JP2002314183A - Method and device for manufacturing coherent light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize highly precise optically coupled adjustment and mounting in a coherent light source constituted of a semiconductor laser and a planar optical waveguide device. SOLUTION: At the time of mounting the optical waveguide device on a submount 7 to which a semiconductor laser 1 is fixed, current is injected to the semiconductor laser 1 and light is emitted. A picture detector 8 positioned above the submount 7 detects the position of the light emitting point of the semiconductor laser 1. The relative position of the optical waveguide of the optical waveguide device is adjusted with the detected position of the light emitting point as a reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a coherent light source and an apparatus for manufacturing the same. More specifically, the present invention relates to a method and an apparatus for mounting an optical waveguide device that constitutes a coherent light source integrally with a semiconductor laser and requires optical coupling adjustment with the semiconductor laser.

[0002]

2. Description of the Related Art An optical waveguide type second harmonic generation (hereinafter, referred to as "SHG") device (hereinafter, referred to as "SHG") device of a quasi-phase matching (hereinafter, referred to as "QPM") type as a compact short wavelength light source. -SHG device) has attracted attention (Yamamoto et al., Optics Letters)
Vol.16, No.15, 1156 (1991)).

FIG. 14 shows a schematic configuration of an SHG blue light source using an optical waveguide type QPM-SHG device.

As shown in FIG. 14A, a distributed Bragg reflector (hereinafter referred to as “DBR”) is used as a semiconductor laser.
A tunable DBR semiconductor laser 54 having a region is used. The tunable DBR semiconductor laser 54 has a wavelength of 0.8
100mW class AlGaAs wavelength tunable DBR in 5μm band
A semiconductor laser, the active layer region 56 and the phase adjustment region 5
7 and a DBR region 58. And
By simultaneously changing the injection current into the phase adjustment region 57 and the DBR region 58, the oscillation wavelength can be continuously changed.

[0005] As shown in FIG. 14 (b), an optical waveguide type QPM-SHG device 55 as a wavelength conversion element has a capacity of 0.1 mm.
An optical waveguide 60 and a periodically poled region 61 formed on an X-plate MgO-doped LiNbO ₃ substrate 59 having a thickness of 5 mm
It is composed of The optical waveguide 60 is formed by proton exchange in pyrophosphoric acid. The periodic domain-inverted region 61 is formed by forming a comb-shaped electrode on the X-plate MgO-doped LiNbO ₃ substrate 59 and applying an electric field.

In the SHG blue light source having the above configuration, 1
The tunable DBR semiconductor laser 54 and the optical waveguide type QPM-SHG device 55 are connected to the SPM so that 60 mW of laser light is coupled to the optical waveguide 60 with respect to the laser output of 00 mW.
It is mounted on the i-submount 62. Then, the phase adjustment region 57 of the wavelength tunable DBR semiconductor laser 54 and the DBR
By controlling the amount of current injected into the region 58, the oscillation wavelength is fixed within the tolerance of the phase matching wavelength of the optical waveguide type QPM-SHG device (wavelength conversion device) 55. When this SHG blue light source is used, blue light with a wavelength of 425 nm can be obtained at about 10 mW. The obtained blue light has a transverse mode of TE ₀₀ mode, has a diffraction-limited light-collecting characteristic, and has a noise characteristic of relative noise intensity. It is as small as −140 dB / Hz or less.

[0007] In the field of optical communication, a semiconductor laser, an electronic element,
Development of an optical module in which optical fibers and the like are hybrid-integrated is regarded as important, and this technology is indispensable for miniaturization and cost reduction of the module. here,
What is important is to fix each element with high precision and minimize the transmission loss. As such an optical module, a surface mount optical module has been realized by using a Si-V groove substrate and directly coupling a semiconductor laser and a single mode fiber (1997 IEICE General Conference C-3-) 63). In this surface mount optical module, an alignment key is formed on the Si substrate and the semiconductor laser, and the active layer of the semiconductor laser is adjusted with high precision at the center of the V-groove by recognizing the alignment key as an image. The optical fiber is mounted in the V groove. The V-groove is formed with high precision by anisotropic etching of the Si substrate. From the above, the mounting variation is x
The direction is suppressed to about ± 0.61 μm and the z direction to about ± 1 μm.

[0008]

In an optical module in which a semiconductor laser and an optical fiber are integrated, an optical fiber is mounted in a V-groove formed on a Si submount, and the semiconductor laser is mounted using the V-groove as a reference position. You. Here, the optical fiber has a cylindrical shape, a core portion (light propagation region) is formed at the center of the optical fiber, and the diameter of the optical fiber is controlled with high precision. Also,
The V-groove formed on the Si submount is also formed with high precision using anisotropic etching of Si. Therefore, the core portion, which is the center of the optical fiber, is mounted with high accuracy on the Si submount.

However, in mounting the semiconductor laser and the optical fiber, the mounting accuracy of the semiconductor laser becomes a problem.
An adjustment marker for mounting a semiconductor laser is formed on the Si submount. The adjustment marker is V
The groove can be formed with high accuracy. On the other hand, it is difficult to form the adjustment marker on the semiconductor laser with high accuracy. That is, regrowth is performed on the active layer, and finally, metallization is formed as an electrode. At this time, it is necessary to form an adjustment marker for the waveguide in the active layer, and variations between lots are required. Considering 1μ
The accuracy is about m.

A planar optical waveguide device having an optical waveguide formed on a LiNbO ₃ substrate by a method such as proton exchange (in the present invention, an optical waveguide device other than an optical waveguide device having an optical waveguide layer coaxially at the center of an optical fiber). A waveguide device is defined as a "planar optical waveguide device."
In, control in the thickness direction from the substrate surface can be performed with high accuracy. However, it is difficult to control the position of the optical waveguide in the lateral direction with respect to the external shape of the device with high accuracy by cutting, polishing, or the like.

The optical waveguide type QPM shown in the above prior art
In the optical coupling between the SHG device and the semiconductor laser, the coupling tolerance is such that when the optical waveguide type QPM-SHG device is moved in each direction from the position P where the maximum coupling efficiency is obtained, the coupling efficiency is reduced by half. Assuming that the movement amount from the position P is ± 1 μm in the lateral direction and ± 0.
It is about 8 μm. Therefore, adjustment markers are respectively formed on the semiconductor laser and the optical waveguide type QPM-SHG device, and the semiconductor laser and the optical waveguide type QPM-SHG are detected while detecting these adjustment markers with a CCD camera or the like.
When the device is mounted on a Si submount, it is difficult to obtain the maximum coupling efficiency.

In an optical waveguide type wavelength conversion device utilizing SHG (second harmonic generation), the conversion efficiency is proportional to the power incident on the optical waveguide, and the obtained harmonic light power is equal to the output of the semiconductor laser. Since it is proportional to the power, improvement of coupling efficiency and reduction of variation between samples are indispensable.

The present invention has been made to solve the above-mentioned problems in the prior art, and realizes highly accurate optical coupling adjustment and mounting in a coherent light source composed of a semiconductor laser and a planar optical waveguide device. The purpose is to provide a way to:

[0014]

In order to achieve the above object, a first method of manufacturing a coherent light source according to the present invention comprises the steps of:
A step of injecting a current into the semiconductor laser to emit light, and detecting a position of a light emitting point of the semiconductor laser by an image detector located above the submount. According to the first manufacturing method of the coherent light source, the relative position of the optical waveguide of the optical waveguide device can be easily adjusted based on the position of the detected light emitting point.

In the first method of manufacturing a coherent light source according to the present invention, it is preferable to fill a gas serving as a scatterer when detecting the position of the light emitting point of the semiconductor laser. According to this preferred method, the position of the light emitting point of the semiconductor laser can be detected by scattering the light emitted from the semiconductor laser and detecting the scattered light with the image detector located above the submount. it can.

In the first method of manufacturing a coherent light source according to the present invention, it is preferable that the position of the light emitting point is detected based on a point at which the light intensity of the semiconductor laser becomes maximum. In this case, the position of the light emitting point is
It is preferable that a straight line passing through the point where the light intensity becomes maximum intersects the emission end face of the semiconductor laser almost perpendicularly.

In the first method of manufacturing a coherent light source according to the present invention, it is preferable that the image detector is located in a direction normal to an upper surface of the submount. In this case, it is preferable that a scattering surface or a reflecting surface is formed on the submount near the emission end face of the semiconductor laser. According to this preferred method, the light emitted from the semiconductor laser is scattered or reflected, and the scattered light or the reflected light is detected by the image detector located above the submount, so that the position of the light emitting point of the semiconductor laser is determined. Can be detected. In this case, it is preferable that the amount of light guided to the scattering surface or the reflection surface is equal to or less than half the amount of light emitted from the semiconductor laser. This is because if the light guided to the scattering surface or the reflection surface becomes half or more of the amount of light emitted from the semiconductor laser, the light coupling efficiency is reduced. In this case, it is preferable that the image detector is provided at a position inclined forward with respect to a normal passing through the light emitting point. According to this preferred method, the emission end face of the semiconductor laser is observed obliquely, so that the light emitting point position on the emission end face of the semiconductor laser can be directly observed. In this case, it is preferable that a scattering surface or a reflection surface is further formed on the submount near the emission end face of the semiconductor laser. In this case, it is preferable that the amount of light guided to the scattering surface or the reflection surface is equal to or less than half the amount of light emitted from the semiconductor laser.

In the first method of manufacturing a coherent light source according to the present invention, it is preferable that the image detector is located in an optical axis direction of the semiconductor laser. According to this preferred method, the position of the light emitting point on the emission end face of the semiconductor laser can be directly observed.

A second method of manufacturing a coherent light source according to the present invention is a method of manufacturing a coherent light source in which an optical waveguide device is mounted on a submount on which a semiconductor laser is fixed, wherein the semiconductor laser emits light. The relative position of the optical waveguide of the optical waveguide device is adjusted on the basis of the position of the light emitting point detected by the optical waveguide.

Further, in the second method of manufacturing a coherent light source according to the present invention, after adjusting the relative position of the optical waveguide, it is obtained from the emission end face of the optical waveguide device by adjusting the optical coupling with the semiconductor laser. It is preferable to mount the optical waveguide device at a position where the optical output becomes substantially maximum. According to this preferred method, the optical coupling is adjusted so that the optical coupling efficiency is further maximized after the optical coupling operation, so that the maximum performance can be obtained.

Further, in the second method of manufacturing a coherent light source according to the present invention, the position adjustment direction of the light emitting point and the optical waveguide is (a) perpendicular to an optical axis, and And (b) a direction perpendicular to the optical axis and at least one of two directions defined perpendicular to the submount.

Further, in the second method of manufacturing a coherent light source according to the present invention, the optical waveguide device includes:
It is preferable that an adjustment marker is formed at a position symmetric with respect to the optical waveguide in the waveguide direction, and the position of the optical waveguide is detected by recognizing the adjustment marker. According to this preferred method, the position of the optical waveguide can be detected by determining the center line between the two adjustment markers. In this case, it is preferable that the adjustment marker is a stripe-shaped marker formed in parallel on both sides of the optical waveguide, and the position of the optical waveguide is set to a center line of the two stripe-shaped markers. According to this preferred method, the adjustment marker always exists on both sides of the emission end face regardless of the position of the emission end face of the optical waveguide device, so that the position of the optical waveguide can be detected with high accuracy. Further, in this case, it is preferable that the adjustment marker is detected by an image detector independent of the image detector. According to this preferred method, one image detector detects a light emitting point position on the emission end face of the semiconductor laser, and the other image detector detects an adjustment marker on the optical waveguide device,
The position of the light emitting point and the optical waveguide can be adjusted.

In the second method of manufacturing a coherent light source according to the present invention, it is preferable that the optical waveguide is formed on a substrate surface of the optical waveguide device. Since the semiconductor laser has an active layer on the surface, when the semiconductor laser and the optical waveguide device are mounted on the same submount, if the optical waveguide is formed on the substrate surface of the optical waveguide device, optical coupling can be easily performed. This is because it can be performed with high accuracy.

Further, in the second method of manufacturing a coherent light source according to the present invention, a current is injected into the semiconductor laser to emit light, and the light emitting point of the semiconductor laser is emitted by an image detector located above the submount. Is preferably detected. In this case, when detecting the position of the light emitting point of the semiconductor laser, it is preferable to fill a gas serving as a scatterer. Also, in this case,
It is preferable that the position of the light emitting point is detected based on a point at which the light intensity of the semiconductor laser becomes maximum. In this case, it is further preferable that the position of the light emitting point is a point at which a straight line passing through the point where the light intensity becomes maximum intersects substantially perpendicularly with the emission end face of the semiconductor laser. In this case, it is preferable that the image detector is located in a direction normal to the upper surface of the submount. In this case, it is preferable that a scattering surface or a reflection surface is further formed on the submount near the emission end face of the semiconductor laser. Further, in this case, the light guided to the scattering surface or the reflection surface,
It is preferable that the light amount is not more than half of the light amount emitted from the semiconductor laser. In this case, it is preferable that the image detector is further provided at a position inclined forward with respect to a normal passing through the light emitting point. Furthermore, in this case,
It is preferable that a scattering surface or a reflection surface is formed on the submount near the emission end face of the semiconductor laser. Further, it is preferable that the light guided to the scattering surface or the reflection surface is equal to or less than half the amount of light emitted from the semiconductor laser. In this case, it is preferable that the image detector is located in the optical axis direction of the semiconductor laser.

In the second method of manufacturing a coherent light source according to the present invention, it is preferable that the optical waveguide of the optical waveguide device is directly observed. In the case of a proton-exchanged optical waveguide, an adjustment marker is formed to allow direct observation of the optical waveguide, but in the case of a machined optical waveguide (ridge-type optical waveguide), the optical waveguide is directly connected. This is because it can be observed.

[0026] The structure of the apparatus for manufacturing a coherent light source according to the present invention is an apparatus for manufacturing a coherent light source in which an optical waveguide device is mounted on a submount on which a semiconductor laser is fixed. An image detector for detecting a position, a unit for adjusting a relative position of the optical waveguide of the optical waveguide device with reference to the position of the light emitting point, and a unit for measuring the intensity of light emitted from the optical waveguide of the optical waveguide device And characterized in that:

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to embodiments.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a coherent light source composed of a semiconductor laser and a planar optical waveguide device according to the first embodiment. FIG. 2 is a plan view of the planar optical waveguide device shown in FIG.

As shown in FIG. 1, in the coherent light source according to the present embodiment, a distributed Bragg reflector (hereinafter referred to as “DB”) is used as a semiconductor laser used as a fundamental wave.
R)) and an output 100 having a region and a phase adjustment region.
AlGaAs-based tunable DBR with mW and wavelength of 820 nm
A semiconductor laser 1 is used. This wavelength tunable DBR
In the semiconductor laser 1, the oscillation wavelength can be changed by injecting a current into the DBR region and the phase adjustment region at a constant ratio. As shown in FIG. 1 and FIG. 2, as a planar type optical waveguide device, a quasi phase matching (hereinafter referred to as “QPM”) type optical waveguide type second harmonic generation (hereinafter referred to as “SHG”) device is used. (Optical waveguide type QPM-SHG device) 2 is used. This optical waveguide type QPM-SHG device 2 is composed of an optical waveguide 4 and a periodic domain-inverted region 5 orthogonal to the optical waveguide 4 formed on an upper surface of an X-plate MgO-doped LiNbO ₃ substrate 3 having a thickness of 0.5 mm. I have. Optical waveguide type QPM-SH
The G device 2 can use a large nonlinear optical constant, is an optical waveguide type, and can have a long interaction length, so that high conversion efficiency can be realized. Note that, as shown in FIG.
On the SHG device 2, an adjustment marker 6 is formed at a position symmetrical in the waveguide direction with the optical waveguide 4 as a center.

As described above, the coherent light source in the present embodiment is constituted by the wavelength tunable DBR semiconductor laser 1 and the optical waveguide type QPM-SHG device 2.
HG laser. The wavelength tunable DBR semiconductor laser 1 is S
An optical waveguide type QPM fixed in advance on the i-submount 7
The SHG device 2 is mounted on the Si submount 7 after the optical coupling adjustment with the semiconductor laser 1 is completed.

In a SHG laser, the optical coupling adjustment is particularly important because the harmonic light output obtained by wavelength conversion is proportional to the square of the semiconductor laser output. Variable wavelength D
The BR semiconductor laser 1 and the optical waveguide type QPM-SHG device 2 have an active layer surface and an optical waveguide forming surface of Si, respectively.
It is mounted so as to be in contact with the upper surface of the submount 7. On the Si submount 7, a metal film as an electrode for a semiconductor laser and a solder film as a fixing member are formed, and the wavelength tunable DBR semiconductor laser 1 is mounted on the Si submount 7 by the solder film. Fixed to

Hereinafter, a method of manufacturing an optical waveguide type QPM-SHG device will be described.

As described above, the optical waveguide type QPM-SH
The G device 2 is a 0.5 mm thick X-plate MgO-doped Li
An optical waveguide 4 and a periodically domain-inverted region 5 orthogonal to the optical waveguide 4 are formed on an NbO ₃ substrate 3 (see FIGS. 1 and 2). The periodic domain-inverted region 5 is formed by forming a comb-shaped electrode on the X-plate MgO-doped LiNbO ₃ substrate 3 and applying an electric field. The optical waveguide 4 is formed in a direction perpendicular to the periodically domain-inverted region 5, and at this time, an adjustment marker 6 is also formed. That is, a Ta film is vapor-deposited on the X-plate MgO-doped LiNbO ₃ substrate 3, and a 5 μm-wide stripe mask for forming the optical waveguide 4 and an adjustment marker 6 are simultaneously formed by an exposure step and a dry etching step. You.
Then, proton exchange is performed in pyrophosphoric acid (200 ° C., 7 minutes), and an annealing process (330 ° C., 200 minutes) is performed, whereby the optical waveguide 4 is formed. Thereafter, the adjustment marker 6 is masked with a resist, and the Ta film is removed by performing wet etching. Finally,
By forming a protective film of SiO _2, an optical waveguide adjustment markers 6 are formed type QPM-SHG device 2
Is produced.

In the present embodiment, a stripe type marker is used as the adjustment marker 6. Since the stripe-shaped markers are always present on both sides of the emission end face of the optical waveguide type QPM-SHG device 2 irrespective of the position of the emission end face, the marker has a shape suitable for detecting the position of the optical waveguide 4 with high accuracy. is there. However, even if the marker has a shape such as a square, a circle, or a cross, the position of the optical waveguide 4 can be detected to a certain extent, so that there is no problem when high-precision optical coupling adjustment is not required. .

Next, an optical waveguide type QPM is mounted on a Si submount 7 on which the wavelength tunable DBR semiconductor laser 1 is fixed in advance.
A method of manufacturing an SHG laser (coherent light source) on which the SHG device 2 is mounted will be described with reference to FIGS. FIG. 3 is a process chart showing a method of manufacturing a coherent light source (position detection of a light emitting point) in the first embodiment of the present invention, and FIG. 4 is a method of manufacturing a coherent light source (light) in the first embodiment of the present invention. FIG.

First, as shown in FIG. 3 (a), the wavelength tunable DBR semiconductor laser 1 is
It is mounted on the i-submount 7. The tunable DBR semiconductor laser 1 is held by a chip hand, adjusted so as to be parallel to the Si submount 7, and mounted at a substantially desired position on the Si submount 7. And S
The i-submount 7 is heated to 300 ° C. to melt the solder, and the tunable DBR semiconductor laser 1 is fixed on the Si submount 7. In this case, the wavelength tunable DBR semiconductor laser 1 was fixed on the Si submount 7 by cooling while flowing N ₂ to avoid oxidation of the solder.

Next, while moving the optical waveguide type QPM-SHG device 2 on the Si submount 7, optical coupling with the wavelength tunable DBR semiconductor laser 1 is performed, and then the optical waveguide type QPM-SHG device 2 is connected to the Si submount. It is fixed on the mount 7. Optical coupling was performed as follows.

First, as shown in FIG. 3B, a current is injected into the electrode portion (active region) 12 of the Si submount 7,
The tunable DBR semiconductor laser 1 emits light. The tunable DBR semiconductor laser 1 used in the present embodiment had a threshold value of 30 mA and an output of 50 mW when a current of 100 mA was injected into the electrode portion. Variable wavelength D
Since the BR semiconductor laser 1 is mounted on the Si submount 7, there is no concern about deterioration even if the BR semiconductor laser 1 emits light as continuous light. Next, as shown in FIG. 3C, the light emitting point enlarged by the microscope lens 9 is observed using the CCD camera 8 and the microscope lens 9 located in the normal direction of the upper surface of the Si submount 7.

Here, a case where the focal position of the microscope lens 9 is adjusted to the height of the upper surface of the wavelength tunable DBR semiconductor laser 1 will be described. In this case, since the position of the light emitting point is not focused, it is obtained as a defocused image. In this embodiment, a microscope lens 9 having a magnification of 20 times and a numerical aperture NA of 0.4 is used, and as shown in FIG. A defocused light emitting point was observed slightly before the end face. The image observed by the CCD camera 8 is processed to detect a point A1 at which the light intensity becomes maximum, and the emission end face when a perpendicular line is drawn from the detected point A1 to the emission end face of the tunable DBR semiconductor laser 1. Is detected as the light emitting point position.

When detecting the position of the light emitting point of the wavelength tunable DBR semiconductor laser 1, it is desirable to fill a scatterer with a gas from dry ice, liquid nitrogen, or the like. This is the same in other embodiments described below.

Next, the positions of the optical waveguide type QPM-SHG device 2 and the wavelength tunable DBR semiconductor laser 1 are adjusted.

First, as shown in FIG. 4A, the distance between the end faces of the optical waveguide type QPM-SHG device 2 and the wavelength tunable DBR semiconductor laser 1 is adjusted. In the present embodiment, the distance between the end faces is set to 3 μm. In the present embodiment, the focal position of the microscope lens 9 is adjusted in advance to the height of the upper surface of the wavelength tunable DBR semiconductor laser 1, and specifically, the edges D1 and D2 of the respective end surfaces are observed with a CCD camera. The optical waveguide type QPM-SHG is applied to the wavelength tunable DBR semiconductor laser 1 on the Si submount 7 so that the distance between the edges D1 and D2 becomes 3 μm while detecting the light.
Device 2 was approached.

Next, as shown in FIGS. 4A and 4B, a direction perpendicular to both the normal direction and the optical axis direction of the upper surface of the Si submount 7 (the direction of the arrow in FIG. 4B). Adjust the position of. In this case, first, the optical waveguide type QPM-SHG
The position of the optical waveguide 4 of the device 2 is detected. On both sides of the optical waveguide 4 on the optical waveguide type QPM-SHG device 2,
Since the stripe-shaped adjustment marker 6 is formed at a position symmetrical in the waveguide direction with the optical waveguide 4 as a center, the edges E1 to E4 of the adjustment marker 6 are detected and the edge E1 is detected.
And the midline of the edge E2 and the midline of the edge E3 and the edge E4 to obtain the midline of each adjustment marker 6, and further obtain the midline between the two adjustment markers 6, thereby obtaining the position C of the optical waveguide 4. Can be detected. In this embodiment, since the optical waveguide 4 and the adjustment marker 6 are simultaneously formed using the same mask, the position of the optical waveguide 4 can be detected with high accuracy. Next, the wavelength tunable DB
Light emitting point A of R semiconductor laser 1 and optical waveguide type QPM-SH
The optical waveguide type QPM-SHG device 2 is arranged such that the position C of the optical waveguide 4 of the G device 2 coincides with the direction of the arrow.
Adjust the position of. Next, as shown in FIG.
In this state, the optical waveguide type QPM-SHG device 2 is placed in the normal direction of the upper surface of the Si submount 7 (FIG. 4C).
(In the direction of the arrow), that is, by moving the optical waveguide type QPM-SHG device 2 up and down, the light emitted from the tunable DBR semiconductor laser 1 is coupled to the optical waveguide 4. In this state, after the light emitted from the optical waveguide 4 is converted into parallel light by the collimating lens 10 and detected by the light receiving element 11,
Since the position detection accuracy of the light emitting point A and the position detection accuracy of the optical waveguide 4 are each approximately ± 0.5 μm, only the optical coupling efficiency of 20% of the desired optical coupling efficiency was obtained.

Next, an optical waveguide type QPM-SHG device 2 and a wavelength tunable DBR mounted on a Si submount 7 are described.
The optical coupling with the semiconductor laser 1 is adjusted. Specifically, the optical waveguide type QPM-SHG device 2 is moved from the state where the optical coupling efficiency is 20% of the desired optical coupling efficiency to the Si submount 7.
The intensity of light emitted from the optical waveguide 4 was measured by the light receiving element 11 while moving vertically and horizontally, and adjustment was made to increase the optical coupling efficiency. Then, at a position where the optical coupling efficiency is maximized, an optical waveguide type QPM-S is formed using an adhesive such as an ultraviolet curing agent manufactured by Three Bond.
The HG device 2 is mounted on the Si submount 7. Thereby, an optical coupling efficiency of 95% of the desired optical coupling efficiency was obtained. The decrease of 5% is due to the curing shrinkage of the adhesive, and it is possible to obtain higher bonding efficiency by selecting the adhesive. In the present embodiment, an adhesive is applied on the Si submount 7 after the optical coupling is adjusted. However, the same result can be obtained even if an adhesive is applied on the Si submount 7 before the optical coupling adjustment.

With the above-described optical coupling adjustment, the wavelength tunable DBR
The laser light emitted from the emission end face of the semiconductor laser 1 is coupled to the optical waveguide 4 of the optical waveguide type QPM-SHG device 2, and the laser light of 30 mW is coupled to the optical waveguide 4 for a laser output of 50 mW (optical coupling efficiency). 60%). The amount of current injected into the phase adjustment region and the DBR region of the wavelength tunable DBR semiconductor laser 1 is controlled, and the oscillation wavelength is changed to the optical waveguide type
By fixing the SHG device (wavelength conversion device) 2 within the tolerance of the phase matching wavelength, harmonic light having a wavelength of 425 nm was obtained at about 5 mW, and high-efficiency optical coupling and wavelength conversion were realized.

The adjustment marker 6 on the optical waveguide type QPM-SHG device (optical waveguide device) 2 can be formed with submicron accuracy, but the marker on the semiconductor laser is generally about several μm. It can only be formed with precision. In the mounting method of the coherent light source according to the present embodiment, the wavelength tunable DBR semiconductor laser 1 is actually caused to emit light, the light intensity distribution is observed to detect the position of the light emitting point, and the optical waveguide type QPM-SHG device ( Since the position of the optical waveguide 4 of the optical waveguide device 2 is detected using the adjustment marker formed at the same time as the optical waveguide 4, the light emitting point and the position of the optical waveguide 4 can be accurately obtained. In addition, since the optical coupling is adjusted so that the optical coupling efficiency is further maximized after the optical coupling operation, the maximum performance can be obtained, which is a practical mounting method.
The yield can be as high as 100%, which can greatly contribute to cost reduction.

In this embodiment, the optical waveguide type QPM-SHG device 2 is mounted on the Si submount 7 after detecting the semiconductor laser output obtained from the emission end face of the optical waveguide 4. By inspecting the semiconductor laser output obtained from the emission end face of the optical waveguide 4, the wavelength tunable D
Inspection of output characteristics of BR semiconductor laser 1 itself and optical waveguide 4
Can be performed at the same time, which is a more practical mounting method. In a SHG laser composed of the wavelength tunable DBR semiconductor laser 1 and the optical waveguide type QPM-SHG device 2, the wavelength of the wavelength tunable DBR semiconductor laser 1 is adjusted to the phase matching wavelength of the optical waveguide type QPM-SHG device 2. By doing so, blue light can be generated. Therefore, by inspecting the output of the obtained blue light, it is possible to evaluate the characteristics as an SHG laser, and the practical effect is large.

In the present embodiment, the optical waveguide 4
, It is difficult to observe the position of the optical waveguide 4. Therefore, an adjustment marker 6 is formed. However, when a Ti-diffused optical waveguide or a ridge-type optical waveguide is used, the optical waveguide can be directly observed, so that an adjustment marker is not required. By adjusting the relative position between the light emitting point of the semiconductor laser and the optical waveguide directly observed, the same effect as in the present embodiment can be obtained.

[Second Embodiment] FIG. 5 shows a second embodiment of the present invention.
FIG. 6 is a side view showing a light emitting point position detecting method according to the embodiment, and FIG. 6 is a plan view showing light emitting point positions.

As shown in FIG. 5, also in the present embodiment, C is located in the normal direction of the upper surface of Si submount 7.
The light emitting point enlarged by the microscope lens 9 is observed using the CD camera 8 and the microscope lens 9.

Here, a case where the focal position of the microscope lens 9 is adjusted to the height of the active layer region of the wavelength tunable DBR semiconductor laser 1 will be described.

The dashed line in FIG. 6 shows the outer shape of the wavelength tunable DBR semiconductor laser 1. Since the focal position of the microscope lens 9 is adjusted to the height of the active layer region of the wavelength tunable DBR semiconductor laser 1, the outer shape of the wavelength tunable DBR semiconductor laser 1 is out of focus, and a clear image is obtained. Absent. Therefore, the position of the light emitting point on the emission end face of the wavelength tunable DBR semiconductor laser 1 can be directly observed. As a result, by processing the image observed by the CCD camera 8 and detecting the point A3 where the light intensity becomes maximum, the light emitting point can be detected. In the present embodiment, since the height of the active layer region of the wavelength tunable DBR semiconductor laser 1, that is, the light emitting point is focused, a light emitting point smaller than that of the first embodiment is observed. Thus, the light emitting point can be detected with higher accuracy.

As shown in FIG. 7, the CCD camera 8 located in the normal direction of the upper surface of the Si submount 7 is inclined forward with respect to the normal passing through the light emitting point of the wavelength tunable DBR semiconductor laser 1. Also, the position of the light emitting point on the emission end face of the wavelength tunable DBR semiconductor laser 1 can be directly observed. Tunable DBR
This is because if the CCD camera 8 is located at a position slightly deviated from the light emitting point of the semiconductor laser 1 in the optical axis direction, the emission end face of the wavelength tunable DBR semiconductor laser 1 will be obliquely observed.

A CCD camera 8 as shown in FIG.
Is also located in the optical axis direction of the light emitted from the emission end face of the wavelength tunable DBR semiconductor laser 1, it is possible to directly observe the light emitting point position on the emission end face of the wavelength tunable DBR semiconductor laser 1. In this case, as shown in FIG.
If you install CD camera 8a and microscope lens 9a, CC
The D camera 8 detects the light emitting point position on the emission end face of the wavelength tunable DBR semiconductor laser 1, and the CCD camera 8a detects the adjustment marker 6 (see FIG. 2) on the optical waveguide type QPM-SHG device 2. Light emitting point and optical waveguide 4
(See FIG. 1).

[Third Embodiment] FIG. 10 is a plan view showing a light emitting point position detecting method according to a third embodiment of the present invention, and FIG. 11 is a side view thereof.

As shown in FIGS. 10 and 11, in the present embodiment, the semiconductor laser is positioned on the upper surface of the Si submount 7 in front of the semiconductor laser mounting portion (near the emitting end face of the wavelength tunable DBR semiconductor laser 1). A scattering surface 13 is formed. As the scattering surface 13, for example, a solder surface having a thickness of 0.5 μm can be used. If a solder surface is used, the wavelength tunable DBR
Since the semiconductor laser 1 is simultaneously melted and hardened when it is fixed, it can be used as a scatterer. Variable wavelength DB
The scattered light emitted from the R semiconductor laser 1 and scattered by the scattering surface 13 can be observed using a CCD camera located in the normal direction of the upper surface of the Si submount 7. Then, image processing is performed on the observed scattered light, and the point A4 where the light intensity is maximum is detected, whereby the light emitting point position can be detected. In this case, the light amount equal to or less than half of the light amount emitted from the wavelength tunable DBR semiconductor laser 1 is
It is desirable to be led to.

[Fourth Embodiment] FIG. 12 is a plan view showing a light emitting point position detecting method according to a fourth embodiment of the present invention, and FIG. 13 is a side view thereof.

As shown in FIGS. 12 and 13, in the present embodiment, on the upper surface of the Si submount 7, in front of the semiconductor laser mounting portion (near the emission end face of the wavelength tunable DBR semiconductor laser 1). A reflection surface 14 is formed. Here, the upper surface of the Si submount 7 is etched to
A groove is formed, and the etched surface of the V-groove is used as a reflection surface 14. As a result, of the light emitted from the wavelength tunable DBR semiconductor laser 1, the light radiated toward the Si submount 7 is etched on the V-groove (reflection surface 14).
And is guided in the normal direction of the upper surface of the Si submount 7. The reflected light guided in the direction normal to the upper surface of the Si submount 7 can be observed using a CCD camera located in the direction normal to the upper surface of the Si submount 7. Then, the reflected light is subjected to image processing to detect a point A5 at which the light intensity becomes maximum, and a point A5 between the detected point A5 and the emission end face when a perpendicular is drawn to the emission end face of the wavelength tunable DBR semiconductor laser 1. The intersection A2 is detected as a light emitting point position. Also in this case, it is desirable that an amount of light equal to or less than half of the amount of light emitted from the tunable DBR semiconductor laser 1 is guided to the reflection surface 14.

[0059]

As described above, according to the present invention,
In a coherent light source constituted by a semiconductor laser and a planar optical waveguide device, highly accurate optical coupling adjustment and mounting can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a coherent light source including a semiconductor laser and a planar optical waveguide device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the planar optical waveguide device shown in FIG.

FIG. 3 is a process chart showing a method for manufacturing a coherent light source (detection of a position of a light emitting point) according to the first embodiment of the present invention;

FIG. 4 is a process diagram showing a method of manufacturing a coherent light source (optical coupling adjustment) according to the first embodiment of the present invention.

FIG. 5 is a side view showing a light emitting point position detecting method according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a light emitting point position according to the second embodiment of the present invention.

FIG. 7 is a side view showing another example of the light emitting point position detecting method according to the second embodiment of the present invention.

FIG. 8 is a side view showing still another example of the light emitting point position detecting method according to the second embodiment of the present invention.

FIG. 9 is a side view showing a method for adjusting a position of a light emitting point and an optical waveguide according to a second embodiment of the present invention.

FIG. 10 is a plan view showing a light emitting point position detecting method according to a third embodiment of the present invention.

FIG. 11 is a side view showing a light emitting point position detecting method according to a third embodiment of the present invention.

FIG. 12 is a plan view showing a light emitting point position detecting method according to a fourth embodiment of the present invention.

FIG. 13 is a side view showing a light emitting point position detecting method according to a fourth embodiment of the present invention.

FIG. 14 is a schematic configuration diagram of an SHG blue light source using an optical waveguide type QPM-SHG device.

[Explanation of symbols]

Reference Signs List 1 wavelength tunable DBR semiconductor laser 2 optical waveguide type QPM-SHG device 3 X plate MgO-doped LiNbO ₃ substrate 4 optical waveguide 5 periodic polarization inversion region 6 adjustment marker 7 Si submount 8 CCD camera 9 microscope lens 10 collimating lens 11 Light receiving element 12 Electrode 13 Scattering surface 14 Reflecting surface

Continuation of the front page (72) Inventor Kazuhisa Yamamoto 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference) DA06 EA07 GA04 HA20 5F073 AA65 AB23 BA02 BA06 FA13

Claims (27)

[Claims] In a submount to which a semiconductor laser is fixed, a current is injected into the semiconductor laser to emit light, and the position of a light emitting point of the semiconductor laser is detected by an image detector located above the submount. A method for manufacturing a coherent light source including a step. 2. The method for manufacturing a coherent light source according to claim 1, wherein a gas serving as a scatterer is filled when detecting the position of the light emitting point of the semiconductor laser. 3. The method according to claim 1, wherein the position of the light emitting point is detected based on a point at which the light intensity of the semiconductor laser becomes maximum. 4. The method for manufacturing a coherent light source according to claim 3, wherein the position of the light emitting point is a point at which a straight line passing through the point where the light intensity becomes maximum intersects substantially perpendicularly with the emission end face of the semiconductor laser. 5. The method according to claim 1, wherein the image detector is located in a direction normal to a top surface of the submount. 6. The method for manufacturing a coherent light source according to claim 5, wherein the image detector is provided at a position inclined forward with respect to a normal passing through the light emitting point. 7. The method for manufacturing a coherent light source according to claim 5, wherein a scattering surface or a reflecting surface is formed on the submount near an emission end face of the semiconductor laser. 8. The method for manufacturing a coherent light source according to claim 7, wherein the light guided to the scattering surface or the reflection surface is equal to or less than half the amount of light emitted from the semiconductor laser. 9. The method according to claim 1, wherein the image detector is located in an optical axis direction of the semiconductor laser. 10. A method for manufacturing a coherent light source, wherein an optical waveguide device is mounted on a submount on which a semiconductor laser is fixed, wherein the optical waveguide device is based on a position of a light emitting point detected by emitting the semiconductor laser. Adjusting the relative position of the optical waveguides. 11. After adjusting the relative position of the optical waveguide, mount the optical waveguide device at a position where the optical output obtained from the emission end face of the optical waveguide device becomes substantially maximum by adjusting the optical coupling with the semiconductor laser. Claim 10
3. The method for manufacturing a coherent light source according to item 1. 12. A position adjusting direction of the light emitting point and the optical waveguide is (a) a direction perpendicular to an optical axis and parallel to the submount, and (b) a direction perpendicular to the optical axis. The method for manufacturing a coherent light source according to claim 10, wherein the direction is at least one of two directions defined in a direction perpendicular to the submount. 13. An adjusting marker is formed on the optical waveguide device at a position symmetrical in the waveguide direction with the optical waveguide as a center, and the position of the optical waveguide is determined by recognizing the adjusting marker. The method for manufacturing a coherent light source according to claim 10, wherein the detection is performed. 14. The marker for adjustment is a stripe type marker formed in parallel on both sides of the optical waveguide,
14. The method for manufacturing a coherent light source according to claim 13, wherein the position of the optical waveguide is set to the center line of the two stripe-shaped markers. 15. The method according to claim 10, wherein the optical waveguide is formed on a substrate surface of the optical waveguide device. 16. The coherent light source according to claim 10, wherein a current is injected into the semiconductor laser to emit light, and a position of a light emitting point of the semiconductor laser is detected by an image detector located above the submount. Method. 17. A gas which becomes a scatterer when detecting the position of the light emitting point of the semiconductor laser.
7. The method for manufacturing a coherent light source according to 6. 18. The method according to claim 16, wherein the position of the light emitting point is detected based on a point at which the light intensity of the semiconductor laser is maximum. 19. The method for manufacturing a coherent light source according to claim 18, wherein the position of the light-emitting point is a point at which a straight line passing through the point where the light intensity becomes maximum intersects substantially perpendicularly with the emission end face of the semiconductor laser. 20. The method according to claim 16, wherein the image detector is located in a direction normal to an upper surface of the submount. 21. The method according to claim 20, wherein the image detector is provided at a position inclined forward with respect to a normal passing through the light emitting point. 22. The method of manufacturing a coherent light source according to claim 20, wherein a scattering surface or a reflecting surface is formed on the submount near an emission end face of the semiconductor laser. 23. The method for manufacturing a coherent light source according to claim 22, wherein the light guided to the scattering surface or the reflection surface is equal to or less than half the amount of light emitted from the semiconductor laser. 24. The method for manufacturing a coherent light source according to claim 10, wherein the optical waveguide of the optical waveguide device is directly observed. 25. The method of manufacturing a coherent light source according to claim 16, wherein the image detector is located in an optical axis direction of the semiconductor laser. 26. The method for manufacturing a coherent light source according to claim 13, wherein the adjustment marker is detected by an image detector independent of the image detector. 27. An apparatus for manufacturing a coherent light source in which an optical waveguide device is mounted on a submount on which a semiconductor laser is fixed, comprising: an image detector for detecting a position of a light emitting point of the semiconductor laser; Manufacturing a coherent light source, comprising: means for adjusting the relative position of the optical waveguide of the optical waveguide device with reference to the position; and means for measuring the intensity of light emitted from the optical waveguide of the optical waveguide device. apparatus.