JP3596659B2 - Tunable semiconductor laser and optical integrated device using the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wavelength tunable semiconductor laser used in the optical communication field and the optical information processing field (optical disc, display, etc.), an optical integrated device composed of the wavelength tunable semiconductor laser and an optical waveguide device, and their manufacture. About the method. In particular, the present invention relates to a configuration of an integrated short-wavelength light source including a semiconductor laser chip including the above-described wavelength-tunable semiconductor laser and an optical waveguide type wavelength conversion device, and a method of manufacturing the same.
[0002]
[Prior art]
In the field of optical communication, development of a small and low-cost optical module in which a semiconductor laser, an electronic element, an optical fiber, and the like are hybrid-integrated on a silica-based lightwave circuit platform is regarded as important.
[0003]
What is important here is to fix each element with high positional accuracy and minimize the transmission loss. For this purpose, a surface mount type optical module in which a semiconductor laser and a single mode fiber are directly coupled using a Si-V groove substrate has been realized (1997 IEICE General Conference, C-3). -63). In this technique, a marker is formed on the Si substrate and the semiconductor laser element, the center of the V-groove and the light emitting point of the semiconductor laser element are detected by recognizing the marker, and the positioning is adjusted with high accuracy, thereby reducing the mounting variation. Is suppressed to about ± 0.61 μm in the x direction and to about ± 1 μm in the z direction.
[0004]
In the field of optical information processing, a small-sized short-wavelength light source is required in order to realize a high-density optical disc and a high-definition display. As a technique for realizing a shorter wavelength, a second harmonic generation (hereinafter, “SHG”) using a semiconductor laser and a quasi-phase matching (hereinafter, referred to as “QPM”) type optical waveguide type wavelength conversion device is known. (See, for example, Yamamoto, et al .: Optics Letters, Vol. 16, No. 15, p. 1156 (1991)).
[0005]
FIG. 1 shows a schematic configuration diagram of a blue light source using an optical waveguide type wavelength conversion device.
[0006]
In the configuration shown in FIG. 1, a tunable semiconductor laser 110 having a distributed Bragg reflection (hereinafter, referred to as “DBR”) region is used as the semiconductor laser 110. Hereinafter, a wavelength tunable semiconductor laser having a DBR region is referred to as a “DBR semiconductor laser” or a “DBR laser”.
[0007]
The DBR semiconductor laser 110 is, for example, a 100 mW-class AlGaAs-based DBR semiconductor laser 110 in a 0.85 μm band, and includes an active layer region 112 and a DBR region 111. By changing the injection current into the DBR region 111, the oscillation wavelength can be changed.
[0008]
On the other hand, an optical waveguide type wavelength conversion device 116 which is a wavelength conversion element is an X-plate MgO-doped LiNbO₃It is composed of an optical waveguide 115 formed on a substrate 113 and a periodically poled region 114. The semiconductor laser 110 and the wavelength conversion device 116 are fixed on the submounts 117 and 118 by junction-up, respectively.
[0009]
Laser light obtained from the emission end face of the DBR semiconductor laser 110 is directly coupled to the optical waveguide 115 of the optical waveguide type wavelength conversion device 116. Specifically, by adjusting the positional relationship between the DBR semiconductor laser 110 and the optical waveguide type wavelength conversion device 116 on the submounts 117 and 118, the laser output of about 100 mW from the semiconductor laser 110 is reduced to about 60 mW. Is coupled to the optical waveguide 115 of the wavelength conversion device 116. Furthermore, by controlling the amount of current injected into the DBR region 111 of the DBR semiconductor laser 110, its oscillation wavelength is fixed within the tolerance of the phase matching wavelength of the optical waveguide type wavelength conversion device 116. With such a configuration, blue light having a wavelength of 425 nm can be obtained with an output of about 10 mW at present.
[0010]
FIG. 2 is a schematic configuration diagram of a blue light source using a domain-inverted waveguide device.
[0011]
The DBR semiconductor laser 221 (100 mW-class AlGaAs-based DBR semiconductor laser in the 0.85 μm band) is provided with a DBR unit 228 for fixing the oscillation wavelength, and the oscillation wavelength is further variable inside the DBR unit 228. An internal heater (not shown) is formed for performing the operation. On the other hand, the domain-inverted waveguide device 224, which is a wavelength conversion element, is an X-plate MgO-doped LiNbO₃It comprises an optical waveguide 226 formed on a substrate 225 and a periodically poled region 227.
[0012]
The laser light 229 emitted from the semiconductor laser 221 and made parallel by the collimator lens 222 (numerical aperture NA = 0.5) is transmitted to the polarization inversion waveguide device 224 by the focusing lens 223 (numerical aperture NA = 0.5). The light is focused on the end face of the optical waveguide 226 and is coupled to the optical waveguide 226 having the domain-inverted region 227. Specifically, about 70 mW of laser light can be coupled to the optical waveguide 226 for a laser output of about 100 mW. Also in this configuration, the amount of current injected into the DBR section 228 of the DBR semiconductor laser 221 is controlled to fix the oscillation wavelength within the tolerance of the phase matching wavelength of the domain-inverted waveguide device 224.
[0013]
Since the output of the obtained blue light increases in proportion to the square of the output of the laser light coupled to the optical waveguide 226, the coupling efficiency is a very important factor for obtaining a high output blue light. .
[0014]
[Problems to be solved by the invention]
In the case of a surface mount type optical module by directly coupling a semiconductor laser and a single mode fiber, in order to couple the light of the semiconductor laser into the optical fiber with high efficiency, the x direction and the y direction parallel to the cross section of the optical fiber are required. The position adjustment accuracy is required on the order of submicron, and on the order of several microns in the z direction along the optical axis of the optical fiber. In this case, the optical fiber is fixed with high accuracy by the V-groove. Also, in the x-direction parallel to the surface of the mounting substrate and in the z-direction along the optical axis of the optical fiber, the semiconductor laser chip also generally achieves highly accurate positioning adjustment in the prior art. ing. However, regarding the positioning of the semiconductor laser chip in the y direction in the cross section of the optical fiber and perpendicular to the surface of the mounting substrate, the positioning adjustment is generally performed with submicron accuracy or less due to the presence of a solder layer for fixing. And fixing is difficult.
[0015]
On the other hand, in a short wavelength light source composed of a semiconductor laser and an optical waveguide type wavelength conversion element (optical waveguide device), a lens-coupled module as shown in FIG. 2 has been realized at present. However, when such a short-wavelength light source is applied to the consumer field, the miniaturization and cost reduction of the light source are indispensable. Adjustment is necessary, and its mass productivity is low. In addition, miniaturization of the entire configuration is limited to miniaturization of about several cc. As a technology for realizing further miniaturization, there is a direct coupling technology. However, in order to further reduce the cost of the direct coupling type module, a modularization technology which is more mass-producible and can be positioned with high accuracy is required. You.
[0016]
The divergence angle of a semiconductor laser is generally small in a direction parallel to the surface of the mounting substrate (x direction) and large in a direction perpendicular to the substrate surface (y direction). Similarly, the divergence angle of the optical waveguide produced by the proton exchange method is small in a direction parallel to the surface of the mounting substrate (x direction) and large in a direction perpendicular to the substrate surface (y direction). Therefore, the positioning adjustment accuracy in the direction (y direction) perpendicular to the substrate surface becomes severe, and an adjustment accuracy of submicron or less is required. That is, it is necessary to control the height from the submount on which the semiconductor laser is mounted to the active layer with high precision. However, the thickness of a GaAs substrate generally used as a substrate in an AlGaAs semiconductor laser is not usually controlled with submicron accuracy. On the other hand, the thickness of an epitaxial layer such as an active layer and the thickness of an electrode are controlled with high precision. Therefore, in order to control the position in the height direction (y direction) with high accuracy, the semiconductor laser is mounted with junction down (the direction in which the surface on which the active layer is formed (epitaxial surface) is in contact with the submount). There is a need.
[0017]
Further, in a semiconductor laser mounted by junction-up, the heat radiation state of the active layer region is not good, so that the reliability of the laser is not sufficient. From this point of view, junction-down mounting is required.
[0018]
However, a DBR semiconductor laser as a wavelength tunable semiconductor laser constituting an optical waveguide integrated light source changes an oscillation wavelength by controlling an amount of current injected into a DBR region. Specifically, the wavelength of the light fed back from the DBR region is varied by changing the temperature of the DBR region by current injection and changing the refractive index as a result. According to this principle, the heat radiation state of the DBR region is improved at the time of junction-down mounting, so that it is rather difficult to realize variable control of the wavelength.
[0019]
Also, in fixing the optical waveguide device, it is impossible to use a configuration such as a V-groove at the time of fixing the optical fiber, so that high-precision positioning adjustment is required particularly in the y direction.
[0020]
Accordingly, the present invention has been made to solve the above-described problems, and has the following objects. (1) A wavelength-tunable semiconductor laser capable of achieving a stable wavelength-tunable operation even when mounted in a junction-down manner. (2) In an optical integrated device composed of a semiconductor laser chip including a wavelength tunable semiconductor laser as described above and an optical waveguide device, the mounting accuracy in the substrate thickness direction is improved. To provide an optical integrated device capable of coupling laser light from a chip to an optical waveguide of an optical waveguide device with high efficiency. (3) An array-type semiconductor laser chip having two or more light-emitting portions and two or more An optical integrated device that can adjust a large number of optical couplings simultaneously with high efficiency, easily and in a short time by using an optical waveguide device having a plurality of optical waveguides. (4) To provide a method for manufacturing an optical integrated device capable of easily manufacturing an optical integrated device having the above-described characteristics with high mass productivity, and (5) In particular, an optical waveguide device as an optical waveguide device. It is an object of the present invention to realize an ultra-compact short-wavelength light source that emits light in a blue region to a green region by using a wavelength-converting device.
[0021]
[Means for Solving the Problems]
The wavelength tunable semiconductor laser of the present invention includes a submount, a semiconductor laser chip having at least an active layer region and a distributed Bragg reflection region mounted on the submount, and the semiconductor laser chip includes: It is mounted on the submount such that the epitaxial growth surface faces the submount, and the heat dissipation state of the active layer region and the heat dissipation state of the distributed Bragg reflection region are different, whereby the Is achieved.
[0022]
In one embodiment, a contact area of the active layer region with the submount is different from a contact area of the distributed Bragg reflection region with the submount.
[0023]
Another wavelength tunable semiconductor laser of the present invention includes a submount, and a semiconductor laser chip mounted on the submount and having at least an active layer region and a distributed Bragg reflection region, the semiconductor laser chip Is mounted on the submount such that the epitaxial growth surface faces the submount and only the active layer region is in contact with the submount, thereby achieving the aforementioned object. .
[0024]
Still another wavelength tunable semiconductor laser according to the present invention comprises a submount, and a semiconductor laser chip mounted on the submount and having at least an active layer region and a distributed Bragg reflection region, The chip is mounted on the submount such that the epitaxial growth surface faces the submount, and the constituent material of the first portion of the submount that the active layer region is in contact with and the distributed Bragg reflection. The constituent material of the second portion in contact with the region is different, thereby achieving the above-described object.
[0025]
In one embodiment, the first portion of the submount has a different coefficient of thermal conductivity from the second portion.
[0026]
An optical integrated device of the present invention has at least a semiconductor laser and an optical waveguide device mounted on a submount, and the semiconductor laser is a wavelength tunable semiconductor laser having the characteristics described above. Thereby, the above-mentioned object is achieved.
[0027]
Another optical integrated device of the present invention includes a submount, a semiconductor laser chip and an optical waveguide element fixed on the submount, and the semiconductor laser chip is fixed on a surface of the submount. A groove is formed in at least one of the portion to be fixed and the portion to which the optical waveguide element is fixed, and a fixing member for fixing the semiconductor laser chip or the optical waveguide element is provided inside the groove, and Thereby, the above-mentioned object is achieved.
[0028]
The fixing member may be solder. Alternatively, the fixing member may be an adhesive.
[0029]
Preferably, a volume of the fixing member after fixing the semiconductor laser chip or the optical waveguide element is smaller than a volume of the groove.
[0030]
Preferably, the groove is located below a light emitting area of the semiconductor laser chip.
[0031]
In one embodiment, the semiconductor laser chip is fixed to the submount such that the surface on the active layer side faces the submount.
[0032]
In one embodiment, the optical waveguide device is an optical fiber.
[0033]
In one embodiment, the optical waveguide device is a wavelength conversion device that converts laser light emitted from the semiconductor laser chip into light having a half wavelength.
[0034]
In one embodiment, the semiconductor laser chip is a distributed Bragg reflection semiconductor laser chip having an active layer region and a distributed Bragg reflection region.
[0035]
In one embodiment, the semiconductor laser chip oscillates with polarized light in TE mode, and the optical waveguide of the optical waveguide element propagates light in TE mode.
[0036]
In one embodiment, the optical waveguide device is fixed to the submount after the semiconductor laser chip is fixed to the submount.
[0037]
In one embodiment, the optical waveguide device is a planar optical waveguide device.
[0038]
In one embodiment, the planar optical waveguide device has an optical waveguide formed on a surface of a dielectric substrate or a ferroelectric substrate.
[0039]
In one embodiment, a relief groove of the fixing member is further formed on the surface of the submount, following the groove.
[0040]
Still another optical integrated device of the present invention includes a submount, a semiconductor laser chip and a planar optical waveguide element fixed on the submount, and the planar optical waveguide element is provided on the submount. It is immobilized on the surface by molecular bonding forces, thereby achieving the above-mentioned object.
[0041]
In one embodiment, the submount is made of silicon, and its surface is oxidized.
[0042]
In one embodiment, the semiconductor laser chip is fixed to the submount such that the surface on the active layer side faces the submount.
[0043]
In one embodiment, the planar optical waveguide device is a wavelength conversion device that converts laser light emitted from the semiconductor laser chip into light having a half wavelength.
[0044]
In one embodiment, the semiconductor laser chip is a distributed Bragg reflection semiconductor laser chip having an active layer region and a distributed Bragg reflection region.
[0045]
In one embodiment, the semiconductor laser chip oscillates with polarized light in the TE mode, and the optical waveguide of the planar optical waveguide element propagates light in the TE mode.
[0046]
In one embodiment, the planar optical waveguide device has an optical waveguide formed on a surface of a dielectric substrate or a ferroelectric substrate.
[0047]
A wavelength tunable semiconductor laser provided according to another aspect of the present invention includes a submount, and a semiconductor laser chip having at least an active layer region and a distributed Bragg reflection region mounted on the submount. The semiconductor laser chip is mounted such that an epitaxial growth surface faces the submount, and the surface of the submount electrically connects the active layer region and the distributed Bragg reflection region of the semiconductor laser chip. A separating groove is provided, which achieves the above-mentioned object.
[0048]
According to another aspect of the present invention, there is provided an optical integrated device comprising: a submount; an array-type semiconductor laser chip having two or more light-emitting portions mounted on the submount; A planar optical waveguide element having a waveguide, wherein the interval between the light emitting portions of the array type semiconductor laser chip and the interval between the optical waveguides of the planar optical waveguide element are equal to each other. Is achieved.
[0049]
In one embodiment, the array-type semiconductor laser chip is fixed to the submount such that the surface on the active layer side faces the submount.
[0050]
In one embodiment, the planar optical waveguide device is a wavelength conversion device that converts laser light emitted from the array semiconductor laser chip into light having a half wavelength.
[0051]
In one embodiment, the array type semiconductor laser chip is a distributed Bragg reflection type semiconductor laser chip having an active layer region and a distributed Bragg reflection region.
[0052]
In one embodiment, the array-type semiconductor laser chip oscillates with TE-mode polarized light, and the optical waveguide of the planar optical waveguide element propagates TE-mode light.
[0053]
In one embodiment, the planar optical waveguide device has an optical waveguide formed on a surface of a dielectric substrate or a ferroelectric substrate.
[0054]
In one embodiment, a distance between the light emitting portions of the array-type semiconductor laser chip and a distance between the optical waveguides of the planar optical waveguide element are each about 0.3 mm or more and about 1.0 mm or less.
[0055]
In one embodiment, markings for adjusting the alignment between the light emitting portion and the optical waveguide are formed on the array type semiconductor laser chip and the planar optical waveguide element, respectively.
[0056]
In one embodiment, a metal film or a dielectric film for forming a predetermined gap is formed between the array-type semiconductor laser chip and the planar optical waveguide device.
[0057]
The method for manufacturing an optical integrated device of the present invention includes a first mounting step of mounting an array type semiconductor laser chip having two or more light emitting parts on a submount, and two or more optical waveguides, A second mounting step of mounting a planar optical waveguide element in which the distance between the optical waveguides is equal to the distance between the light-emitting portions at a predetermined position on the submount; A cutting step in which the individual pieces have at least one pair of the light emitting portion of the array-type semiconductor laser chip and the optical waveguide of the planar optical waveguide element. The above-mentioned object is achieved.
[0058]
In one embodiment, the second mounting step includes a step of emitting laser light from at least one of the light-emitting portions of the array-type semiconductor laser chip, and the step of emitting the emitted laser light to the planar optical waveguide element. Coupling the optical waveguide to a corresponding one of the optical waveguides, and adjusting the position of the planar optical waveguide element on the submount so that the optical coupling efficiency to the coupled optical waveguide is maximized. And fixing the planar optical waveguide element at the adjusted position on the submount.
[0059]
In one embodiment, the array-type semiconductor laser chip is fixed to the submount such that the surface on the active layer side faces the submount.
[0060]
In one embodiment, the planar optical waveguide device is a wavelength conversion device that converts laser light emitted from the array semiconductor laser chip into light having a half wavelength.
[0061]
In one embodiment, the array type semiconductor laser chip is a distributed Bragg reflection type semiconductor laser chip having an active layer region and a distributed Bragg reflection region.
[0062]
In one embodiment, the array-type semiconductor laser chip oscillates with TE-mode polarized light, and the optical waveguide of the planar optical waveguide element propagates TE-mode light.
[0063]
In one embodiment, the planar optical waveguide device has an optical waveguide formed on a surface of a dielectric substrate or a ferroelectric substrate.
[0064]
In one embodiment, a distance between the light emitting portions of the array-type semiconductor laser chip and a distance between the optical waveguides of the planar optical waveguide element are each about 0.3 mm or more and about 1.0 mm or less.
[0065]
In one embodiment, markings for adjusting the alignment between the light emitting portion and the optical waveguide are formed on the array type semiconductor laser chip and the planar optical waveguide element, respectively.
[0066]
In one embodiment, a metal film or a dielectric film for forming a predetermined gap is formed between the array-type semiconductor laser chip and the planar optical waveguide device.
[0067]
BEST MODE FOR CARRYING OUT THE INVENTION
One aspect of the present invention is to provide an optical waveguide device integrated light source using a DBR semiconductor laser as a wavelength tunable semiconductor laser, to operate the semiconductor laser with high output and high reliability, and to stabilize the operating characteristics of the wavelength tunable semiconductor laser. Has to do with it. Particularly, in a short wavelength light source composed of a DBR semiconductor laser that is a wavelength tunable semiconductor laser and an optical waveguide type wavelength conversion device that is an optical waveguide device, an ultra-small direct coupling type module in which a DBR semiconductor laser is mounted at a junction down is used. To be realized, the present invention is essential.
[0068]
Here, the reason why the DBR semiconductor laser is mounted junction-down is as follows.
(1) The height from the submount to the active layer (junction part) can be controlled with high precision, and when directly coupled to the optical waveguide device, the alignment of the active layer and the optical waveguide in the height direction can be easily adjusted. Can do, and,
(2) Since the heat radiation property of the active layer region is high, it is advantageous for extending the life of the laser and increasing the output.
And the like.
[0069]
In general, the method of varying the oscillation wavelength of a wavelength-tunable semiconductor laser includes (1) use of a change in the refractive index due to carrier injection (use of a plasma effect in which the refractive index is reduced by carrier injection) or (2) high use. Use of a change in the refractive index due to a temperature change caused by current injection into the resistance layer (use of a heater effect in which the refractive index is increased by current injection). In the case of a long-wavelength semiconductor laser such as an InP-based semiconductor laser, the effect of the plasma effect of (1) is greater, whereas in the case of an AlGaAs-based semiconductor laser, the effect of the heater effect of (2) is greater.
[0070]
In the short-wavelength light source described as the prior art, light emitted from an AlGaAs-based wavelength-variable semiconductor laser is used as a fundamental wave, so that the wavelength can be varied using the heater effect. Therefore, when the junction mount is mounted on the submount, the heat dissipation becomes excessively good, and it is difficult to stably realize the variable wavelength, and the power consumption increases. In particular, in the optical waveguide type wavelength conversion device used in the short wavelength light source having the configuration described as the prior art, the allowable width of the phase matching wavelength is as small as about 0.1 nm, and the wavelength control (selectivity) is realized with higher accuracy. Need to be done.
[0071]
In the following, some implementations of a wavelength-tunable semiconductor laser mounting structure of the present invention and a short-wavelength light source using the same are described as a method capable of achieving stable wavelength-tuning operation even when the wavelength-tunable semiconductor laser is mounted in a junction-down manner. The mode will be described with reference to the accompanying drawings.
[0072]
(1st Embodiment)
In the present embodiment, a configuration in which a DBR semiconductor laser 1 having a DBR region 3 and an active layer region 2 is mounted on a submount 5 will be described. More specifically, in the perspective views and cross-sectional views of FIGS. 3A and 3B, the DBR semiconductor laser 1 is mounted on the submount 5 in a junction-down manner, and only the active layer region 2 is mounted on the submount 5. The configuration of the device fixed on the mount 5 is schematically shown.
[0073]
Reference numeral 1 denotes a 100 mW-class AlGaAs-based DBR semiconductor laser oscillating in the TE mode at a wavelength of 850 nm. Electrodes (upper electrode 15a and lower electrode 15b) are formed on the substrate side surface and the active layer surface side of the DBR semiconductor laser 1, respectively. Of these, the lower electrode 15b formed on the active layer side surface is The active layer region 2 is separated from the DBR region 3. The thickness of an epitaxial layer such as an active layer and the thickness of an electrode are controlled to submicron or less, and the thickness up to the active layer (junction part 4) is about 3 μm.
[0074]
Reference numeral 5 denotes a Si submount on which an electrode 13 having a controlled thickness and an Au / Sn layer 14 as a solder layer 14 are deposited. In the present embodiment, the length of the submount 5 is designed to be slightly shorter than the length of the active layer region 2, and only the active layer region 2 is fixed on the submount 5.
[0075]
A wire 12 for electrical connection is connected to each electrode. Of these, the lower electrode 15b in the active layer region 2 is directly connected to the lower electrode 15b because it is fixed to the Si submount 5. Instead, the wire 12 is connected to the electrode 13 on the Si submount 5. On the other hand, a wire 12 is connected to the upper electrode 15a and the lower electrode 15b in the DBR region 3 as shown.
[0076]
In the configurations of FIGS. 3A and 3B, the oscillation threshold current is about 20 mA, which is about 5 mA lower than the conventional one. Further, the driving current at the time of output of about 100 mW is also about 140 mA, which is about 30 mA lower than that of the related art. Therefore, the life of the laser is extended and the reliability is improved.
[0077]
Further, since the DBR region 3 is not in contact with the submount 5, its heat radiation state is worse than that of the active layer region 2. Therefore, in the wavelength tunable characteristic of the DBR semiconductor laser 1 having the configuration of FIGS. 3A and 3B, a wavelength tunable region of about 2 nm can be obtained for an injection current of about 80 mA, as in the case of junction-up mounting. .
[0078]
As described above, when the DBR semiconductor laser 1 is mounted in a junction-down manner as in the present embodiment, that is, only the active layer region 2 is fixed to the submount 5 and the DBR region 3 is not fixed. Wavelength tunable characteristics and highly reliable laser drive characteristics can be obtained, and the practical effect is great.
[0079]
(Second embodiment)
4A and 4B, the DBR semiconductor laser 1 as the wavelength tunable semiconductor laser and the optical waveguide type wavelength conversion device 11 as the optical waveguide device are shown on the submount 6. 1 schematically shows the configuration of the ultra-compact short wavelength light source mounted on the optical system. Specifically, the optical waveguide device 11 used in the present embodiment is an x-cut MgO-doped LiNbO₃This is an optical waveguide type wavelength conversion device 11 in which a proton exchange optical waveguide 126 and a periodically poled region 127 are formed on a substrate 125.
[0080]
On the surface of the Si submount 6, SiO is formed by oxidation as an insulating layer.₂The layer 7 is formed. Thereafter, an adjustment cross key (not shown) and a resist pattern of the electrode 8 are formed again by a photo process, and an Au film is deposited according to the pattern. Further, an Au / Sn layer 9 as a solder layer 9 is deposited on the electrode 8. A groove 10 is formed on the Si submount 6, and the length of the DBR semiconductor laser 1 is adjusted so that only the active layer region 2 is fixed to the submount 6.
[0081]
In mounting the configurations shown in FIGS. 4A and 4B, first, the DBR semiconductor laser 1 is fixed on the Si submount 6. Specifically, an adjustment cross key (not shown) is formed on the DBR semiconductor laser 1 and the Si submount 6, and these cross keys are image-recognized by different cameras, and the respective center lines are set. The DBR semiconductor laser 1 is detected and moved to a position where the center lines coincide with each other by a precision stage. The DBR semiconductor laser 1 is fixed to a tool by vacuum vacuum, while the Si submount 6 is fixed to a table equipped with a pulse heater. Next, the emission end face of the DBR semiconductor laser 1 is image-recognized, and the positioning is adjusted so as to slightly project into the groove 10 above the Si submount 6. When the fixing position is determined, the Si submount 6 is pulse-heated, the Au / Sn layer 9 is melted, and the DBR semiconductor laser 1 is fixed. Thereby, in the DBR semiconductor laser 1, only the active layer region 2 is fixed on the Si submount 6 by junction down.
[0082]
Next, the optical waveguide type wavelength conversion device 11 is fixed on the Si submount 6. Since the optical waveguide 126 formed on the x-cut substrate 125 can guide only TE mode light, planar type direct coupling is possible. On the surface of the optical waveguide type wavelength conversion device 11, a protective film 16 is formed for positioning adjustment in the thickness direction (y direction). The protective film 16 is made of, for example, SiO₂And its thickness is precisely controlled.
[0083]
For fixing the optical waveguide type wavelength conversion device 11, for example, an ultraviolet curing agent is used. Like the semiconductor laser chip 1, a cross key (not shown) is formed on the Si submount 6 and the optical waveguide type wavelength conversion device 11. The center line of the cross key on the optical waveguide type wavelength conversion device 11 coincides with the center line of the cross key on the Si submount 6, and the emission surface of the semiconductor laser chip 1 and the optical waveguide type wavelength conversion device 11 The optical waveguide type wavelength conversion device 11 is moved so that the distance from the incident surface becomes about 3 μm. After that, while applying a certain amount of pressure to the optical waveguide type wavelength conversion device 11, ultraviolet light is irradiated and fixed.
[0084]
Next, wires 12 for electrical connection are connected to the respective electrodes. Among them, the lower electrode 15b in the active layer region 2 of the DBR semiconductor laser 1 is fixed to the Si submount 6, so that the wire 12 is not directly connected to the lower electrode 15b. The wire 12 is connected to 8. On the other hand, a wire 12 is connected to the upper electrode 15a and the lower electrode 15b in the DBR region 3 as shown.
[0085]
In this embodiment, since the DBR semiconductor laser 1 is fixed by junction-down mounting, a laser output of about 100 mW can be obtained for an operating current of about 140 mA. Also, since the height of the active layer 4 and the height of the optical waveguide 126 are precisely controlled, a laser beam of about 60 mW can be coupled to the optical waveguide 126. Further, since the DBR region 3 is not in contact with the submount 6, the heat radiation state thereof is worse than that of the active layer region 2, and a stable tunable characteristic can be obtained.
[0086]
The oscillation wavelength is varied by changing the current injected into the DBR region 3 of the DBR semiconductor laser 1, and the oscillation wavelength of the semiconductor laser 1 is made to coincide with the phase matching wavelength of 851 nm of the optical waveguide type wavelength conversion device 11 so that the wavelength 425. 5 nm blue light is obtained at an output of about 10 mW.
[0087]
Further, in this embodiment, the Si submount 6 on which the DBR semiconductor laser 1 and the optical waveguide type wavelength conversion device 11 are mounted is₂Enclose with. Thus N₂(0.066 calcm)^-1・ Sec^-1・ Deg^-1), It is possible to prevent the heat dissipation of the DBR region 3 and at the same time to prevent the laser end face from being deteriorated. Also, N₂Gas having even lower thermal conductivity than Kr (0.021 cal · cm^-1・ Sec^-1・ Deg^-1) Or a vacuum state can reduce the heat radiation, so that the injection current for tunable wavelength can be reduced.
[0088]
(Third embodiment)
Also in the present embodiment, the DBR semiconductor laser 1 having the DBR region 3 is used as the wavelength tunable semiconductor laser 1 as in the first embodiment. 5A and 5B, the DBR semiconductor laser 1 is mounted on the Si submount 20 by junction down, and a part of the DBR region 3 and the active layer region 2 are submount. The device configuration fixed on top of 20 is shown schematically.
[0089]
In the device configuration of the present embodiment, unlike the device configuration of the first embodiment, a groove 21 is formed on the Si submount 20. This groove 21 is formed by a photolithography process and a dry etching process. The width of the groove 21 is smaller than the width of the DBR semiconductor laser 1, and a part of the DBR region 3 is also fixed on the Si submount 20.
[0090]
On the surface of the Si submount 20, as an insulating layer, SiO₂A layer 22 is formed. An Au layer 23 as an electrode 23 and an Au / Sn layer 24 as a fixing solder layer 24 are sequentially deposited thereon. The electrode 23 and the solder layer 24 in the active layer region 2 are electrically separated from the electrode 23 and the solder layer 24 in the DBR region 3. Further, the electrode 15b on the active layer 4 of the DBR semiconductor laser 1 is also electrically separated between the active layer region 2 and the DBR region 3. The DBR semiconductor laser 1 is fixed on the submount 20 by junction down so that the separated portion of the electrode 23 and the solder layer 24 coincides with the separated portion of the electrode 15b. In this mounting, the entire surface of the active layer region 2 is fixed by contacting the submount 20, while the DBR region 3 is fixed by contacting a part of the surface thereof to the submount 20.
[0091]
Next, wires 25 for electrical connection are connected to the respective electrodes. Of these, the lower electrode 15b of the DBR semiconductor laser 1 is fixed to the Si submount 20 in both the active layer region 2 and the DBR region 3, so that the wire 25 is not directly connected. A wire 25 is connected to the electrode 23 on the submount 20. On the other hand, a wire 25 is connected to the upper electrode 15a as shown. In this case, since the wire 25 is connected to any of the electrodes from above, the formation is easy.
[0092]
In the device configuration of the present embodiment formed as described above, the oscillation threshold current is about 20 mA. The driving current at an output of about 100 mW is about 140 mA. Further, since the DBR region 3 contacts only a part of the submount 20, the heat radiation state thereof is worse than that of the active layer region 2. Therefore, the wavelength tunable characteristic is almost the same as that of the junction-up mounting. A wavelength tunable region of about 2 nm is obtained for an injection current of 90 mA.
[0093]
As in the present embodiment, when the DBR semiconductor laser 1 is mounted junction-down, the active layer region 2 is entirely fixed to the submount 20, and only a part of the DBR region 3 is fixed to the submount 20. Thereby, stable wavelength tunable characteristics and laser drive characteristics with high reliability can be obtained, and the practical effect is large. Further, in the configuration of the present embodiment, compared to the configuration of the first embodiment, the heat distribution (radiation distribution) in the DBR region 3 is small, so that a more stable wavelength tunable characteristic in the single longitudinal mode is obtained. Can be
[0094]
(Fourth embodiment)
6A and 6B, the DBR semiconductor laser 1 as a wavelength tunable semiconductor laser and the optical waveguide type wavelength conversion device 11 as an optical waveguide device are shown on the submount 26. 1 schematically shows the configuration of the ultra-compact short wavelength light source mounted on the optical system. Specifically, the optical waveguide device 11 used in the present embodiment is an x-cut MgO-doped LiNbO₃This is an optical waveguide type wavelength conversion device 11 in which a proton exchange optical waveguide 126 and a periodically poled region 127 are formed on a substrate 125.
[0095]
In the device configuration of the present embodiment, unlike the device configuration of the second embodiment, a groove 27 is formed on a Si submount 26. This groove 27 is formed by a photolithography process and a dry etching process. The width of the groove 27 is smaller than the width of the DBR semiconductor laser 1, and a part of the DBR region 3 is also fixed on the Si submount 26.
[0096]
Further, similarly to the configuration of the third embodiment, the surface of the submount 26 is₂A layer 28, an electrode 29, and a solder layer (Au / Sn layer) 30 are formed, and these are electrically separated by the active layer region 2 and the DBR region 3.
[0097]
6A and 6B are implemented by the same method as in the second embodiment. That is, first, the DBR semiconductor laser 1 is fixed on the Si submount 26. More specifically, an adjustment cross key (not shown) is formed on the DBR semiconductor laser 1 and the Si submount 26, and these cross keys are image-recognized by separate cameras, and the respective center lines are set. The DBR semiconductor laser 1 is detected and moved to a position where the center lines coincide with each other by a precision stage. The emission end face of the DBR semiconductor laser 1 is image-recognized, and the positioning is adjusted so as to slightly project into the groove 31 on the Si submount 26. When the fixing position is determined, the Si submount 26 is pulse-heated, the Au / Sn layer 30 is melted, and the DBR semiconductor laser 1 is fixed. Thus, the DBR semiconductor laser 1 is fixed on the Si submount 26 at the junction down. Subsequently, the optical waveguide type wavelength conversion device 11 is fixed on the Si submount 26 in the same manner as in the second embodiment.
[0098]
In the configuration of the present embodiment obtained as described above, the oscillation threshold current of the DBR semiconductor laser 1 is about 20 mA. The driving current at an output of about 100 mW is about 140 mA. Further, when the injection current into the DBR region 3 is about 90 mA, a wavelength tunable region of about 2 nm can be obtained. Also, since the height of the active layer 4 and the height of the optical waveguide 126 are precisely controlled, a laser beam of about 60 mW can be coupled to the optical waveguide 126.
[0099]
The oscillation wavelength is varied by changing the current injected into the DBR region 3 of the DBR semiconductor laser 1, and the oscillation wavelength of the semiconductor laser 1 is made to coincide with the phase matching wavelength of 851 nm of the optical waveguide type wavelength conversion device 11 so that the wavelength 425. 5 nm blue light is obtained at an output of about 10 mW. Further, in the configuration of the present embodiment, since the heat distribution (radiation distribution) in the DBR region 3 is smaller than in the configuration of the second embodiment, more stable single longitudinal mode oscillation can be realized, and the output of blue light is stabilized. Performance can also be improved.
[0100]
(Fifth embodiment)
In the present embodiment, the submount 35 is composed of a combination of two portions 35A and 35B made of materials having different thermal conductivities, so that the heat radiation state in the active layer region 2 and the DBR region 3 of the DBR semiconductor laser 1 is improved. A description will be given of a configuration in which a difference is generated between the two to realize more stable laser oscillation and wavelength tunable characteristics.
[0101]
In the case where the submount 35 is formed by combining materials having different thermal conductivities, if a ceramic material is selected, it can be easily formed with good workability. For example, as a ceramic material having good thermal conductivity, AlN (thermal conductivity: 0.4 cal · cm)^-1・ Sec^{− 1}・ Deg^-1) Or SiC (thermal conductivity: 0.15 calcm)^-1・ Sec^-1・ Deg^-1) Is Si (thermal conductivity: 0.3 cal · cm)^-1・ Sec^-1・ Deg^-1)), And ceramic materials having poor thermal conductivity include ZrO.₂(Thermal conductivity: 0.01 cal · cm^-1・ Sec^-1・ Deg^-1).
[0102]
7A and 7B show the DBR semiconductor laser 1 with AlN and ZrO.₂1 schematically shows a configuration of a wavelength tunable semiconductor laser mounted on a submount 35 composed of a laser diode.
[0103]
The submount 35 includes a portion 35A to which the active layer region 2 of the DBR semiconductor laser 1 is fixed and a portion 35B to which the DBR region 3 is fixed. The material of the portion 35A is AlN. The material is ZrO₂It is. Further, on the submount 35, an electrode 36 and a solder layer 37 are formed in the same manner as in the configuration of the previous embodiments, and the portions 35A and 35B are electrically separated from each other. Further, the lower electrode 15b located on the side of the active layer 4 of the DBR semiconductor laser 1 is also divided into two electrically separated parts, and the two parts of the separated lower electrode 15b are connected to the submount 35. The DBR semiconductor laser 1 is fixed on the submount 35 by junction down so as to correspond to the two portions 35A and 35B, respectively. After the bonding of the DBR semiconductor laser 1, a wire 38 is formed from each electrode as shown.
[0104]
Since the portion 35A of the submount 35 is made of AlN, heat generated in the active layer region 2 of the DBR semiconductor laser 1 is efficiently radiated to the submount 35. On the other hand, the portion 35B is made of ZrO₂, The heat conduction from the DBR region 3 to the submount 35 is reduced.
[0105]
In the present embodiment, AlN having a higher thermal conductivity than Si used in the first to fourth embodiments is used as a constituent material of the submount 35. The oscillation threshold current of the DBR semiconductor laser 1 is about 20 mA, and the driving current when the output is about 100 mW is about 130 mA. On the other hand, the heat radiation state of the DBR region 3 is ZrO₂, A wavelength tunable region of about 2 nm can be obtained for an injection current of about 100 mA.
[0106]
As in the present embodiment, in the submount 35 on which the DBR semiconductor laser 1 is mounted, a component 35A having a high thermal conductivity is used for a portion 35A corresponding to the active layer region 2 and a portion corresponding to the DBR region 3 is used for the portion 35A. By using a material having low thermal conductivity, highly reliable laser drive characteristics and stable wavelength tunable characteristics can be obtained.
[0107]
In the above description, the DBR region 3 is entirely fixed to the portion 35B of the submount 35. However, similarly to the third embodiment, a groove having an appropriate pattern is formed in ZrO.₂By forming the portion 35B made of, the thermal conductivity can be further intentionally reduced, and more stable wavelength variable characteristics can be obtained.
[0108]
(Sixth embodiment)
8A and 8B, the DBR semiconductor laser 1 as a wavelength tunable semiconductor laser and the optical waveguide type wavelength conversion device 11 as an optical waveguide device are shown on the submount 39. 1 schematically shows the configuration of the ultra-compact short wavelength light source mounted on the optical system. Specifically, the optical waveguide device 11 used in the present embodiment is an x-cut MgO-doped LiNbO₃This is an optical waveguide type wavelength conversion device 11 in which a proton exchange optical waveguide 126 and a periodically poled region 127 are formed on a substrate 125.
[0109]
Here, the submount 39 is composed of the following three parts;
Portion 39A: Portion where optical waveguide type wavelength conversion device is fixed
Portion 39B: portion where active layer region is fixed
Part 39C: Part where DBR area is fixed
Portions 39A and 39C are ZrO₂The portion 39B is made of AlN ceramics, while the portion 39B is made of ceramics. An electrode 40 and a solder layer 41 are formed on the surface of the submount 39 where the DBR semiconductor laser 1 is fixed, as in the previous embodiments. A groove 42 is formed between the place where the DBR semiconductor laser 1 is fixed and the place where the optical waveguide type wavelength conversion device 11 is fixed.
[0110]
As in the fourth embodiment, the DBR semiconductor laser 1 and the optical waveguide type wavelength conversion device 11 were fixed on a submount 39, wires 38 were formed from the respective electrodes, and the operating characteristics of the DBR semiconductor laser 1 were measured. The oscillation threshold current was about 20 mA, and the driving current at an output of about 100 mW was about 130 mA. When the amount of current injected into the DBR region 3 was about 100 mA, a wavelength tunable region of about 2 nm was obtained.
[0111]
Since the phase matching wavelength of the optical waveguide type wavelength conversion device 11 has a temperature dependency, when a temperature distribution occurs inside the optical waveguide type wavelength conversion device 11 due to heat from the active layer 4 of the DBR semiconductor laser 1, Affects wavelength conversion efficiency and operation stability. Therefore, in the configuration of the second or fourth embodiment described above, for a laser output of about 100 mW, only an output of about 10 mW can be obtained from the wavelength conversion device. On the other hand, in the configuration of the present embodiment, the heat generated in the active layer region 2 of the DBR semiconductor laser 1 is efficiently radiated to the portion 39B of the submount 39 made of AlN ceramics, and Since the formation of the groove 42 can prevent heat transfer to the optical waveguide type wavelength conversion device 11, the reliability of the DBR semiconductor laser 1 and the uniformity of the optical waveguide type wavelength conversion device 11 can be improved. As a result, a blue output of about 15 mW can be obtained from the wavelength conversion device 11 for a laser output of about 100 mW.
[0112]
(Seventh embodiment)
In the first to sixth embodiments, the wavelength tunable semiconductor laser and the short wavelength light source using the DBR semiconductor laser 1 including the active layer region 2 and the DBR region 3 have been described. A configuration using a DBR semiconductor laser to which a compensation region is added will be described. The above configuration is schematically shown in the perspective view and the plan view of FIGS.
[0113]
The DBR semiconductor laser 45 included in this configuration is a 100 mW-class AlGaAs-based distributed Bragg reflection (DBR) semiconductor laser 45 that oscillates in TE mode at a wavelength of 850 nm, and includes an active layer region 46, a phase compensation region 47, and a DBR region 48. Be composed. Electrodes 15a and 15b are formed on the substrate side and the active layer side of the DBR semiconductor laser 45, respectively. In particular, the lower electrode 15b on the active layer side includes an active layer region 46, a phase compensation region 47, and a DBR region 48. Is electrically isolated by The thicknesses of the epitaxial layers such as the active layer 4 and the electrodes 15a and 15b are controlled to submicron or less, and the thickness up to the active layer (junction 4) is about 3 μm.
[0114]
On the other hand, the submount 49 is made of Si, and has a groove 50 formed therein. The length of the groove 50 substantially matches the combined length of the phase compensation region 47 and the DBR region 48 of the DBR semiconductor laser 45. Thus, while the heat generated in the active layer region 46 is radiated to the Si submount 49, the heat generated by the injected current is hard to radiate in the phase compensation region 47 and the DBR region 48.
[0115]
On the Si submount 49, the electrode 51 and the solder layer 52 whose film thickness is controlled are deposited as in the above embodiments. The electrode 51 and the solder layer 52 are electrically separated from each other at portions where the active layer region 46, the phase compensation region 47, and the DBR region 48 are fixed. The length of the electrode 51 at the portion where the phase compensation region 47 is fixed is the same as the length of the phase compensation region 47.
[0116]
As in the previous embodiments, the DBR semiconductor laser 45 was fixed on the submount 49, wires 38 were formed from the respective electrodes, and the operating characteristics of the DBR semiconductor laser 45 were measured. The drive current is about 20 mA when the output is about 100 mW. In addition, the wavelength tunable characteristic of about 2 nm can be continuously obtained by performing phase adjustment by the phase compensation region 47 with respect to the injection current amount of about 90 mA in almost the same manner as in the junction up.
[0117]
Even when the DBR semiconductor laser 45 to which the phase compensation region 47 is added is mounted junction-down as in the present embodiment, stable wavelength tunable characteristics and highly reliable laser drive characteristics can be obtained. The effect is great.
[0118]
Further, in the above description of the present embodiment, the configuration in which the DBR semiconductor laser 45 is mounted on the Si submount 49 in which the groove 50 is formed is described, but as described in the fifth or sixth embodiment. The same effect can be obtained by a configuration in which a plurality of parts made of different materials (ceramics) are mounted on a submount in which the parts are combined.
[0119]
In the first to seventh embodiments described above, the optical waveguide type wavelength conversion device is used as the optical waveguide device.₃The same effect can be obtained by using an optical waveguide type functional device such as an optical waveguide type high-speed modulation device formed on a substrate. Further, when a DBR semiconductor laser is used as a light source for an absolute reference wavelength or a light source for wavelength division multiplexing in the field of optical communication, when a laser beam is coupled to an optical fiber fixed to a V-groove formed in a submount, By fixing the DBR semiconductor laser in the configuration as in the first to fourth embodiments, it is possible to obtain highly reliable laser drive characteristics and stable wavelength tunable characteristics.
[0120]
Furthermore, although the configuration of the direct coupling type module has been described above, even if the present invention is applied to a lens coupling type module, the practical effect is large, and by mounting the DBR semiconductor laser on the submount in a junction down, High reliability is obtained even in a high output oscillation state. For example, taking the configuration of the first embodiment as an example, the drive current value at an output of about 100 mW is reduced by about 30 mA.
[0121]
In order to stably drive a high-power semiconductor laser, it is necessary to improve the heat radiation state of the semiconductor laser chip. In a short-wavelength light source composed of a semiconductor laser and a wavelength-variable device, a high-output semiconductor laser is particularly used because the obtained harmonic output is proportional to the square of the semiconductor laser output. Therefore, junction-down mounting is particularly needed.
[0122]
In addition, when an optical integrated device composed of a semiconductor laser and an optical waveguide device is applied to consumer applications, size and cost are significant factors, and junction down mounting technology is also necessary to realize that. It becomes. This is because the height from the submount to the active layer (junction part) can be controlled with high precision in the junction-down mounting, so that when the optical waveguide device is directly coupled to the semiconductor laser, the height between the active layer and the optical waveguide is high. This is because alignment adjustment in the vertical direction is easily realized.
[0123]
As described above, according to the first to seventh embodiments of the present invention, a DBR semiconductor laser as a wavelength tunable semiconductor laser and an optical element such as an optical waveguide type wavelength conversion device or an optical fiber as an optical waveguide type device In the optical waveguide integrated light source fixed to the submount, the DBR semiconductor laser is fixed on the submount with high accuracy by junction down to improve the heat radiation of the active layer region of the DBR semiconductor laser while improving the heat dissipation of the DBR region. By intentionally reducing the heat radiation, stable oscillation characteristics and tunable wavelength characteristics are realized, and a module light source that enables more efficient optical coupling is provided. That is, the present invention realizes stable wavelength tunable characteristics and highly reliable laser oscillation characteristics when a short wavelength light source or a DBR semiconductor laser which is indispensable in the field of optical communication is mounted in a junction-down manner as described above. The practical effect is great.
[0124]
On the other hand, in the present invention described below as the eighth and subsequent embodiments, a configuration is disclosed which is intended to improve mass productivity when a semiconductor laser chip is mounted on a submount.
[0125]
Here, examples of the semiconductor laser chip that can be used include a DBR semiconductor laser including an active layer region and a DBR region, a distributed feedback (DFB) InP semiconductor laser, and the like. On the other hand, examples of the optical waveguide element include a wavelength conversion device that converts laser light emitted from an optical fiber or a semiconductor laser chip into light having a half wavelength of the oscillation wavelength. Furthermore, Au / Sn or Pb / Sn is used as solder, an adhesive containing an ultraviolet curing agent (hereinafter referred to as an ultraviolet curing adhesive) is used as an adhesive, and Van der Waals force is used as a molecular bonding force. , Respectively.
[0126]
(Eighth embodiment)
In the configuration of the optical integrated device of the present embodiment schematically shown in FIG. 10, a groove 103 is formed on the surface of the submount 101 where the semiconductor laser chip 106 is fixed, and solder is provided inside the groove 103. ing. The semiconductor laser chip 106 is fixed in close contact with the submount 101 using solder supplied into the groove 103.
[0127]
The submount 101 made of silicon (Si) has an insulating layer formed of SiO 2 on its surface.₂It has a layer 102. Submount 101 SiO₂The groove 103 of the present invention is formed on the layer 102. The semiconductor laser chip 106 is made of SiO₂Mounted on layer 102. In the present embodiment, a 1.55 μm band distributed feedback (DFB) InP semiconductor laser is used as the semiconductor laser chip 106. Further, cross keys 107 and 108 for image recognition are formed on the surfaces of the submount 101 and the semiconductor laser chip 106. Further, an optical fiber 110 as an optical waveguide element is mounted in a V-groove 109 formed on the submount 101, and laser light from the semiconductor laser chip 106 is coupled to the optical fiber 110.
[0128]
FIG. 11 is a cross-sectional view along the line XI-XI of FIG. 10 including the center line A1 between the cross keys 107, and shows a state where the semiconductor laser chip 106 and the optical fiber 110 are mounted on the submount 101.
[0129]
As shown, the SiO 2₂An Au layer 104 is formed as an electrode in a groove 103 formed on the layer 102, and a solder 105 is provided inside the groove 103. In the present embodiment, the solder 105 is made of Au / Sn.
[0130]
In the related art, an Au layer is generally formed on a submount as an electrode, and Au / Sn is deposited thereon as a solder layer. The thickness of the solder layer is about 2 μm to about 3 μm. The semiconductor laser chip is arranged so that its junction (active layer portion) is on the submount side, and is fixed on the submount by heating the submount and melting the solder.
[0131]
The thickness from the surface of the semiconductor laser chip to the active layer is precisely controlled during epitaxial growth. Further, the thickness of the Au layer on the submount is also accurately controlled. Therefore, the height of the active layer from the submount greatly depends on the thickness controllability of the solder layer. However, in practice, the controllability is only about ± 1 μm in order to fix the semiconductor laser chip by melting the solder layer. As a result, variations occur in the height of the light emitting point of the semiconductor laser chip from the submount, and it is difficult to fix the semiconductor laser on the submount with high accuracy in the related art.
[0132]
On the other hand, in the configuration of the present embodiment, as shown in FIG. 11, the groove 103 is formed on the surface of the submount 101, and the solder 105 exists inside the groove 103. The surface and the Au layer 104 of the submount 101 are in direct contact. Therefore, the height from the submount 101 to the active layer of the semiconductor laser chip 106 depends only on the accuracy of the thickness of the Au layer 104, and as a result, the positioning in the height direction is performed with high accuracy.
[0133]
Next, a method for forming the submount 101 in the present embodiment will be described.
[0134]
First, as an insulating layer, SiO.sub.2 is formed on the surface of a submount 101 composed of a Si (100) substrate by oxidation.₂A layer 102 is formed.
[0135]
Next, a resist is applied on the submount 101, and a periodic resist pattern having a width of about 10 μm and a period of about 20 μm, and a V-groove resist pattern having a width of about 100 μm are formed by a photo process. After forming them, a groove 103 having a depth of about 5 μm is formed on the submount 101 by wet etching. Since the (111) plane appears in the wet etching of the (100) substrate surface, a trapezoidal (V-groove portion is triangular) groove is formed. Alternatively, it is also possible to form a rectangular groove by performing dry etching.
[0136]
Next, after removing the resist, the cross key 107 for adjustment and the resist pattern of the electrode are formed again by a photo process, and the Au layer 104 is deposited. Next, in order to vapor-deposit solder (Au / Sn) only in the inside of the groove 103, the resist is removed again, and the position of the mask is adjusted using the same mask as that used when the groove 103 is formed. A resist pattern similar to that at the time of formation is formed, and solder (Au / Sn) is deposited using the same resist pattern. Thereby, the solder 105 can be formed inside the groove 103.
[0137]
On the other hand, a cross key 108 is also formed on the surface of the semiconductor laser chip 106. The cross key 107 on the surface of the submount 101 is formed at a position symmetrical with respect to the center line A1 of the V groove 109, and the cross key 108 on the surface of the semiconductor laser chip 106 is It is formed at a position symmetrical with respect to (on the center line B1).
[0138]
In the present embodiment, the width of the groove 103 formed in the submount 101 and the interval (distance between the adjacent grooves 103) are both set equal to 10 μm. However, considering the heat radiation of the semiconductor laser chip 106, the larger the area of the groove 103 (or the solder (Au / Sn) 105 formed therein), the larger the heat radiation effect to the submount 101. This is advantageous in improving the life (reliability) of the semiconductor laser chip 106.
[0139]
Next, an alignment adjustment method in the configuration of the present embodiment will be described with reference to FIG.
[0140]
As shown in FIG. 12, the semiconductor laser chip 106 is fixed by junction down so that the surface on which the active layer is formed (epitaxial growth surface) is located on the submount side. In the present embodiment, the cross keys 108 and 107 formed on the semiconductor laser chip 106 and the submount 101 are image-recognized by separate cameras 111 and 112, and their center lines A1 and B1 are detected. The semiconductor laser chip 106 is moved to a position where the line coincides with the precision stage and mounted.
[0141]
The semiconductor laser chip 106 is fixed to a tool 113 by vacuum vacuum, and the submount 101 is fixed to a base 114 equipped with a pulse heater. An image of the cross key 108 formed on the semiconductor laser chip 106 is recognized by the camera 111, and an image of the cross key 107 on the submount 101 is recognized by the camera 112. Thus, the center line A1 between the cross keys 107 and the center line between the cross keys 108 are detected. Thereafter, the semiconductor laser chip 106 is moved by the precision stage so that the center lines A1 and B1 coincide.
[0142]
Next, the emission end face of the semiconductor laser chip 106 is image-recognized by the camera 112, and the electrode is adjusted so as to match the pattern of the cross key 107 on the submount 101. When the fixing position is determined, the submount 101 is pulse-heated to melt the solder 105 and fix the semiconductor laser chip 106. Thereby, the semiconductor laser chip 106 is mounted in close contact with the Au layer 104 of the submount 101 as shown in FIG.
[0143]
If the volume of the solder 105 after fixing is smaller than the volume of the groove 103, the adhesion at the time of mounting is increased, and the practical effect is large.
[0144]
After fixing the semiconductor laser chip 106, as shown in FIGS. 10 and 11, an optical fiber 110 is mounted in the V-groove 109 as an optical waveguide element. At this time, the distance between the end face of the optical fiber 110 and the emission end face of the semiconductor laser chip 106 is determined by the distance between the submount 101 and the electrode. In this embodiment, since the height from the submount 101 to the light emitting point of the semiconductor laser 106 is precisely controlled, the coupling efficiency depends on the processing accuracy of the V-groove 109 of the submount 101. Specifically, since the V-groove 109 is precisely processed by etching, a value of about 30% can be stably obtained as the coupling efficiency to the optical fiber 110.
[0145]
In the present embodiment, as shown in FIG. 11, the Au layer 104 on the submount 101 is in close contact with the surface of the semiconductor laser chip 106, so that the height from the submount to the active layer is Au layer 104. It can be mounted with high accuracy depending on the thickness accuracy of the device. However, in practice, no relief groove is provided for the solder (Au / Sn) 105 disposed in the groove 103, so that when the solder 105 is supplied in an excessive amount, the positioning accuracy in the height direction is reduced. Negative effects can occur. Therefore, the supply amount of the solder 105 needs to be equal to or smaller than the volume of the groove 103.
[0146]
On the other hand, FIG. 25 shows a modification of the configuration of FIG. 10, in which a clearance groove 133 is formed adjacent to each groove 103. Therefore, even if the solder 105 is excessively supplied, the excessive amount is pushed out to the escape groove 133 at the time of mounting. For this reason, the adhesion between the semiconductor laser chip 106 and the submount 101 is improved, and an excessive effect on the positioning accuracy in the height direction due to solder is avoided. In FIG. 25, the same components as those in FIG. 10 are denoted by the same reference numerals, and a description thereof will not be repeated.
[0147]
The method for forming the configuration in FIG. 25 is as follows.
[0148]
First, as an insulating layer, a SiO.sub.₂A layer 102 is formed.
[0149]
Next, a resist is applied on the submount 101, and a predetermined resist pattern is simultaneously formed by a photo process. After the formation, the groove 103 and the relief groove 133 having a depth of about 5 μm are simultaneously formed on the submount 101 by wet etching.
[0150]
After the resist is removed, a cross key 107 for adjustment and a resist pattern of an electrode are formed again by a photo process, and the Au layer 104 is deposited. Next, in order to vapor-deposit solder (Au / Sn) only in the inside of the groove 103, the resist is removed again, and the mask is aligned using a mask different from that used when the groove 103 is formed. A resist pattern different from that at the time of forming 103 is formed, and solder (Au / Sn) is vapor-deposited using the resist pattern. At this time, the solder 105 is not deposited on the entire groove 103 but on a region where the semiconductor laser chip 106 is fixed. As a result, clearance grooves 133 are formed on both sides of the solder 105, and the adhesion between the semiconductor laser chip 106 and the submount 101 during mounting is improved.
[0151]
With the above configuration, the sub-micron or less alignment adjustment accuracy required for coupling the laser beam from the semiconductor laser chip 106 to the optical fiber 110 or the optical waveguide with high efficiency can be easily realized. And an optical integrated device having a high density is provided.
[0152]
In the above embodiment, the case where the optical fiber 110 is used as the optical waveguide element is described. However, as the optical waveguide element, the wavelength of the laser light emitted from the semiconductor laser chip 106 is converted into light having a half wavelength. Of course, it is also possible to use a wavelength conversion device. Further, as the semiconductor laser chip 106, a DBR semiconductor laser chip including an active layer region and a DBR region can be used.
[0153]
For example, a 100 mW class distributed Bragg reflection type (DBR) AlGaAs semiconductor laser (oscillation wavelength: 850 nm) oscillating in a TE mode is used as a semiconductor laser chip, and x-cut MgO-doped LiNbO is used as an optical waveguide device.₃It is possible to use an optical waveguide type wavelength conversion device in which a proton exchange optical waveguide and a periodically poled region are formed on a substrate. In such a configuration, the optical waveguide fabricated on the x-cut substrate can guide only the light in the TE mode, so that the planar type direct coupling is realized.
[0154]
In the above description, the groove 103 is formed in a direction perpendicular to the light emitting region of the semiconductor laser chip 106. On the other hand, a configuration using the submount 115 in which the groove 117 is formed in a direction parallel to the light emitting region of the semiconductor laser chip 120 will be described below with reference to FIGS.
[0155]
Also in the configuration of the optical integrated device schematically shown in FIG. 13, the submount 115 made of silicon (Si)₂It has a layer 116. Submount 115 SiO₂A groove 117 is formed on the layer 116. The semiconductor laser chip 120 is made of SiO₂Mounted on layer 116. Cross keys 121 and 122 for image recognition are formed on the surface of the submount 115 and the semiconductor laser chip 120. An optical fiber 124 as an optical waveguide element is mounted in a V-shaped groove 123 formed on the submount 115, and laser light from the semiconductor laser chip 120 is coupled to the optical fiber 124.
[0156]
FIG. 14 is a cross-sectional view along the line XIV-XIV of FIG. 13 including the center line A2 between the cross keys 121, and shows a state where the semiconductor laser chip 120 and the optical fiber 124 are mounted on the submount 115. As shown, the SiO 2₂An Au layer 118 is formed as an electrode in a groove 117 formed on the layer 116, and a solder (Au / Sn) 119 is provided inside the groove 117.
[0157]
At the time of mounting, the cross keys 121 and 122 are image-recognized, the respective center lines A2 and B2 are detected, and the semiconductor laser chip 120 is mounted on the submount 115 so that they match. At this time, as shown in FIG. 10, the direction of the active layer of the semiconductor laser and the direction of forming the groove of the submount are perpendicular to each other, and the portion where the active layer is fixed to the submount via solder is a semiconductor. In a configuration in which the laser beam periodically exists in the optical axis direction, the heat distribution generated during operation may be periodic in the optical axis direction. On the other hand, the configuration shown in FIG. 13 is advantageous because the heat radiation from the semiconductor laser chip 120 is uniformly performed, which leads to an improvement in reliability.
[0158]
(Ninth embodiment)
In the configuration of the optical integrated device of this embodiment schematically shown in FIG. 15, a groove 202 is formed on the surface of the submount 201 where the planar optical waveguide element 204 is fixed in addition to the portion where the semiconductor laser chip 203 is fixed. It is formed and solder is provided inside the groove 202. The planar optical waveguide element 204 and the semiconductor laser chip 203 are fixed to the submount 201 in close contact with the solder provided in these grooves.
[0159]
The optical waveguide of the planar optical waveguide device 204 is an optical waveguide formed on a dielectric substrate or a ferroelectric substrate by an ion exchange method such as proton exchange or a diffusion method such as Ti diffusion. Since it can be manufactured by a semiconductor process, mass productivity is high.
[0160]
In the configuration of FIG. 15, the semiconductor laser chip 203 is mounted on the sub-mount 201 junction-down in the same manner as in the eighth embodiment. The submount 201 is made of, for example, silicon (Si).
[0161]
As the planar optical waveguide element 204, x-cut MgO-doped LiNbO₃An optical waveguide type wavelength conversion device 204 having a proton exchange optical waveguide 209 and a periodically poled region 210 formed on a substrate is used. On the other hand, as the semiconductor laser chip 203, a 100 mW class distributed Bragg reflection type (DBR) AlGaAs semiconductor laser oscillating in the TE mode (oscillation wavelength: 850 nm) is used. Since the optical waveguide manufactured on the x-cut substrate can guide only the light of the TE mode, the above-described configuration enables the planar type direct coupling. On the other hand, when an optical waveguide fabricated on a z-cut substrate is used, a half-wave plate is required to match the polarization directions, and the coupling efficiency is reduced during direct coupling.
[0162]
A protective film 205 is formed on the surface of the optical waveguide type wavelength conversion device 204 for alignment adjustment in the thickness direction (y direction). This protective film 205 is made of, for example, SiO₂It is composed of a sputtering film, and its thickness is precisely controlled.
[0163]
FIG. 16 is a cross-sectional view along the line XVI-XVI of FIG. 15 including the center line A3 between the cross keys 207. The semiconductor laser chip 203 and the optical waveguide type wavelength conversion device 204 are mounted on the submount 201. Indicates the status.
[0164]
As shown in FIG. 16, a fixing adhesive 206 is injected into the groove 202. In the present embodiment, for example, an ultraviolet curable adhesive is used as the adhesive 206. Since the UV-curable adhesive has a low viscosity, it can be easily injected into the groove 202 and has high practicality.
[0165]
In the configuration in which the relief groove is not provided as shown in FIG. 15, it is desirable that the volume after curing of the adhesive 206 be smaller than the volume of the groove 202 in order to enhance the adhesion. Alternatively, as described in the eighth embodiment with reference to FIG. 25, if a clearance groove is provided adjacent to the groove 202, excess adhesive flows into the clearance groove at the time of mounting, so that alignment accuracy is reduced. The adhesion between the planar optical waveguide element 204 and the submount 201 is improved without any adverse effect.
[0166]
As shown in FIG. 15, cross keys 207 and 208 are formed on the submount 201 and the optical waveguide type wavelength conversion device 204 for mounting the wavelength conversion device 204 in the same manner as for mounting the semiconductor laser chip. The center line A3 between the cross keys 207 coincides with the center line B3 between the cross keys for fixing the semiconductor laser chip.
[0167]
At the time of mounting, the center line of the cross key 208 on the optical waveguide type wavelength conversion device 204 coincides with the center line of the cross key 207 on the submount 201, and the emission surface of the semiconductor laser chip 203 is aligned with the optical waveguide type wavelength conversion device. The optical waveguide type wavelength conversion device 204 is moved so that the distance between the device 204 and the incident surface is about 3 μm (see FIG. 16). Thereafter, the adhesive 206 is fixed by irradiating ultraviolet rays while the optical waveguide type wavelength conversion device 204 is constantly pressed.
[0168]
In the module configuration of the present invention, since the adhesive 206 is present inside the groove 202, the protective film 205 and the submount 201 are in close contact with each other, and alignment adjustment in the thickness direction can be performed by the thickness accuracy of the protective film 205. I can do it. Therefore, a coupling efficiency of 70% can be realized with a high yield.
[0169]
Specifically, by changing the current injected into the DBR region of the semiconductor laser chip 203 to vary the oscillation wavelength, and by matching the oscillation wavelength of the semiconductor laser 203 to the phase matching wavelength of the optical waveguide type wavelength conversion device 204, From the wavelength conversion device 204, an output of about 10 mW of blue light having a wavelength of 425 nm is obtained.
[0170]
When the optical waveguide type wavelength conversion device is fixed with an adhesive (ultraviolet curable adhesive) on the submount where the groove 202 does not exist, the thickness of the adhesive layer between the optical waveguide element and the submount Greatly affects the accuracy of the alignment adjustment in the y direction. In addition, the shrinkage phenomenon generally occurring when the adhesive is cured further degrades the accuracy of the alignment adjustment. Due to these factors, according to the related art, it was difficult to fix the optical waveguide wavelength conversion device to the submount with an adjustment accuracy of submicron or less. On the other hand, in the configuration of the present embodiment, since the adhesive layer does not exist between the planar optical waveguide element and the submount, the distance between the optical waveguide and the submount depends on the thickness of the protective film 205. Is determined. Thus, high-precision positioning becomes possible, and highly efficient optical coupling is realized.
[0171]
In this embodiment, an ultraviolet curable adhesive is used as the adhesive, but the same effect can be obtained by using another adhesive. In particular, if an adhesive that shrinks after bonding is used, the adhesion to the submount is further increased, so that a better effect can be obtained.
[0172]
An optical waveguide formed on a dielectric substrate or a ferroelectric substrate by an ion exchange method such as proton exchange or a diffusion method such as Ti diffusion generally has a depth of about 2 μm. Therefore, more precise adjustment is required than in the case of an optical integrated device using an optical fiber. Therefore, if grooves can be formed on the submount as in the present embodiment to improve the alignment adjustment accuracy in the substrate thickness direction, the practical effect is large. Specifically, for example, a DBR semiconductor laser and LiNbO₃Substrate and LiTaO₃The present invention exerts a great practical effect on a short wavelength blue light source composed of an optical waveguide type wavelength conversion device having a periodically poled region on a substrate.
[0173]
In the above description, the groove 202 is formed in a direction perpendicular to the direction of the optical waveguide 209 of the planar optical waveguide device 204. On the other hand, in order to realize a uniform heat radiation state, the groove 202 is formed in a direction parallel to the optical waveguide 209, similarly to the case described with reference to FIGS. 13 and 14 in the eighth embodiment. Preferably, it is formed. Particularly, in the optical waveguide type wavelength conversion device, since the temperature distribution inside the element greatly affects the element characteristics such as the wavelength conversion efficiency, a large effect can be obtained by realizing a uniform temperature distribution by forming grooves in parallel directions. .
[0174]
(Tenth embodiment)
In the ninth embodiment, when fixing a planar optical waveguide element (optical waveguide type wavelength conversion device) with an adhesive (ultraviolet curable adhesive), a groove is formed on the submount to achieve high-precision mounting. The device configuration for realizing is described. On the other hand, in the present embodiment, a configuration and a method of fixing a planar optical waveguide element (optical waveguide type wavelength conversion device) on a submount by molecular bonding force without using an adhesive such as an ultraviolet curing adhesive. Will be described with reference to FIG. 17 and FIG. In this case, since nothing exists between the planar optical waveguide element and the submount, the same effect as in the second embodiment can be obtained.
[0175]
FIG. 17 is a perspective view schematically showing the above configuration, and FIG. 18 is a cross-sectional view taken along a line XVIII-XVIII in FIG. 17 including a center line between the cross keys 306. The state where the chip 303 and the optical waveguide type wavelength conversion device 304 are mounted on the submount 301 is shown.
[0176]
In FIG. 17, the entire surface of the submount 301 made of silicon (Si) is oxidized, that is, the entire surface of the submount 301 is made of SiO.₂It is preferable that the layer 302 be formed. This is because MgO-doped LiNbO₃This is for improving the bonding with the substrate. The portion for fixing the semiconductor laser chip 303 has the shape as described in the first embodiment with reference to FIGS. 13 and 14, and the electrodes and the solder are deposited. Then, the semiconductor laser chip 303 is mounted at a desired position on the submount 301 by junction-down such that the surface on the active layer side is on the submount 301 side in the same manner as in the eighth embodiment. Specifically, the semiconductor laser chip 303 is, for example, a 100 mW class distributed Bragg reflection type (DBR) AlGaAs semiconductor laser oscillating in a TE mode, and its oscillation wavelength is 850 nm.
[0177]
Next, a method of mounting the planar optical waveguide element 304 on the submount 301 will be described.
[0178]
As in the second embodiment, the planar optical waveguide element 304 is an x-cut MgO-doped LiNbO₃An optical waveguide type wavelength conversion device 304 in which a proton exchange optical waveguide and a periodically poled region are formed on a substrate is used. In this case, since the optical waveguide manufactured on the x-cut substrate can guide only the light of the TE mode, the planar type direct coupling is possible.
[0179]
On the surface of the optical waveguide type wavelength conversion device 304, a protective film 307 such as SiO₂A sputtered film 307 is formed. SiO on submount 301₂The surface of the layer 302 and the mounting surface of the optical waveguide type wavelength conversion device 304 are sufficiently cleaned before mounting.
[0180]
At the time of mounting, the cross key 305 and the cross key 306 are image-recognized, their center lines are aligned, and the distance between the end face of the semiconductor laser chip 303 and the end face of the optical waveguide type wavelength conversion device 304 is about 3 μm. (See FIG. 18). At that position, the optical waveguide type wavelength conversion device 304 is brought into optical contact with the submount 301 while applying a constant pressure to the optical waveguide type wavelength conversion device 304, and is maintained at a temperature of about 300 ° C. for about 30 minutes. In this heating and holding step, the optical waveguide is also annealed at the same time under the above conditions, and the optical waveguide type wavelength conversion device 304 used in the present embodiment is manufactured in consideration of this point in advance.
[0181]
By performing such an annealing step, in the present embodiment, both can be fixed without any intervening between the optical waveguide type wavelength conversion device 304 and the submount 301. Thus, since the height of the optical waveguide of the optical waveguide type wavelength conversion device 304 can be adjusted only by the thickness accuracy of the protective film 307, high-precision fixing can be realized.
[0182]
Specifically, with the configuration of the present embodiment, a coupling efficiency of about 70% can be achieved with a high yield. Further, by changing the current injected into the DBR region of the semiconductor laser chip 303 to vary the oscillation wavelength, and matching the oscillation wavelength of the semiconductor laser 303 with the phase matching wavelength of the optical waveguide type wavelength conversion device 304, the wavelength conversion device Blue light having a wavelength of 425 nm can be obtained from 304 at an output of about 10 mW.
[0183]
(Eleventh embodiment)
In the eleventh embodiment, referring to the cross-sectional view of FIG.₂The configuration of a submount for mounting a semiconductor laser chip having two electrodes such as a DBR semiconductor laser using layers will be described.
[0184]
In FIG. 19, a submount 401 made of silicon (Si) has a SiO.sub.₂A layer 402 is provided, on which an Au layer 403 as an electrode and a solder (Au / Sn) layer 404 are deposited. In order to separate these electrode layers into predetermined regions, SiO 2₂A groove 410 is formed by etching the layer 402, the Au layer 403, and the solder (Au / Sn) layer 404. The DBR semiconductor laser chip 405 includes an active layer region 406 for giving a gain and a distributed Bragg reflection region (DBR region) 407 for controlling an oscillation wavelength, and is electrically separated into respective regions 406 and 407. Electrodes 408 and 409 are formed. As in the present embodiment, a groove 410 is provided in the submount 401, and a portion corresponding to the active layer region 406 and a portion corresponding to the DBR region 407 of the DBR semiconductor laser chip 405 are electrically separated from each other. Since the current injected into the layer region 406 and the current injected into the DBR region 407 can be completely separated, a stable operation can be realized.
[0185]
The DBR semiconductor laser chip 405 is fixed to the submount 401 by junction down so that the surface on the active layer side is on the submount side. In an AlGaAs-based DBR semiconductor laser, a high-resistance layer is present in the DBR region, and the temperature of the high-resistance layer rises due to current injection to change the refractive index, thereby changing the wavelength. In this case, in the junction-down mounting in which the side closer to the active layer is located on the submount side, the heat radiation from the DBR region to the submount is improved, so that the wavelength tunable characteristic is rather deteriorated. In order to prevent such an adverse effect, a groove having an appropriate shape is formed in a portion of the submount where the optical waveguide portion in the DBR region of the DBR semiconductor laser is in contact, and the heat radiation characteristic thereof is intentionally deteriorated. Suppression of deterioration of the wavelength tunable characteristic or improvement of the wavelength tunable characteristic can be realized.
[0186]
In the mounting configuration for the DBR semiconductor laser chip 405 described in the present embodiment, the semiconductor laser chip having two electrodes is configured by using the eighth to tenth embodiments described above and the twelfth to fourteenth embodiments described below. It is applicable when used in the configuration of.
[0187]
(Twelfth embodiment)
In this embodiment, a direct coupling type optical integrated device in which an array type semiconductor laser chip having a plurality of light emitting portions and a planar type optical waveguide element having a plurality of optical waveguides are mounted on a submount is shown in FIGS. This will be described with reference to FIG. FIG. 20 is a perspective view schematically showing the above configuration, and FIG. 21 is a cross-sectional view along the line XXI-XXI in FIG.
[0188]
In the configuration of the present embodiment, a 100 mW class array-type distributed Bragg reflection (DBR) AlGaAs semiconductor laser chip 502 having ten light-emitting portions 503 is used as the semiconductor laser chip 502. Further, as the planar optical waveguide element 504, x-cut MgO-doped LiNbO₃An optical waveguide type wavelength conversion device 504 in which ten proton exchange optical waveguides 505 and a periodically poled region 506 are formed on a substrate is used.
[0189]
In the configuration of the present embodiment, the interval between the light emitting portions 503 of the array-type semiconductor laser chip 502 and the interval between the optical waveguides 505 of the optical waveguide type wavelength conversion device 504 are the same. Thus, optical coupling adjustment can be realized at the same time. It is preferable that the interval between the light emitting portions 503 of the array type semiconductor laser chip 502 and the interval between the optical waveguides 505 of the optical waveguide element 504 are both about 0.3 mm or more and about 1.0 mm or less.
[0190]
As the array type semiconductor laser chip 502, one that oscillates in the TE mode is used. In this case, the optical waveguide manufactured on the x-cut substrate can guide only the light in the TE mode, and thus, the planar type direct coupling is realized.
[0191]
Cross keys 511 and 516 for image recognition are formed at both ends of the optical waveguide type wavelength conversion device 504 and the semiconductor laser chip 502, respectively. Cross keys 510 and 515 are also formed on the surface of the submount 501. These cross keys are formed by the same mask, and the positional relationship between the light emitting portion 503 on the array type semiconductor laser chip 502 and the cross key 516 is determined by the cross direction of the optical waveguide 505 on the optical waveguide type wavelength conversion device 504. The formation positions of the keys 511 are adjusted so as to be the same as the positional relationship with the keys 511.
[0192]
On the surface of the optical waveguide type wavelength conversion device 504, a protective film 508 for adjusting the thickness is formed. The optical waveguide type wavelength conversion device 504 is fixed on a silicon (Si) submount 501 in which a groove 507 is formed as in the ninth embodiment. An ultraviolet-curing adhesive 509 is injected into the groove 507 as an adhesive. Since the adhesive 509 is injected into the groove 507 formed on the submount 501, the thickness of the protective film 508 on the optical waveguide type wavelength conversion device 504 can be controlled with high precision, and the substrate thickness can be controlled. Position adjustment in the vertical direction (y direction) can be easily performed.
[0193]
Referring to the cross-sectional view of FIG. 21, the groove on which the array-type semiconductor laser chip 502 is mounted on the submount 501 is not formed as described in the eighth embodiment. In this part, SiO 2 is used as an insulating layer.₂A layer 512 is formed, and further thereon, an Au layer 513 as an electrode and a solder (Au / Sn) layer 514 are formed such that the Au layer 513 is located below the light emitting portion 503 of the array type semiconductor laser chip 502. It is formed with a predetermined electrode pattern.
[0194]
In the configuration of this embodiment, the thickness of the Au layer 513 and the thickness of the solder (Au / Sn) layer 514 are controlled with high precision, and the pressure applied to the array-type semiconductor laser chip 502 and the temperature at the time of solder melting are controlled with high precision. By doing so, the mounting accuracy (alignment adjustment accuracy) in the y direction is improved.
[0195]
Next, a mounting method for the configuration of the present embodiment will be described.
[0196]
First, the array type semiconductor laser chip 502 is fixed on the submount 501 by junction down so that the surface on the active layer side is on the submount 501 side. Next, in order to melt the solder (Au / Sn) layer 514, the submount 501 is pulse-heated. In this heating step, since the temperature of the submount 501 rises to about 300 ° C., if the optical waveguide type wavelength conversion device 504 is fixed first and then the heating step for fixing the array type semiconductor laser chip 502 is performed, The operating characteristics of the wavelength conversion device 504 may change. Therefore, it is preferable to fix the array-type semiconductor laser chip 502 by heating before fixing the optical waveguide type wavelength conversion device 504.
[0197]
Thereafter, as in the eighth embodiment, the array type semiconductor laser chip 502 and the submount 501 are image-recognized by separate cameras, and the precision stage is adjusted so that the center lines A5 and B5 between the cross keys 515 and 516 match. Then, the submount 501 is heated to perform a fixing process.
[0198]
After mounting the array type semiconductor laser chip 502, the center lines between the cross keys 510 and 511 on the optical waveguide type wavelength conversion device 504 and the submount 501 coincide with each other as in the ninth embodiment, and the array type semiconductor laser chip 502 is mounted. The optical waveguide type wavelength conversion device 504 is moved so that the distance between the emission surface of the semiconductor laser chip 502 and the incident surface of the optical waveguide type wavelength conversion device 504 becomes about 3 μm. Thereafter, the optical waveguide type wavelength conversion device 504 is fixed by applying ultraviolet light while applying a constant pressure.
[0199]
In the configuration of the present embodiment, the interval between the light emitting portions 503 of the array type semiconductor laser chip 502 and the interval between the optical waveguides 505 of the optical waveguide type wavelength conversion device 504 match, so that all of the ten optical waveguides 505 are used. On the other hand, a coupling efficiency of 60% or more is realized. By changing the oscillation wavelength by changing the current injected into the DBR region of the array-type semiconductor laser chip 502 and making the oscillation wavelength of the semiconductor laser 502 coincide with the phase matching wavelength of the optical waveguide type wavelength conversion device 504, the optical waveguide 505 is obtained. Provide a blue output of about 10 mW.
[0200]
As described above, if the interval between the light emitting portions of the array-type semiconductor laser chip 502 having a large number of light emitting portions and the interval between the optical waveguides of the wavelength conversion device 504 having a large number of optical waveguides 505 are matched, the number of the optical waveguides for a large number of optical waveguides can be increased. Since the coupling adjustment can be performed at the same time, an array type short wavelength light source can be easily realized.
[0201]
In the above description of the present embodiment, as the optical waveguide type wavelength conversion device 504, MgO-doped LiNbO₃Although the configuration fabricated on the substrate is used, the LiTaO₃Substrate and KTiOPO₄The same effect can be obtained by using an optical waveguide type wavelength conversion device manufactured on a substrate.
[0202]
Instead of performing the alignment adjustment while observing the distance between the array-type semiconductor laser chip 502 and the optical-waveguide-type wavelength conversion device 504 as described above, as shown in the cross-sectional view of FIG. If a Ta film 517 having a thickness of about 1 μm is formed on the end face of the wavelength conversion device 504, a gap having a predetermined size can be secured between the semiconductor laser 502 and the wavelength conversion device 504 with high accuracy. As a result, a more practical device configuration that can easily achieve alignment adjustment in the z direction can be obtained. Instead of the Ta film 517, various metal films or dielectric films can be appropriately selected and provided.
[0203]
In the configuration of FIG. 22, the same components as those in the configuration depicted in FIG. 20 or FIG. 21 are denoted by the same reference numerals, and description thereof will be omitted.
[0204]
(Thirteenth embodiment)
In the twelfth embodiment, the submount, the array-type semiconductor laser chip, and the cross key formed on the optical waveguide type wavelength conversion device are image-recognized, thereby performing a mounting process by passive alignment adjustment, Short wavelength light source is realized. On the other hand, in the present embodiment, an active adjustment method for causing the array-type semiconductor laser chip to emit light and performing the alignment adjustment while actually coupling the laser light to the optical waveguide is schematically illustrated in FIGS. 23 and 24. This will be described with reference to FIGS.
[0205]
In FIG. 23, an array-type semiconductor laser chip 602 is mounted junction-down on a silicon (Si) submount 601 by the same method as in the twelfth embodiment. As the array type semiconductor laser chip 602, for example, a 100 mW class array type distributed Bragg reflection type (DBR) AlGaAs semiconductor laser chip 602 having 50 light emitting units 604 is used. The width of the semiconductor laser chip 602 is typically about 20 mm, and the interval between the light emitting parts is typically about 400 μm.
[0206]
On the other hand, as the planar optical waveguide element 603, x-cut MgO-doped LiNbO₃An optical waveguide type wavelength conversion device 603 having a proton exchange optical waveguide 605 and a periodically poled region formed on a substrate is used. The interval between the optical waveguides 605 of the optical waveguide type wavelength conversion device 603 is also designed to be about 400 μm, and has a total of 50 optical waveguides 605.
[0207]
Note that a chip that oscillates in a TE mode is used as the array-type semiconductor laser chip 602. Since the optical waveguide fabricated on the x-cut substrate can guide only the light in the TE mode, the above-described configuration realizes the planar-type direct coupling.
[0208]
The optical waveguide type wavelength conversion device 603 is mounted on the submount 601 on which the groove 606 is formed, as in the twelfth embodiment. An ultraviolet curing adhesive 607 is injected into the groove 606 as an adhesive. On the other hand, a protective film 608 for adjusting the thickness is formed on the surface of the optical waveguide type wavelength conversion device 603, and a Ta film 609 having a thickness of about 1 μm for adjusting the gap is formed on the end face (FIG. 24). reference). As described above, since the protective film 608 and the Ta film 609 are formed on the surface of the optical waveguide type wavelength conversion device 603, the alignment in the y direction and the z direction can be easily adjusted as in the twelfth embodiment.
[0209]
Next, an alignment adjustment method in the x direction in the configuration of the present embodiment will be described with reference to FIG.
[0210]
In the present embodiment, unlike the twelfth embodiment, a cross key for adjustment is not formed on the optical waveguide type wavelength conversion device 603. Instead, in order to collimate the laser light emitted from both ends of the optical waveguide type wavelength conversion device 603, a lens barrel 610 to which two aspheric lenses with a numerical aperture of 0.5 are fixed is used. Specifically, current flows into the first and 50th active layer portions (shown as (1) and (50) in the figure) of the semiconductor laser chip 602 to cause laser oscillation. The laser beams 613 emitted from the corresponding first and 50th optical waveguides 605 of the optical waveguide type wavelength conversion device 603 are collimated by the lens barrel 610, and the outputs thereof are detected by the photodetectors 611 and 612. Then, while adjusting the position of the optical waveguide type wavelength conversion device 605 in the x direction, the adhesive is cured by irradiating ultraviolet light at the position where the sum of the outputs detected by the photodetectors 611 and 612 is maximized. The device 603 is fixed.
[0211]
In such an alignment method, the coupling efficiency for the two optical waveguides is typically about 70% each. Also, by adjusting the position of the optical waveguide type wavelength conversion device 603 so that the coupling efficiency is maximized in the two optical waveguides 605 at both ends, about 65% of each of the 50 optical waveguides 605 can be obtained. The above coupling efficiency is obtained.
[0212]
As described above, if the interval between the light-emitting portions of the array-type semiconductor laser chip 602 having a large number of light-emitting portions and the interval between the optical waveguides of the wavelength conversion device 603 having a large number of optical waveguides 605 are the same, a small number of optical waveguides can be obtained. By performing only the coupling adjustment, the coupling adjustment for the remaining many optical waveguides can be performed at the same time, so that an array-type short-wavelength light source can be easily realized.
[0213]
In the above description of the present embodiment, the alignment is adjusted using the light emitting portions and the optical waveguides at both ends. However, similar effects can be obtained by using the light emitting portion and the optical waveguide at the center. In addition, the alignment is adjusted so that the sum of the coupling efficiencies of the two optical waveguides is maximized. However, if the accuracy of forming the light emitting unit interval and the optical waveguide interval is high, only one light emitting unit is oscillated by laser. Even if only the light coupled to one corresponding optical waveguide is detected therefrom and the alignment is adjusted, the same effect can be obtained.
[0214]
On the other hand, three or more light-emitting portions may be used for alignment adjustment. However, if the number is too large, the adjustment method becomes substantially the same as the active adjustment method, a plurality of power supplies for laser oscillation are required, and the adjustment process becomes complicated, so that the practical effect is reduced.
[0215]
As in the present embodiment, by actually performing the laser oscillation to perform the coupling adjustment, it is possible to realize more accurate device fixing. When optical adjustment is performed by actually oscillating the laser, there is a risk that the semiconductor laser chip may be deteriorated. However, if only two of the 50 light emitting units are oscillated as in the present embodiment, the remaining laser light is emitted. There is no risk of deterioration of the light emitting unit, and optical adjustment close to passive adjustment is realized.
[0216]
(14th embodiment)
As a fourteenth embodiment of the present invention, mass production is achieved by combining the method of manufacturing the array type short wavelength light source described in the twelfth and thirteenth embodiments with a method of cutting into a pair of semiconductor laser chips and an optical waveguide. A method for producing a short-wavelength light source having a high level is described.
[0217]
In general, the process of fabricating an array-type short-wavelength light source consists of two processes. Specifically, the first step is a step of fixing the array type semiconductor laser chip to the submount by soldering, and the second step is fixing the planar optical waveguide element to the submount by an ultraviolet curing adhesive. This is the step of performing
[0218]
Further, the first step is a step of attaching the semiconductor laser chip to the tool and fixing the submount to the table, a step of recognizing the semiconductor laser chip and the cross key on the submount by a camera, and adjusting the position to a desired position; Fixing the semiconductor laser chip by heating the submount and melting the solder. The time required for image recognition and adjustment is about 120 seconds, and the time required to melt and fix the solder is about 30 seconds.
[0219]
In the second step, a step of attaching the optical waveguide type wavelength conversion device to the tool, a step of injecting an ultraviolet curing adhesive on the submount, and a cross key on the optical waveguide type wavelength conversion device and the submount are attached to the camera. And a step of irradiating ultraviolet rays to fix the optical waveguide type wavelength conversion device. The time required in the second step is about 120 seconds.
[0220]
Therefore, the process time required to produce a short wavelength light source is about 270 seconds per device. From this, when an integrated device is manufactured by fixing a semiconductor laser chip and an optical waveguide type wavelength conversion device one by one on a submount, a manufacturing time of about 270 seconds is required for each pair. The cost required for adjustment and fixing is greater than the cost. In order to spread integrated devices, high productivity and low cost are required, and the above-described manufacturing method cannot meet such requirements.
[0221]
On the other hand, in the array-type short-wavelength light source as in the twelfth or thirteenth embodiment, the time required for adjustment and fixing is almost the same as described above. Therefore, an array-type short-wavelength light source as in the twelfth or thirteenth embodiment is formed first, and then, as a third step, the array-type short-wavelength light source is cut into pairs, thereby reducing The time required for adjustment and fixing of the vehicle is greatly reduced.
[0222]
For cutting, a dicing saw or a laser processing machine can be used, and the time required for cutting by these means is about 100 seconds.
[0223]
Practically, cutting with a laser processing machine rather than a dicing saw causes less damage to a semiconductor laser chip and an optical waveguide type wavelength conversion device, and is more desirable in processing. Specifically, (1) a YAG laser, (2) an excimer laser, and (3) an ultraviolet laser based on a harmonic of oscillation light of a solid laser can be used as a light source of the laser processing machine. Has features.
[0224]
(1) YAG laser: Damage to the optical waveguide type wavelength conversion device is large because it is thermally processed.
[0225]
(2) Excimer laser: a mask for cutting is required due to poor light-collecting properties. However, since the light is in the ultraviolet region and has an additional effect due to the chemical reaction, it is possible to perform cutting with less heat generation and less damage.
[0226]
(3) Ultraviolet laser by harmonics of solid-state laser: high condensing property, large effect by chemical reaction, and small damage to device.
[0227]
In cutting with a dicing saw or a laser processing machine, it is necessary to secure an area of about 50 μm to about 100 μm as a cutting margin. In consideration of this point, it is desirable that the interval between the light emitting portions of the array type semiconductor laser and the interval between the optical waveguides of the optical waveguide type wavelength conversion device be about 0.3 mm or more and about 1.0 mm or less. If these distances exceed about 1.0 mm, the number of devices obtained from one substrate decreases. Further, if the distance between them is smaller than about 0.3 mm, a sufficient margin cannot be secured.
[0228]
By performing the above-described series of three steps, an ultra-small short-wavelength light source is manufactured. At this time, the manufacturing time required for one short-wavelength light source is about 8 seconds (= 370 seconds / 50), and 450 ultra-small short-wavelength light sources per hour can be realized with one device. it can. As a result, a device with high mass productivity can be manufactured.
[0229]
When the fixing strength between the semiconductor laser chip or the optical waveguide type wavelength conversion device and the submount is weak, the device may be detached from the submount when cut with a dicing saw. Therefore, after applying a material such as a resist or wax that can be removed with an organic solvent to the optical coupling portion of the array type ultrashort wavelength light source, the semiconductor laser chip and the optical waveguide type wavelength conversion device are fixed, and then a cutting process is performed. If the applied material is removed with an organic solvent after cutting, cutting with less damage can be performed.
[0230]
In optical integrated devices, it is essential that semiconductor laser chips, optical fibers, optical waveguide devices, etc. be mounted on a submount and that laser light from a semiconductor laser be efficiently coupled to optical fibers and optical waveguide devices. It is. In particular, an optical waveguide formed on a dielectric substrate or a ferroelectric substrate by an ion exchange method such as proton exchange or a diffusion method such as Ti diffusion generally has a depth of about 2 μm. Alignment adjustment, for example, on the order of sub-microns, which is more accurate than an optical integrated device using a fiber, is required. For this reason, it is important to form a groove on the submount as described above to enhance the alignment adjustment accuracy in the substrate thickness direction. In particular, DBR semiconductor laser and LiNbO₃Substrate and LiTaO₃If the present invention is applied to a short-wavelength blue light source composed of an optical waveguide type wavelength conversion device having a periodically poled region on a substrate, the practical effect is large.
[0231]
When a semiconductor laser chip or an optical waveguide device is mounted on a submount via a solder or an adhesive, it is important to control the thickness of the solder or the adhesive. However, in practice, it is difficult to strictly control the thickness of the solder or the adhesive and perform submicron alignment adjustment in the thickness direction (y direction). On the other hand, if a groove is formed on the submount as in the present invention and a solder or an adhesive is injected into the groove, the adhesion between the semiconductor laser chip or the optical waveguide device and the submount is improved. High-precision mounting can be realized, and the practical effect is great.
[0232]
On the other hand, in order to further popularize optical integrated devices in the consumer field, it is necessary to further reduce the cost of direct-coupled modules, and for that purpose, high-productivity and high-precision modularization technology is required. It is said. As in the present invention, by using an array-type semiconductor laser having a large number of light emitting points and an optical waveguide device having a large number of optical waveguides, and having the light emitting point interval and the optical waveguide interval coincide, high accuracy is achieved. However, many optical couplings can be easily performed. Further, by cutting the array structure into individual structures each including one semiconductor laser and one optical waveguide by using a dicing saw or a laser processing machine, it becomes possible to manufacture devices with high mass productivity.
[0233]
【The invention's effect】
As described above, according to the present invention, in an integrated optical device configured by mounting a semiconductor laser and an optical waveguide element on a submount, the mounting accuracy in the substrate thickness direction (y direction) is improved, The laser light emitted from the semiconductor laser chip can be efficiently coupled to the optical waveguide of the optical waveguide device.
[0234]
According to the present invention, a semiconductor laser chip including a wavelength tunable semiconductor laser having an active layer region for providing a gain and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength is junction-down mounted on a submount. In the case of fixing by using, a stable wavelength variable characteristic and oscillation characteristic are realized by forming a groove on the submount surface for electrically separating a portion corresponding to the active layer region and a portion corresponding to the DBR region. be able to.
[0235]
Further, according to the present invention, an array type semiconductor laser chip having a plurality of (two or more) light emitting portions and a planar optical waveguide element having a plurality of (two or more) optical waveguides are mounted on a submount. In forming an integrated optical device, optical coupling between a large number of light emitting units and optical waveguides can be realized at the same time.
[0236]
Further, according to the present invention, an optical integrated device is supplied with high mass productivity.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an example of a configuration of a conventional blue light source using an optical waveguide type wavelength conversion device.
FIG. 2 is a diagram schematically illustrating an example of a configuration of a conventional blue light source using a domain-inverted waveguide device.
FIGS. 3A and 3B are a perspective view and a cross-sectional view schematically showing a configuration of a wavelength tunable semiconductor laser according to a first embodiment of the present invention.
FIGS. 4A and 4B are a perspective view and a sectional view schematically showing a configuration of a short wavelength light source according to a second embodiment of the present invention.
FIGS. 5A and 5B are a perspective view and a plan view schematically showing a configuration of a wavelength tunable semiconductor laser according to a third embodiment of the present invention.
FIGS. 6A and 6B are a perspective view and a sectional view schematically showing a configuration of a short wavelength light source according to a fourth embodiment of the present invention.
FIGS. 7A and 7B are a perspective view and a sectional view schematically showing a configuration of a wavelength tunable semiconductor laser according to a fifth embodiment of the present invention.
FIGS. 8A and 8B are a perspective view and a sectional view schematically showing a configuration of a short wavelength light source according to a sixth embodiment of the present invention.
FIGS. 9A and 9B are a perspective view and a plan view schematically showing a configuration of a wavelength tunable semiconductor laser according to a seventh embodiment of the present invention.
FIG. 10 is a perspective view schematically showing a configuration of an optical integrated device according to an eighth embodiment of the present invention.
FIG. 11 is a sectional view taken along lines XI-XI in FIG. 10;
FIG. 12 is a diagram for schematically explaining a mounting method in the optical integrated device of FIG. 11;
FIG. 13 is a perspective view schematically showing another configuration of the optical integrated device according to the eighth embodiment of the present invention.
FIG. 14 is a sectional view taken along lines XIV-XIV in FIG. 13;
FIG. 15 is a perspective view schematically showing a configuration of an optical integrated device according to a ninth embodiment of the present invention.
FIG. 16 is a sectional view taken along lines XVI-XVI in FIG. 15;
FIG. 17 is a perspective view schematically showing a configuration of an optical integrated device according to a tenth embodiment of the present invention.
FIG. 18 is a sectional view taken along lines XVIII-XVIII in FIG. 17;
FIG. 19 is a sectional view schematically showing a configuration of an optical integrated device according to an eleventh embodiment of the present invention.
FIG. 20 is a perspective view schematically showing a configuration of an optical integrated device according to a twelfth embodiment of the present invention.
FIG. 21 is a sectional view taken along lines XXI-XXI in FIG. 20;
FIG. 22 is a sectional view schematically showing another configuration of the optical integrated device according to the twelfth embodiment of the present invention.
FIG. 23 is a perspective view illustrating a method for adjusting the alignment of an optical integrated device according to a thirteenth embodiment of the present invention.
FIG. 24 is a plan view illustrating a method for adjusting the alignment of an optical integrated device according to a thirteenth embodiment of the present invention.
FIG. 25 is a perspective view schematically showing another configuration of the optical integrated device according to the eighth embodiment of the present invention.
[Explanation of symbols]
1 DBR semiconductor laser
2 Active layer area
3 DBR area
4 Junction (active layer)
5, 6 Si submount
7 SiO₂layer
8 electrodes
9 Solder layer
10 grooves
11 Optical waveguide type wavelength conversion device
12 wires
13 electrodes
14 Solder layer
15a, 15b electrodes
16 Protective film
20 Si submount
21 grooves
22 SiO₂layer
23 electrodes
24 Solder layer
25 wires
26 Si submount
27 grooves
28 SiO₂layer
29 electrodes
30 solder layer
31 grooves
35 Submount
36 electrodes
37 Solder layer
38 wires
39 Submount
40 electrodes
41 Solder layer
42 grooves
45 DBR semiconductor laser
46 Active layer area
47 Phase compensation area
48 DBR area
49 Submount
50 grooves
51 electrodes
52 Solder layer
101 Submount
102 SiO₂layer
103 groove
104 Au layer
105 solder layer
106 Semiconductor laser chip
107, 108 Four-way controller
109 V-groove
110 Optical waveguide device (optical fiber)
111, 112 camera
113 tools
114 units
115 Submount
116 SiO₂layer
117 grooves
118 Au layer
119 Solder layer
120 Semiconductor laser chip
121, 122 Four-way controller
123 V groove
124 optical waveguide device (optical fiber)
125 x cut MgO doped LiNbO₃substrate
126 Proton exchange optical waveguide
127 Periodically domain-inverted region
133 Escape groove
201 Submount
202 groove
203 Semiconductor laser chip
204 Planar type optical waveguide device (optical waveguide type wavelength conversion device)
205 protective film
206 adhesive (ultraviolet curing adhesive)
207, 208 Four-way controller
209 Optical waveguide
210 Domain-inverted region
301 Submount
302 SiO₂layer
303 semiconductor laser chip
304 Planar type optical waveguide device (optical waveguide type wavelength conversion device)
305, 306 Four-way controller
307 protective film
401 Submount
402 SiO₂layer
403 Au layer
404 solder layer
405 DBR semiconductor laser chip
406 Active layer area
407 DBR area
408, 409 electrodes
410 groove
501 Submount
502 Array type semiconductor laser chip
503 Light emitting unit
504 Planar type optical waveguide device (optical waveguide type wavelength conversion device)
505 Optical waveguide
506 domain-inverted region
507 groove
508 Protective film
509 adhesive (ultraviolet curing adhesive)
510, 511 Four-way controller
512 SiO₂layer
513 Au layer
514 solder layer
515, 516 Four-way controller
517 Ta film
601 submount
602 Array type semiconductor laser chip
603 Planar optical waveguide device (optical waveguide wavelength conversion device)
604 Light emitting unit
605 Optical waveguide
606 groove
607 adhesive (ultraviolet curing adhesive)
608 protective film
609 Ta film
610 lens barrel
611,612 Photodetector
613 laser light

Claims (4)

A submount,
A semiconductor laser chip having at least an active layer region and a distributed Bragg reflection region, which is mounted on the submount,
With
The semiconductor laser chip, as the epitaxial growth surface facing the said submount, and as a heat radiation state of the heat radiation state and the distributed Bragg reflector region of the active layer region is different, are mounted on the said submount ,
The contact area of the active layer region to the submount and the contact area of the distributed Bragg reflection region to the submount are different,
Tunable semiconductor laser. An optical integrated device having at least a semiconductor laser mounted on a submount and an optical waveguide device, wherein the semiconductor laser is the wavelength tunable semiconductor laser according to claim 1. A submount,
A semiconductor laser chip having at least an active layer region and a distributed Bragg reflection region, which is mounted on the submount,
With
The wavelength tunable semiconductor laser, wherein the semiconductor laser chip is mounted on the submount such that an epitaxial growth surface faces the submount and only the active layer region is in contact with the submount. An optical integrated device having at least a semiconductor laser mounted on a submount and an optical waveguide device, wherein the semiconductor laser is the wavelength tunable semiconductor laser according to claim 3 .

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