an optical output of about 10 is used.
A broad area type semiconductor laser having a power of about W or more, or a narrow stripe type semiconductor laser having an optical output of about 200 mW or more can be used. Examples of the multi-beam semiconductor laser include a semiconductor laser in which a plurality of semiconductor laser elements are integrated, and preferably a semiconductor laser in which a plurality of semiconductor laser elements are monolithically integrated.

The submount forming the optical semiconductor device of the present invention has a thermal expansion coefficient close to that of the material forming the light emitting element,
It is also characterized by being made of a material with high thermal conductivity. The above "materials having a thermal expansion coefficient close to that of the material forming the light emitting element"
Specifically, when the coefficient of thermal expansion of the material forming the light emitting element is converted to 1, the converted value of the coefficient of thermal expansion is about 0.
About 55 to 1.5, preferably about 0.6 to 1.4,
More preferably, the material is about 0.65 to 1.35, and most preferably about 0.65 to 1. Further, as a "material having high thermal conductivity", specifically, the thermal conductivity is about 150 W / mK or more, preferably about 170 W / m.
Materials having a K or higher, more preferably about 190 W / mK or higher are included. With the submount made of the above material, for example, distortion caused by thermal expansion of the semiconductor laser and the submount can be suppressed as compared with the conventionally used Si submount, and the curvature of the semiconductor laser due to such distortion can be suppressed. The reliability of the light emitting element is improved.

As a submount material having the above characteristics, a III-V semiconductor compound is specifically mentioned as a preferable example. The III-V group semiconductor compound has a chemical formula of In _a Al _b Ga _c N _x As _y P _z (a, b, c ≦
1, a + b + c = 1, x, y, z ≦ 1, x + y + z =
In 1), it is based on a semiconductor containing all semiconductors having composition ratios a, b and c and x, y and z changed within the respective ranges. In addition, some of the group III elements In, Al, and Ga are replaced with B, and V
A group in which a part of the group elements N, As, and P are replaced with Sb is also included. Above all, a nitride semiconductor compound is more preferable as the submount material. In the above chemical formula, the nitride semiconductor compound means that any one of the above three elements (In, Al, Ga) is included in the group 3 element and N (nitrogen) is included in the group 5 element. Refers to a compound that exists.

Further, the submount material is A
In is particularly preferred. The III-V group semiconductor compound is often used as a material for the semiconductor laser. Typical examples of such compounds include GaAs and I
The thermal expansion coefficient and thermal conductivity of nP are shown in the table below. The thermal expansion coefficient and thermal conductivity of AlN and Si are also shown in the table below. As is clear from the table below, AlN is more GaAs and I than Si.
It has a thermal expansion coefficient close to that of nP and a high thermal conductivity. Therefore, AlN is suitable as the submount material according to the present invention.

[0021]

[Table 1]

The optical semiconductor device according to the present invention may have another known structure in addition to the above structure. Among them, since the light output of the light emitting element fluctuates due to the heat generation of the light emitting element as described above, the optical semiconductor device according to the present invention includes a light receiving element that detects the light output of the light emitting element (hereinafter, “monitor light receiving element”). Which is called "APC (Auto Power Contr), which can obtain a stable light output by monitoring the light intensity of the light emitting element by the light receiving element for monitoring and performing feedback drive based on this.
ol) driven optical semiconductor devices are preferred. Here, the light receiving element is not particularly limited, but a photodiode is preferably used. The photodiode may be known.

As the APC-driven optical semiconductor device,
An optical semiconductor device having a light receiving element for monitoring on the light emitting direction side of the light emitting element is preferable. Here, the light emitting direction side refers to a side from which a light beam to be extracted as a light output is emitted, and is also called a front side. The emission direction side has the same meaning as the front end face side in the semiconductor laser. With such a structure, it is not necessary to install the monitor light receiving element on the side (rear side) opposite to the light emitting direction of the light emitting element unlike the conventional optical semiconductor device shown in FIG. Has the advantage that it can be miniaturized.

The optical semiconductor device according to the present invention may have any structure as long as it has a monitor light receiving element on the light emitting direction side of the light emitting element. However, in order to allow the light-receiving element for monitoring on the light-emitting direction side of the light-emitting element to efficiently detect the light output of the light-emitting element, the optical semiconductor device includes a plurality of light rays emitted from the light-emitting element. It is more preferable to have a structure in which a beam splitter capable of separating some of the light rays into the light receiving element is provided on the light emitting direction side of the light emitting element. The beam splitter is not particularly limited, and known ones such as mirrors and prisms may be used. Above all, it is preferable to use a prism. Such a prism has a reflectance of, for example, about 70 made of a dielectric multilayer film on the reflecting surface.
It is particularly preferable that a half mirror of about 90% is provided. Here, the reflection surface refers to a surface on which the light emitted from the light emitting element strikes.

A preferred embodiment of the above optical semiconductor device having a light emitting element, a light receiving element and a beam splitter is shown in FIG.
Will be described in detail. In the optical semiconductor device shown in FIG. 1, a semiconductor laser 11 is used as a light emitting element, a photodiode 15 is used as a light receiving element, and a prism 14 is used as a beam splitter. In the optical semiconductor device, (a) the semiconductor laser 11 is mounted on the submount 12 so that the emitted light beam is substantially parallel to the substrate 13.
The photodiode 15 is mounted on the substrate 13 on which the submount 12 is mounted (b).
Is provided on the front end face side of the semiconductor laser 11, and (c) the light beam emitted from the semiconductor laser 11 is separated into two light beams 16 and 17, and one of the light beams 17 can be guided to the photodiode 15. A prism 14 that can be formed is provided so as to cover the photodiode 15.

In the optical semiconductor device of the above aspect, the substrate 1
Although 3 is not particularly limited, it is preferable to use a Si substrate. Further, the submount 12 has a thermal expansion coefficient close to that of the above-mentioned material forming the semiconductor laser,
It is preferable to use a submount made of a material having high thermal conductivity. The semiconductor laser 11 which is a light emitting element is not particularly limited, but it is preferable to use a high-power semiconductor laser or a multi-beam semiconductor laser as described above. The photodiode 15, which is a light receiving element, may be formed of a part of the substrate, or may be formed of a semiconductor film laminated on the substrate. The former is particularly preferable in the present invention.

The prism 14 is preferably mounted on the substrate 13 with an adhesive having a smaller refractive index than the prism. Further, the adhesive is preferably colorless and transparent. In order to prevent a decrease in received light intensity due to total reflection of at least a part of the light beam 17 at the interface between the prism and the adhesive and not incidence on the photodiode 15, the refractive index of the adhesive for mounting the prism is It is preferably smaller than the refractive index. Specifically, the ratio of the refractive index of the prism _{n 1} and the refractive index _{n 2} of said adhesive _(n 2 / _{n 1)} is smaller than 1, preferably about 0.9
It is suitable that it is not more than about 0.8, more preferably not more than about 0.8. The adhesive for mounting the prism is not particularly limited as long as it satisfies the above conditions, and known adhesives such as epoxy resin (including modified products), silicone resin or polyimide resin may be used.

The prism 14 is formed by using the adhesive as described above.
Is mounted on substrate 13, prism 1
The inclination angle of the reflecting surface of No. 4 is not particularly limited. Above all, as the prism 14, a prism having a reflecting surface inclined at 45 degrees is preferable. As described above, by using the prism having the reflecting surface inclined at 45 degrees, the light beam 16 emitted from the semiconductor laser 11 rises in a direction substantially perpendicular to the substrate surface, so that the deviation of the optical axis is small. There are advantages such as that, and that two-dimensional integration is possible.

As the optical semiconductor device of the above aspect according to the present invention, the prism 14 having a reflecting surface having the following inclination can be used without mounting the above-mentioned adhesive when mounting the prism 14. An optical semiconductor device provided is also mentioned as a preferable embodiment. That is, the prism 14 having a reflecting surface whose inclination angle is adjusted so that the incident angle φ _{c of} a part of the light 17 separated by the prism 14 on the photodiode 15 can satisfy the following formula is provided. Optical semiconductor device. φ _c <sin ⁻¹ (n ₂ / n ₁ ) Formula 1 (where n ₁ is the refractive index of the prism, and n ₂ is the refractive index of the adhesive that mounts the prism). As a result, there is an advantage that at least a part of the light beam 17 is totally reflected at the interface between the prism and the adhesive, and the reduction of the received light intensity due to not being incident on the photodiode 15 can be prevented.

A more preferable embodiment of the optical semiconductor device according to the present invention having a light emitting element, a light receiving element and a beam splitter will be described in detail with reference to FIG. In the optical semiconductor device shown in FIG. 2, similarly to the optical semiconductor device shown in FIG. 1, a semiconductor laser 11 is used as a light emitting element, a photodiode 15 is used as a light receiving element, and a prism 14 is used as a beam splitter.

The difference between such an optical semiconductor device and the optical semiconductor device shown in FIG. 1 is that the length of the prism 14 is shortened and the photodiode 15 has the semiconductor laser 11 of the prism 14.
That is, the prism 14 is provided on the side opposite to that, without being covered by the prism 14. With such a structure, the light beam 17
Is further refracted on the rear surface of the prism 14 (the surface facing the reflecting surface) and enters the photodiode 15. As a result, it is not always necessary to select an adhesive for mounting the prism or adjust the inclination of the reflecting surface of the prism as described above, and at least a part of the light beam 17 is totally reflected on the lower surface of the prism. By doing so, it is possible to prevent the loss of the amount of light incident on the photodiode, and there is an advantage that the received light intensity is improved. In addition, the reflectance on the reflecting surface of the prism can be increased to increase the output of the light 16 upward. Also, FIG.
As is clear from the above, since the incident angle to the photodiode is small, the size of the photodiode can be reduced,
Combined with the fact that the length of the prism can be shortened, there is also an advantage that the device can be downsized.

The optical semiconductor device according to the present invention can be easily manufactured by a means known per se. A preferred method of manufacturing the optical semiconductor device shown in FIG. 2 will be described below as one embodiment of the method of manufacturing the optical semiconductor device according to the present invention.
In this embodiment, as shown in FIG. 3, a semiconductor laser in which two laser elements A and B are formed on the same substrate is used as a light emitting element. First, a method of manufacturing the semiconductor laser will be described. First, as shown in FIG. 4A, for example, metal organic vapor phase epitaxial growth (M
OVPE) and other known epitaxial growth methods are used to form a buffer layer 2 made of n-GaAs, for example n-Al, on a substrate 1 made of n-GaAs.
An n-clad layer 3 made of GaAs (referred to as 3a in the element A and 3b in the element B), for example, GaAs
Active layer 4 having a multiple quantum well structure including layers (referred to as 4a in the device A and 4b in the device B), for example, p-A
p-clad layer 5 made of 1GaAs (referred to as 5a in the element A and 5b in the element B), for example, p-G
a cap layer 6 made of aAs (6a in the element A,
In the element B, 6b) are sequentially stacked.

Next, as shown in FIG. 4 (b), the laser elements A and B are protected by a resist (not shown), and then wet etching is performed using, for example, a hydrochloric acid-based solution to form a buffer layer. A trench reaching 2 is formed. This separates the laser diodes.

Next, as shown in FIG. 5 (a), a portion of each laser diode which becomes a current injection region is protected by a resist (not shown), and the p-cladding layers 5a and 5b are formed.
N-type impurities are ion-implanted into the surface of the. As a result, high resistance layers 7a and 7b are formed in the ion-implanted region,
It becomes a gain guide type current constriction structure. Next, FIG.
As shown in (b), a laminated film of, for example, Ti / Pt / Au is formed on the cap layers 6a and 6b by sputtering, and p-type electrodes 8a and 8 are formed on the laser elements A and B, respectively.
b is formed. On the surface of the substrate 1 opposite to the side on which the laser elements A and B are formed, for example, AuGe / Ni / Au
The laminated film of is formed by sputtering to form the n-type electrode 9. After that, through a pelletizing process, a semiconductor laser having the sectional structure shown in FIG. 3 having laser elements A and B on the same substrate 1 can be obtained.

Semiconductor laser 1 obtained as described above
1 is fixed on a submount 12 made of AlN. Submount 12 on which the semiconductor laser 11 is mounted
Are fixed on the silicon substrate 13. The prism 14 made of glass is fixed on the silicon substrate in the laser emission direction. Here, the prism is provided with a 45-degree mirror having an arbitrary reflectance and can reflect a part 16 of the laser light on the upper surface. On the other hand, the light 17 refracted by the prism passes through the prism, is refracted further on the rear surface of the prism, and reaches the silicon substrate. The photodiode 15 is built in this portion. As described above, the optical semiconductor device according to the present invention shown in FIG. 2 can be manufactured.

[0036]

According to the optical semiconductor device of the present invention,
The reliability of the light emitting element due to the large difference in the thermal expansion coefficient between the light emitting element and the submount by using the submount made of a material having a thermal expansion coefficient closer to that of the material forming the light emitting element and having a higher thermal conductivity. It is possible to prevent the deterioration of the property, for example, the bending of the semiconductor laser which is a light emitting element, the deviation of the polarization plane between the lasers in the multi-beam semiconductor laser, and the like. Further, in the so-called APC driven optical semiconductor device, it is possible to reduce the influence of the temperature rise of the light receiving element on the change of the monitor current, and it is possible to monitor the optical output more accurately. This is particularly useful when the optical output of the semiconductor laser is used in analog.

In the APC-driven optical semiconductor device according to the present invention, the monitor light receiving element for detecting the light output of the light emitting element is provided on the light emitting direction side (front side) of the light emitting element, so that the device can be miniaturized. It also has the advantage.

[Brief description of drawings]

FIG. 1 is a diagram showing one embodiment of an optical semiconductor device according to the present invention.

FIG. 2 is a diagram showing another aspect of the optical semiconductor device according to the present invention.

FIG. 3 is a cross-sectional view of a semiconductor laser preferably used as a light emitting element in the optical semiconductor device according to the present invention.

FIG. 4 is a diagram showing a manufacturing process of the semiconductor laser shown in FIG.

FIG. 5 is a diagram showing a manufacturing process of the semiconductor laser shown in FIG.

FIG. 6A is a perspective view showing one aspect of a conventional package structure in an APC driven semiconductor laser device. (B) is yz of the package structure shown in FIG.
It is sectional drawing cut | disconnected by the plane containing an axis | shaft.

FIG. 7A is a perspective view showing another aspect of the conventional package structure in the APC driving semiconductor laser device. (B) is yz of the package structure shown in FIG.
It is sectional drawing cut | disconnected by the plane containing an axis | shaft.

[Explanation of symbols]

11 Semiconductor laser 12 submount 13 board 14 Prism 15 photodiode 101, 203 Semiconductor laser 102,204 Light receiving element for monitor

Claims (17)

[Claims] 1. The thermal conductivity of (a) is 150 W / mK or more, and (b) the coefficient of thermal expansion of the material forming the light emitting element is 1 or less.
An optical semiconductor device comprising: a submount made of a material having a coefficient of thermal expansion of 0.55 to 1.5 in the case of, and a light emitting element mounted on the submount. 2. The optical semiconductor device according to claim 1, wherein the light emitting element is a semiconductor laser. 3. The optical semiconductor device according to claim 2, wherein the semiconductor laser is a multi-beam semiconductor laser. 4. The material constituting the submount is III-
The optical semiconductor device according to claim 1, wherein the optical semiconductor device is a group V semiconductor compound. 5. The material forming the submount is AlN.
The optical semiconductor device according to claim 1, wherein 6. An optical semiconductor device comprising a light emitting element and a light receiving element for detecting the light output of the light emitting element on the light emitting direction side of the light emitting element. 7. The optical semiconductor device according to claim 6, wherein the light receiving element is a photodiode. 8. The optical semiconductor device according to claim 6, wherein the light emitting element is a semiconductor laser. 9. The optical semiconductor device according to claim 8, wherein the semiconductor laser is a multi-beam semiconductor laser. 10. The light emitting element further comprises a beam splitter on the light emitting direction side of the light emitting element, which splits the light ray emitted from the light emitting element into a plurality of light rays and can guide a part of the light rays to the light receiving element. The optical semiconductor device according to claim 6. 11. The optical semiconductor device according to claim 10, wherein the beam splitter is a prism. 12. The optical semiconductor device according to claim 11, wherein the prism is mounted on the light receiving element. 13. The optical semiconductor device according to claim 12, wherein the prism is mounted on the light receiving element using an adhesive having a refractive index smaller than that of the prism. 14. The prism according to claim 12, wherein the prism has a reflecting surface such that an incident angle φ _{c of} a part of the light separated by the prism on the light receiving element can satisfy the following expression. Optical semiconductor device. φ _c <sin ⁻¹ (n ₂ / n ₁ ) Formula 1 (where n ₁ is the refractive index of the prism, and n ₂ is the refractive index of the adhesive used to mount the prism.) 15. A light receiving element is provided on the side of the prism opposite to the light emitting element without being covered by the prism, and the light receiving element is a part of the light separated by the prism, 12. The prism is provided at a position where the light refracted by the rear surface can be detected.
The optical semiconductor device according to. 16. (a) a substrate, (b) a submount mounted on the substrate, (c) a semiconductor laser mounted on the submount, and (d) on the substrate, A light receiving element provided on the front end face side of the semiconductor laser; and (e) a beam splitter capable of separating the light beam emitted from the semiconductor laser into a plurality of light beams and guiding some of the light beams to the light receiving element. In the optical semiconductor device having the above, the thermal conductivity of the material forming the submount is 150 W / mK or more, and the thermal expansion coefficient of the material forming the submount is the thermal expansion coefficient of the material forming the semiconductor laser. The optical semiconductor device is 0.55 to 1.5 when 1 is 1. 17. A thermal expansion coefficient of 0.55 or more when (a) the thermal conductivity is 150 W / mK or more, and (b) the thermal expansion coefficient of the material constituting the light emitting element to be combined is 1.
A submount comprising a material that is ~ 1.5.