JP2000284135A - Optical waveguide device having planar optical waveguide, integrated optical module consisted by using the same and method to mount the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical waveguide device having a planar optical waveguide in which alignment keys for fabrication are formed with high accuracy by forming the optical waveguide and alignment keys by using one mask. SOLUTION: A Ta film is vapor deposited on a Mg-doped LiNbO3 substrate 1 and etched to form a stripe mask having openings to form a planar optical waveguide 3. At a same time, a pair of alignment keys 4 consisting of a Ta film is simultaneously formed at the positions symmetric for the center line M2 of the opening. A planar optical waveguide 3 is formed by proton exchange treatment through the opening of the mask. The Ta film is masked by a resist and removed by etching to form an additional pattern 4A. Then a SiO2 protective film 5 is formed on the surface of the substrate 1 to cover the planar optical waveguide 3, alignment keys 4 and additional pattern 4A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device (planar optical waveguide device) on which a planar optical waveguide is formed, and more particularly, an alignment key which is a mark for positioning is formed with high positional accuracy. To a planar-type optical semiconductor device. Furthermore, the present invention
The present invention relates to a configuration and a mounting method of an integrated optical module configured by mounting a planar optical waveguide device and a semiconductor laser as described above on a submount.

[0002]

2. Description of the Related Art In the field of optical communication, development of a small-sized and low-cost integrated optical module in which a semiconductor laser, an electronic element, an optical fiber, and the like are hybrid-integrated on a silica-based light-wave circuit platform is regarded as important.

[0003] In forming such an integrated optical module, it is important to fix each element with high positional accuracy and minimize the transmission loss. For this purpose, a surface mount type optical module that directly couples a semiconductor laser and a single mode fiber using a Si-V groove substrate has been realized (for example, the 1997 IEICE General Conference, C.I. -3-63).

FIG. 9 is a perspective view schematically showing a configuration of an optical module obtained by the above technique.

In this configuration, an alignment key (positioning marker) 126 having a predetermined shape (pattern) is formed in a chip mounting area 125 of a Si submount 26, and a semiconductor laser to be mounted in the chip mounting area 125 is formed. 27, an alignment key (positioning marker) 127 having a predetermined shape (pattern) is formed. The alignment keys 126 and 127 are image-recognized, and their position information is calculated by an image processing process, so that the center of the V-groove 28 formed on the Si submount 26 with high precision by Si anisotropic etching. The active layer of the semiconductor laser 27 is aligned and adjusted with high accuracy on the axis. On the other hand, an optical fiber 29 is mounted in the V-groove 28, and this mounting is performed with high accuracy by using the shapes of the V-groove 28 and the optical fiber 29, and the optical axis of the optical fiber 29 is
The alignment with the center axis of the groove 28 is adjusted with high precision.

As described above, in the configuration of FIG. 9, the optical axis of the optical fiber 29 and the light emitting point (active layer) of the semiconductor laser 27
Are adjusted with high accuracy, and the implementation variation is suppressed to about ± 0.61 μm in the x direction and about ± 1 μm in the z direction.

On the other hand, in the field of optical information processing, a compact short-wavelength light source is required in order to realize a high-density optical disc and a high-definition display. Technologies for realizing a shorter wavelength include a semiconductor laser and a quasi-phase matching (hereinafter, referred to as “QPM”) using a planar optical waveguide.
There is a method using a second harmonic generation (hereinafter, referred to as “SHG”) technique using a wavelength conversion device of the following type (eg, Yamamoto, et al .: Optics Letter).
s, Vol. 16, No. 15, p. 1156 (199
1)).

FIG. 10 is a schematic configuration diagram of a blue light source including a wavelength conversion device having a planar optical waveguide.

In the configuration shown in FIG. 10, a tunable semiconductor laser 30 having a distributed Bragg reflection (hereinafter referred to as “DBR”) region 32 is used as the semiconductor laser 30. Hereinafter, a wavelength tunable semiconductor laser having a DBR region is referred to as a “DBR semiconductor laser” or a “DBR laser”. The DBR semiconductor laser 30 is, for example, 0.1 mm.
An 85 m band 100 mW-class AlGaAs-based DBR semiconductor laser 30 comprising an active layer region 31 and a DBR region 32
It is composed of The oscillation wavelength of the DBR semiconductor laser 30 can be changed by changing the amount of injection current injected into the DBR region 32 via the wiring 39 and the bonding wire 40. On the other hand, a wavelength conversion device 33 using a planar type optical waveguide as a wavelength conversion element.
Are a planar optical waveguide 34 formed on an X-plate MgO-doped LiNbO ₃ substrate 36 and a periodically poled region 35.
And from. The DBR semiconductor laser 30 and the wavelength conversion device 33 are fixed on the submounts 37 and 38 by junction-up, respectively.
The submounts 37 and 38 are fixed on the same support member 41.

The laser light obtained from the light emitting end face of the DBR semiconductor laser 30 is directly coupled to the planar optical waveguide 34 of the wavelength conversion device 33 without using a coupling optical system such as a lens. Specifically, by adjusting the positional relationship between the DBR semiconductor laser 30 and the wavelength conversion device 33 on the submounts 37 and 38, a laser beam of about 60 mW is output for a laser output of about 100 mW from the semiconductor laser 30. Is the wavelength conversion device 3
3 is coupled to the planar optical waveguide 34. Furthermore, DBR
By controlling the amount of current injected into the DBR region 32 of the semiconductor laser 30, its oscillation wavelength is fixed within the tolerance of the phase matching wavelength of the wavelength conversion device 33. With such a configuration, blue light having a wavelength of 425 nm can be obtained with an output of about 10 mW at present.

[0011]

In an optical module in which a semiconductor laser 27 and an optical fiber 29 are integrated as shown in FIG. 9, the optical fiber 29 is mounted in a V-groove 28 formed on a Si submount 26. The semiconductor laser 27 is mounted with the V groove 28 as a reference position. The optical fiber 29 has a cylindrical shape, and its core (light propagation region) is formed at the center of the optical fiber 29. The optical fiber 29
Is also formed with a high precision controlled. Further, Si
The V-groove 28 formed on the sub-mount 26 is also formed with high precision using anisotropic etching of Si. As a result, the core, which is the center of the optical fiber 29, is mounted on the Si submount 26 with high positioning accuracy. Also, the semiconductor laser 27 can be mounted on the Si submount 26 with high positioning accuracy because the alignment keys 126 and 127 formed for the positioning are formed with reference to the V groove 28. .

On the other hand, in the wavelength conversion device 33 using the planar optical waveguide in the configuration of FIG.
_A planar (two-dimensional) planar optical waveguide 34 is formed on the _three substrates 36 by a method such as proton exchange. In the specification of the present application, a planar (two-dimensional) planar optical waveguide (a so-called “planar optical waveguide”) using a thin film or the like other than an optical waveguide device having an optical waveguide layer coaxially like an optical fiber. The optical waveguide device in which the waveguide is formed is also referred to as a “planar optical waveguide device”.

In this planar type optical waveguide device, the position of the planar type optical waveguide in the height direction from the substrate surface can be controlled with high precision at the time of formation. But,
The position of the planar optical waveguide in the lateral direction of the device is greatly affected by processes such as cutting and polishing when producing individual devices, and it is difficult to control the position with high precision. On the other hand, it is possible to mount a planar optical waveguide device by forming an alignment key or the like and detecting the position of the planar optical waveguide by the same method as that for mounting a semiconductor laser. In this case, since each of the semiconductor laser and the planar optical waveguide device is mounted on the alignment key, a mounting error increases.

In particular, in a wavelength conversion device using a planar optical waveguide and utilizing second harmonic generation (SHG), the wavelength conversion efficiency depends on the incident power of the fundamental wave to the planar optical waveguide of the wavelength conversion device. The harmonic power obtained is proportional to the square of the incident power of the fundamental wave. For this reason, in order to obtain a wavelength conversion device exhibiting excellent operating characteristics, it is essential to improve the coupling efficiency of the device to the planar optical waveguide and to reduce the variation between samples.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its objects the following objects: (1) An optical waveguide device having a planar optical waveguide in which an alignment key for mounting is formed with high precision. (2) To provide an integrated optical module configured by combining a semiconductor laser and the above-mentioned planar optical waveguide, and (3) To provide a semiconductor laser and the above-mentioned planar optical waveguide It is an object of the present invention to provide a method for mounting an integrated optical module in which an integrated optical module is configured by adjusting the position at the time of mounting with an optical waveguide device having high precision to constitute an integrated optical module.

[0016]

An optical waveguide device according to the present invention comprises: a ferroelectric substrate; a planar optical waveguide formed on the ferroelectric substrate; and a surface of the ferroelectric substrate.
At least an alignment key formed at a position separated from the planar optical waveguide by a predetermined distance, and a protective film formed on the surface of the ferroelectric substrate so as to cover the planar optical waveguide and the alignment key. And thereby achieves the objectives set forth above.

For example, the planar optical waveguide is a proton exchange planar optical waveguide formed by a proton exchange method.

Preferably, the planar optical waveguide and the alignment key are formed using the same photomask.

Preferably, the alignment key is located at a position at least 10 μm away from the planar optical waveguide.

In one embodiment, a domain-inverted region is periodically formed in the planar optical waveguide, and functions as a second harmonic generation device by quasi-phase matching.

An integrated optical module provided by the present invention has an optical waveguide device of the present invention having the above-described features, and an output light optically coupled to the planar optical waveguide of the optical waveguide device. And a semiconductor laser disposed at least in the above, whereby the above-mentioned object is achieved.

According to another aspect of the present invention, there is provided a mounting method of an integrated optical module configured by mounting at least a semiconductor laser and an optical waveguide device having a planar optical waveguide formed on a submount. You. This mounting method includes a step of detecting an edge portion of a light emitting end surface of the semiconductor laser and an edge portion of a light incident end surface of the optical waveguide device, and using the detection results of the respective edge portions to form the submount. Adjusting the positions of the semiconductor laser and the optical waveguide device in a direction substantially along a normal direction of the light emitting end face of the semiconductor laser within the surface of the semiconductor laser. Thereby, the above-mentioned object is achieved.

According to still another aspect of the present invention, there is provided a semiconductor laser having a first alignment key formed thereon, and an optical waveguide device having a planar optical waveguide formed thereon and having a second alignment key formed therein. A method for mounting an integrated optical module configured to be mounted at least on a submount is provided. The mounting method comprises the steps of: providing the first alignment key of the semiconductor laser and the second alignment key of the optical waveguide device;
Detecting the position of one of the detected first and second alignment keys within the surface of the submount as a reference position. Adjusting the position in a direction substantially parallel to the light incident end face of the optical waveguide device, thereby achieving the aforementioned object.

For example, with the position of the first alignment key as a reference position, the position of the second alignment key may be adjusted in a direction substantially parallel to the light incident end face of the optical waveguide device. . Alternatively, with the position of the second alignment key as a reference position, the position of the first alignment key may be adjusted in a direction substantially parallel to the light incident end face of the optical waveguide device.

According to still another aspect of the present invention, there is provided a method of mounting an integrated optical module, comprising: a first mounting step of mounting a semiconductor laser on which a first alignment key is formed on a submount; A second mounting step of mounting the optical waveguide device on which the optical waveguide is formed and the second alignment key is formed on the submount, wherein the second mounting step is performed on the semiconductor laser. Detecting the first alignment key and the second alignment key on the optical waveguide device, and using the detected position of the first alignment key as a reference position within the surface of the submount; Adjusting the position of the detected second alignment key in a direction substantially parallel to the light incident end face of the optical waveguide device; Detecting the edge of the light emitting end face on the laser and the edge of the light incident end face of the optical waveguide device, and utilizing the detection results of the respective edge parts, within the surface of the submount, Adjusting the positions of the semiconductor laser and the optical waveguide device in a direction substantially along the normal direction of the light emitting end face of the semiconductor laser. Achieved.

In the method for mounting an integrated optical module according to the present invention as described above, the planar optical waveguide and the second alignment key may be formed using the same photomask.

Preferably, the second alignment key is located at a position at least 10 μm away from the planar optical waveguide.

Further, for example, the planar optical waveguide may be a proton exchanged planar optical waveguide formed by a proton exchange method.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in an integrated optical module in which a semiconductor laser and an optical waveguide device having a planar optical waveguide (planar optical waveguide device) are integrated, the output from the semiconductor laser is considered. It is important to improve the coupling efficiency of the emitted light to the planar optical waveguide and to reduce the variation in the coupling efficiency between samples. In particular, an integrated optical module of a short wavelength light source using second harmonic generation (SHG) composed of a semiconductor laser and a wavelength conversion device using a planar optical waveguide as a planar optical waveguide device is obtained. Harmonic light power
2 of the incident power of the fundamental wave coupled to the planar optical waveguide
Since it is proportional to the power, improvement of coupling efficiency and reduction of variation between samples are particularly important factors.

In the following, a planar optical waveguide device in which an alignment key is formed with high precision, and an integrated optical module composed of the device and a semiconductor laser,
Several specific embodiments of the present invention will be described with respect to the configuration of an optical waveguide device that enables alignment adjustment for realizing high-precision optical coupling and a method of mounting an optical module using the configuration.

(First Embodiment) Conventionally, in order to form an alignment key, a buffer layer is formed on a planar optical waveguide and alignment is performed on the buffer layer in order to avoid the waveguide loss of the planar optical waveguide. Had formed the key.
However, in this method, since an alignment error of the photomask when forming the alignment key occurs, it is difficult to form the alignment key with high accuracy.

Therefore, in the present embodiment, in order to solve the above-mentioned problems, a planar optical waveguide in which a planar optical waveguide and an alignment key for alignment are formed on a ferroelectric substrate using the same photomask. Waveguide device 100
Will be described.

FIG. 1 is a perspective view showing the structure of a planar optical waveguide device 100 according to this embodiment.

In this configuration, the center line M2 of a substrate made of a ferroelectric material, for example, a Mg-doped LiNbO ₃ substrate 1
A planar optical waveguide 3 is formed along. A pair of alignment keys 4 made of, for example, a Ta film and a pair of additional patterns 4A are formed at positions symmetrical with respect to the planar optical waveguide 3. Further, a protective film 5 made of, for example, SiO ₂ is
It is formed on the surface of the substrate 1 so as to cover the alignment key 4 and the additional pattern 4A. However, the number of the alignment keys 4 and the number of the additional patterns 4A are not limited to one pair, but are arbitrary numbers (the number of pairs).
It is possible to form only Further, the shape of each of the alignment key 4 and the additional pattern 4A is not limited to the illustrated one, but may be any appropriate shape.

In forming the planar type optical waveguide device 100 having such a structure, first, as shown in FIG. 2, a Ta film is deposited on a Mg-doped LiNbO ₃ substrate 1, and a general Ta film is formed on the Ta film. An opening 2A (for example, about 5 μm in width) for forming the planar optical waveguide 3 by a photolithographic process and a dry etching process.
m) is formed. In this mask formation step (photolithography step and dry etching step), a pair of alignment keys 4 are simultaneously formed at positions symmetrical with respect to the center line M2 of the opening 2A.

Next, a proton exchange treatment is performed in pyrophosphoric acid (at a temperature of about 200 ° C.) through the opening 2A of the mask 2 for about 7 minutes, followed by an annealing treatment (at a temperature of about 330 ° C.). (Approximately 200 minutes) to form the planar optical waveguide 3. Thereafter, a portion corresponding to the formed position of the alignment key 4 and the pair of additional patterns 4A shown in FIG. 1 is masked with a resist, and the Ta film is removed by wet etching. By this wet etching, an additional pattern 4A is formed. And then,
The surface of the substrate 1 is covered with SiO 2 so as to cover the planar optical waveguide 3, the alignment key 4, and the additional pattern 4A.
_{2 A} protective film 5 is formed.

As described above, the planar optical waveguide device 100 having the configuration shown in FIG. 1 is manufactured.

The SiO ₂ protective film 5 is used to mount the planar optical waveguide device 100 on the submount in a junction-down manner (ie, in a direction such that the optical waveguide forming surface faces the submount) to form an integrated optical module. In this case, it is also used for adjusting the height of the planar optical waveguide 3 from the submount. That is, the film thickness of the protective film 5 (the film thickness of SiO ₂ ) is similarly mounted on the submount by junction down and coupled to the planar optical waveguide device 100 to constitute an integrated optical module. It is controlled based on the distance from the submount surface to the active layer of the semiconductor laser. In particular,
For example, in this embodiment, the protective film 5 having a thickness of about 1000 nm is used.
Are formed.

On the other hand, a mask 2, an alignment key 4, and a T formed to form an additional pattern 4 A are formed.
The film thickness of the a film (metal film) is, for example, about 100 nm.
Here, the additional pattern 4A is formed to keep the height of the planar optical waveguide 3 from the submount uniform when the planar optical waveguide device 100 is mounted on the submount in a junction-down manner. Things. If this additional pattern 4A is not formed,
When only the alignment key 4 is formed, the planar optical waveguide 3 is positioned obliquely in the longitudinal direction with respect to the submount depending on the thickness of the metal film (Ta film) constituting the alignment key 4, which is preferable. Absent. On the other hand, by forming the additional pattern 4A made of a film having the same thickness as the alignment key 4, the above problem does not occur.

When an alignment key is formed by positioning a photomask as in the prior art, the accuracy is usually about ± 0.3 μm. On the other hand, for the proton exchange planar optical waveguide 3 as in the present embodiment, the alignment key 4 can be formed using the same photomask when the Ta mask 2 for the proton exchange treatment is formed. . For this reason, since the position of the alignment key 4 can be controlled with the photomask fabrication accuracy,
As a result, a high positional accuracy can be obtained for the alignment key 4, and more specifically, the alignment key 4 can be formed with an accuracy of, for example, about ± 0.1 μm.

Further, by forming the alignment key 4 between the protective film 5 and the substrate 1, even when the planar optical waveguide device 100 is mounted on the submount in a junction-down manner when the integrated optical module is constructed. The alignment key 4 does not contact the submount. As a result, the alignment key 4 is not damaged, and a clear shape of the edge portion thereof is maintained and the image is reliably recognized, so that the practical effect is large.

As described above, in the proton exchange planar optical waveguide 3, when the Ta mask 2 is formed during proton exchange for forming the planar optical waveguide 3, the alignment key 4 is formed using the same photomask. Can be. On the other hand, in the case of the Ti-diffused planar optical waveguide, it is necessary to perform a heat treatment at 1000 ° C. or more for 6 hours in order to diffuse Ti in forming the planar optical waveguide. For this reason, when the alignment key is formed using the same photomask at the time of forming the planar optical waveguide as described above, the heat treatment for diffusing Ti deforms and deteriorates the formed Ti alignment key. Therefore, it is difficult to form an alignment key for a Ti-diffused planar optical waveguide using a photomask at the time of forming the planar optical waveguide as in the present embodiment.

As described above, the formation of the alignment key as in the present embodiment is particularly effective for a planar optical waveguide device manufactured by proton exchange, and it is possible to easily form a high-precision alignment key. it can.

In the configuration of the present embodiment, typically, the alignment key 4 is formed at a position apart from the planar optical waveguide 3, for example, at a position at least about 10 μm apart. This is for the following reason.

If the alignment key 4 is formed on or near the planar optical waveguide 3, the effective refractive index of the planar optical waveguide 3, that is, the phase state changes. Further, since the alignment key 4 is formed of a metal film (for example, a Ta film), if the alignment key 4 is too close to the planar optical waveguide 3, the waveguide loss increases.
These points are serious problems in a wavelength conversion device using a planar optical waveguide having a periodically poled structure. Therefore, to avoid such problems,
It is preferable that the alignment key 4 is formed at a position distant from the planar optical waveguide 3 and at least about 10 μm or more based on the result of the study by the present inventors.

The above point is the same for the additional pattern 4A formed from the same metal film (for example, Ta film) as the alignment key 4, for the same reason as described above.
The additional pattern 4A is preferably formed at least about 10 μm or more away from the planar optical waveguide 3.

In the following, as a more specific configuration example of the planar optical waveguide device having the features described above, a wavelength conversion device 2 using a planar optical waveguide will be described.
00 will be described.

FIG. 3 is a perspective view showing the configuration of a wavelength conversion device 200 formed according to the present embodiment.

In this configuration, the X-plate Mg-doped LiNbO
_A proton exchange planar optical waveguide 3 is formed along the center line M2 of the substrate 1. On the surface of the substrate 1, a periodically domain-inverted region 7 having a period of 3.2 μm is formed in a direction orthogonal to the proton exchange planar optical waveguide 3. A pair of alignment keys 4 made of a Ta film and a pair of additional patterns 4A are formed at positions symmetrical with respect to the planar optical waveguide 3. Further, a protective film 5 made of SiO ₂ is formed on the surface of the substrate 1 so as to cover the planar optical waveguide 3, the alignment key 4, and the additional pattern 4A.

The method of forming the alignment key 4 and the additional pattern 4A is as described above. In addition, the number of the alignment keys 4 and the number of the additional patterns 4A are not limited to one pair, but may be any number (the number of pairs). Further, their shapes are not limited to those shown, but can be set appropriately. Protective film 5 and additional pattern 4A
Are also as described above.

In the wavelength conversion device 200, the difference between the propagation speed generated between the fundamental wave incident on the planar optical waveguide 3 and the second harmonic generated by conversion of the fundamental wave is caused by the periodically poled region 7. Is compensated. Therefore, when a phase change is given to the planar optical waveguide 3, wavelength conversion characteristics are deteriorated such as a decrease in wavelength conversion efficiency and a change in a second harmonic generation curve with respect to wavelength. Here, as described above, when the alignment key is formed on or near the planar optical waveguide, the effective refractive index of the planar optical waveguide, that is, the phase state changes, as described above.

Therefore, the waveguide loss characteristics of the wavelength conversion device when three pairs of alignment keys 4 are formed close to the proton exchange planar optical waveguide 3 in the configuration of FIG. 3 were examined. As a result, alignment key 4
Is not formed, the waveguide loss of the planar optical waveguide is 0.5 dB / cm, whereas the alignment key 4 is formed close to the planar optical waveguide 3 ( Specifically, when formed at a distance of about 5 μm), the waveguide loss is 0.8 dB / cm,
An increase in waveguide loss was observed by forming the alignment key 4.

In the configuration of the wavelength conversion device 200 of the present embodiment, in order to avoid the above-described increase in the waveguide loss,
The alignment key 4 is moved from the planar optical waveguide 3 by about 10
Formed at a distance of at least μm. This is the same for the additional pattern 4A formed of the same metal film (Ta film) as the alignment key 4, and for the same reason as described above, the additional pattern 4A is a planar optical waveguide. It is preferable to form them at a distance of about 10 μm or more from 3.

On the other hand, FIG. 4 shows periodic polarization inversion regions included in a wavelength conversion device using a planar optical waveguide.
Further, by providing a phase change portion, the vicinity of the top of the second harmonic generation curve with respect to the wavelength is flattened, and the wavelength tolerance for wavelength conversion is expanded (for example, an optical letter, Vol.23, N
o. 24 pp. 1880-1882, 1998). As described above, in the case where the characteristics of the second harmonic generation curve are adjusted by installing the phase change portion, if the phase change or the change of the waveguide loss is given, the effect on the second harmonic generation curve is not affected. growing. For example, FIG. 5 shows a configuration of a wavelength conversion device using a planar optical waveguide having the characteristics shown in FIG. 4 (a configuration in which a phase change portion is further provided in a periodically poled region).
The second harmonic generation curve obtained when an alignment key is further formed at a position apart by μm is shown. In this case, the flat portion near the top of the curve is inclined compared to the characteristics in FIG. 4, and the characteristics are degraded. On the other hand, if the alignment key is formed at a position at least 10 μm away from the planar optical waveguide, a second harmonic generation curve similar to that in FIG. 4 is observed, and no characteristic deterioration is observed.

As in the present embodiment, in the wavelength conversion device using the planar optical waveguide, the alignment key
Is formed, it is possible to reduce the influence on the waveguide loss and the phase state of the planar optical waveguide 3 due to the installation of the alignment key 4. In particular, in the wavelength conversion device using the second harmonic generation of the quasi-phase matching method, a decrease in the wavelength conversion efficiency and the deterioration of the second harmonic generation curve can be reduced by the above, and the practical effect is large.

Further, in this embodiment, since the additional pattern 4A made of a film having the same thickness as the alignment key 4 is formed on both sides of the planar optical waveguide 3, the wavelength conversion using the planar optical waveguide is performed. Even if the device is mounted on the submount in a junction-down manner, the height of the planar optical waveguide 3 from the submount is kept uniform, and stable optical coupling characteristics are realized.

(Second Embodiment) In the present embodiment, in an integrated optical module 300 in which a semiconductor laser and a planar optical waveguide device are integrated on a submount, each of the semiconductor laser and the planar optical waveguide device A mounting method for realizing highly efficient optical coupling between the semiconductor laser and the planar optical waveguide device by recognizing the alignment keys formed on the semiconductor laser and adjusting the positional relationship between the alignment keys will be described.

FIGS. 6A and 6B are a side view and a plan view showing the configuration of the integrated optical module 300 constructed according to the present embodiment.

In the optical module 300 of this embodiment, S
The semiconductor laser 11 and the planar optical waveguide device are mounted on the i-submount 13. As the planar optical waveguide device, the periodically poled region (not shown in FIG. 6) and the proton exchange planar optical waveguide 3 are formed on the Mg-doped LiNbO ₃ substrate 1 described in the first embodiment. The wavelength conversion device 200 is used. On the substrate 1 of the wavelength conversion device 200, the alignment key 4 is formed at a position 10 μm away from the planar optical waveguide 3 by the method described in the first embodiment. On both sides of the planar optical waveguide 3, additional patterns 4A are formed by a film (for example, a Ta film) having the same material and thickness as the alignment key 4. After the formation of the alignment key 4 and the additional pattern 4A, in order to adjust the position of the planar optical waveguide 3 and the laser emitting portion 19 of the semiconductor laser 11 at the time of junction down mounting in the height direction,
The SiO ₂ protective film 5 is formed in the same manner as in the first embodiment. Further, a metal film 21 made of, for example, Ta is deposited on the protective film 5. Then, by fixing the Ta metal film 21 to the solder layer 15 deposited on the Si submount 13 via the metal film 14 functioning as an electrode, the wavelength conversion device 200 is fixed to the Si submount 13.

On the other hand, an electrode 23 and an alignment key 17 are also formed on the surface of the semiconductor laser 11. Si
The semiconductor laser 11 is fixed to the Si submount 13 by fixing the electrode 23 to the solder layer 15 deposited on the submount 13 via the metal film 14.

When the semiconductor laser 11 is a DBR semiconductor laser, the electrode 23 of the semiconductor laser 11 and the metal film 14 and the solder layer 15 formed on the Si submount 13 corresponding to the semiconductor laser 11 are formed. The semiconductor laser 11 is divided and provided for each of the active layer region and the DBR region (not shown) of the semiconductor laser 11 as shown. Alternatively, when the semiconductor laser 11 is a general semiconductor laser that is not a DBR type, it is necessary to provide the electrode 23, the metal film 14, and the solder layer 15 separately as shown in FIG. There is no.

In FIG. 6B, for convenience, the alignment key 17 formed on the submount surface of the semiconductor laser 11 and the alignment key 17 formed on the submount surface of the wavelength conversion device 200 are shown. The positions of the key 4, the additional pattern 4A and the planar optical waveguide 3 are depicted in the figure.

Semiconductor laser 11 and wavelength conversion device 2
No. 00 is the junction sub-mount 1 so that the active layer (junction) surface or the planar optical waveguide forming surface is in contact with the Si sub-mount 13.
3 is implemented. When mounting the semiconductor laser 11
And the wavelength conversion device 200 are held by separate chip hands 161 and 162, respectively, so as to be parallel to the Si submount 13. Note that the position of the laser light emitting portion 19 of the semiconductor laser 11 and the position of the planar optical waveguide 3 of the wavelength conversion device 200 using the planar optical waveguide are respectively determined by the Si submount 13 after mounting.
Is adjusted so as to have a height of 10 μm from the surface.

A detection device 136 used for image recognition of the alignment keys 4 and 17 at the time of mounting includes a halogen lamp that emits infrared light, an infrared camera for detecting infrared light, and a detected image. Includes a computer for processing. Specifically, the infrared light of the halogen lamp is irradiated from the back surface of the Si submount 13 and the alignment key 1 formed on the semiconductor laser 11 is irradiated by the infrared light camera.
7, and the alignment key 4 formed on the wavelength conversion device 200 are detected. Alignment key 17 on semiconductor laser 11 and wavelength conversion device 200
And 4 are portions where light is guided (laser emitting portion 1).
9 and the planar optical waveguide 3). Therefore, the images of the alignment keys 17 and 4 detected by the infrared light camera of the detection device 136 are image-processed by a computer, and the center lines M1 and M2 of the respective alignment keys 17 and 4 are obtained.

Referring to FIGS. 11A and 11B, the process of calculating the center lines M1 and M2 of the alignment keys 17 and 4 will be described in detail. FIGS. 11 (a) and (b)
FIG. 4 is a diagram schematically illustrating recognition images of alignment keys 17 and 4 on a semiconductor laser 11 and a wavelength conversion device 200 obtained by a detection device 136, respectively. Each of the alignment keys 17 and 4 is actually composed of two pairs of keys. Here, they are referred to as 17-1 and 17-2, and 4-1 and 4-
Referenced as 2.

First, the alignment keys 17-1 and 17-2 on the semiconductor laser 11 shown in FIG.
Are determined by computer image processing based on the recognized images. Next, the center line M1 of the calculated centroids A1 and A2 is obtained. Similarly, FIG.
The center of gravity B1 and B2 of each alignment key 4-1 and 4-2 on the wavelength conversion device 200 shown in FIG.
Is obtained by image processing on a computer based on the recognized image. Next, the center line M2 of the calculated centroids B1 and B2 is obtained. At the time of actual processing, 4
Four alignment keys 17-1 and 17-2 and 4-
1 and 4-2 are recognized. First, only one side of the screen is image-processed, and then only the other side of the screen is image-processed, whereby the respective center lines M1 and M2 are recognized.

In the configuration after mounting the optical module 300 in the present embodiment, the laser light emitting section 1 of the semiconductor laser 11
Conversion device 2 using an optical waveguide 9 and a planar optical waveguide
The planar optical waveguides No. 00 are adjusted so as to be located at a height of 10 μm from the Si submount 13 respectively. On the other hand, when the center line M1 of the semiconductor laser 11 is calculated, the wavelength conversion device 200 is intentionally held at a height different from that of the semiconductor laser 11, for example, at a height of 50 μm from the Si submount 13.
Only the alignment keys 17-1 and 17-2 on the semiconductor laser 11 are detected.

As described above, the respective center lines M1 and M
Is obtained, the center line M2 of the wavelength conversion device 200 is then used as a reference, and the center line M2
The position of the semiconductor laser 11 is adjusted in a direction parallel to the light incident end face of the wavelength conversion device 200 (in this case, a direction perpendicular to the light propagation direction) so that 1 coincides.
The center line M1 of the semiconductor laser may be used as a reference and the center line M2 of the wavelength conversion device 200 may be adjusted with respect to the center line M1, but the semiconductor laser 11 is smaller than the wavelength conversion device 200 and Since it is light, it is better to adjust the alignment by moving the semiconductor laser 11,
desirable.

Next, based on the detection results of the edge of the light emitting end face of the semiconductor laser 11 and the edge of the light incident end face of the wavelength conversion device 200, the distance between the end faces is set to 3 μm. The position in the direction along the normal direction of the light emitting end face of the laser 11 (in this case, the light propagation direction) is adjusted. When the distance between the semiconductor laser 11 and the wavelength conversion device 200 is 10 μm, when compared with the case where the distance is 0 μm (that is, when the semiconductor laser 11 and the wavelength conversion device 200 are in direct contact), The coupling efficiency between the two is reduced by half. But,
On the other hand, the semiconductor laser 11 and the wavelength conversion device 20
If 0 is too close, the end face of the semiconductor laser 11 may be destroyed. Therefore, in the present embodiment, the distance between the semiconductor laser 11 and the wavelength conversion device 200 (between the light emitting end face and the light incident end face) is set to 3 μm.

When the alignment is completed as described above, the semiconductor laser 11 and the wavelength conversion device 200 are respectively mounted on the Si submount 13, and the Si submount 13 is heated to 300 ° C. 15 is melted. Subsequently, the solder is cooled while flowing N ₂ gas to avoid oxidation of the solder, and the solder is solidified again. Thereby, the semiconductor laser 11 and the wavelength conversion device 200
Is fixed on the Si submount 13.

In the configuration of the integrated optical module 300 of this embodiment, the laser light obtained from the light emitting end face of the semiconductor laser 11 is coupled to the planar optical waveguide 3 of the wavelength conversion device 200. Specifically, for a laser output of 100 mW from the semiconductor laser 11, a laser beam of 50 mW was coupled to the planar optical waveguide 3 of the wavelength conversion device 200 (coupling efficiency 50%). By fixing the oscillation wavelength of the semiconductor laser 11 within the tolerance of the phase matching wavelength of the wavelength conversion device 200, harmonic light having a wavelength of 425 nm was obtained at about 5 mW, and highly efficient optical coupling and wavelength conversion were realized.

In the present invention, no alignment key for positioning is formed on the Si submount 13. This is because, when the alignment is adjusted with respect to the alignment key on the Si submount 13 as in the related art, an error occurs at the time of each mounting, and as a result, a mounting error increases. For example, when an alignment key is provided on the Si submount 13 according to the related art and the alignment is adjusted with respect to the alignment key, the positional accuracy at the time of mounting is about ± 0.6 μm. On the other hand, if the alignment key 17 of the semiconductor laser 11 is aligned and adjusted with respect to the alignment key 4 on the wavelength conversion device 200 as in the present embodiment, the relative positional relationship between them is directly adjusted. As a result, high-precision alignment adjustment was possible, and the mounting was typically achieved with an alignment adjustment accuracy of about ± 0.3 μm or less. In the optical coupling characteristics between the semiconductor laser and the wavelength conversion device, the alignment adjustment accuracy at which the optical coupling efficiency is halved is generally about ± 0.5 μm.
By realizing the alignment adjustment accuracy of 0.3 μm or less, 9
With a sample of 0% or more, a coupling efficiency of 45% or more is obtained. In addition, since mounting can be performed by a single alignment adjustment, the time required for mounting is short. Therefore, the alignment adjustment and mounting method of the present embodiment is a practical method suitable for mass productivity, and has a great effect.

In the present embodiment, since the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200 can be directly adjusted, the accuracy of alignment adjustment and mounting depends on errors in the production of the alignment keys 17 and 4. . As described in relation to the first embodiment, in the proton exchange planar optical waveguide 3, the alignment key 4 is formed using the same photomask when the Ta mask is formed at the time of proton exchange for forming the planar optical waveguide. can do. On the other hand, in the case of the Ti-diffused planar optical waveguide, it is necessary to perform a heat treatment at 1000 ° C. or more for 6 hours in order to diffuse Ti in forming the planar optical waveguide. For this reason, if the alignment key is formed using the same photomask when forming the planar optical waveguide as described above,
The heat treatment for diffusing Ti deforms and deteriorates the formed alignment key of Ti. Therefore, it is difficult to form an alignment key for a Ti-diffused planar optical waveguide using a photomask at the time of forming the planar optical waveguide as in the present embodiment. Thus, in the method for adjusting the alignment of the integrated optical module of the present embodiment, it is easier to form a highly accurate alignment key in the case of the planar optical waveguide device manufactured by proton exchange, and it is possible to obtain a highly accurate alignment key. Positioning adjustment and mounting become possible, which is more effective.

In the above description of the present embodiment, the configuration using the wavelength conversion device 200 using the planar optical waveguide described in the first embodiment as an example is described. According to the present embodiment, by directly adjusting the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200 using the planar optical waveguide,
High-precision alignment adjustment is possible, and highly efficient optical coupling between the two can be realized. In particular, in the integrated optical module of the short wavelength light source using the second harmonic generation (SHG) composed of the semiconductor laser and the wavelength conversion device using the planar type optical waveguide, the obtained harmonic light power is
2 of the incident power of the fundamental wave coupled to the planar optical waveguide
Since it is proportional to the power, improvement of coupling efficiency is a particularly important factor. Therefore, the method for adjusting the alignment of the integrated optical module according to the present embodiment is particularly effective for a planar optical waveguide device that is a second harmonic generation device.

In the present embodiment, a heating process for melting the solder layer 15 is performed at the time of mounting and fixing to the Si submount 13.
0 is heated to 300 ° C., and the proton exchange planar optical waveguide 3 is annealed. Therefore, the wavelength conversion device 200 is designed and formed in consideration of the annealing effect on the proton exchange planar optical waveguide 3 in advance. Thus, even if the semiconductor laser 11 and the wavelength conversion device 200 are mounted and fixed on the Si submount 13 by heating and melting the solder layer 15, highly efficient wavelength conversion characteristics can be obtained.

(Third Embodiment) In this embodiment, in an optical module 400 in which a semiconductor laser and a planar optical waveguide device are integrated, an alignment key formed on each of the semiconductor laser and the planar optical waveguide device is provided. From the device side, and by adjusting the positional relationship of each alignment key, the semiconductor laser and the planar optical waveguide device are mounted on the AlN submount having higher thermal conductivity than Si with high accuracy. A method of mounting an optical module for realizing highly efficient optical coupling between the two will be described. In this embodiment, by using a submount made of a material having high thermal conductivity (AlN), the life of the semiconductor laser can be prolonged, and the distortion of the submount resulting from heat distribution can be reduced.

FIGS. 7A and 7B are a side view and a plan view showing the configuration of an integrated optical module 400 constructed according to the present embodiment.

In the optical module 300 of this embodiment, A
The semiconductor laser 11 and the planar optical waveguide device are mounted on the 1N submount 24. As the planar optical waveguide device, the periodically poled region (not shown in FIG. 7) and the proton exchange planar optical waveguide 3 are formed on the Mg-doped LiNbO ₃ substrate 1 described in the first embodiment. The wavelength conversion device 200 is used. On the substrate 1 of the wavelength conversion device 200, the alignment key 4 is formed at a position 10 μm away from the planar optical waveguide 3 by the method described in the first embodiment. On both sides of the planar optical waveguide 3, additional patterns 4A are formed by a film (for example, a Ta film) having the same material and thickness as the alignment key 4. After the formation of the alignment key 4 and the additional pattern 4A, the SiO ₂ protective film 5 is used to adjust the alignment between the planar optical waveguide 3 and the laser emitting portion 19 of the semiconductor laser 11 in the height direction. It is formed similarly to the first embodiment. Further, a metal film 21 made of, for example, Ta is deposited on the protective film 5. And
The Ta metal film 2 is formed on the solder layer 15 deposited on the AlN submount 24 via the metal film 14 functioning as an electrode.
1 is fixed, the wavelength conversion device 200 becomes AlN
It is fixed to the submount 24.

On the other hand, an electrode 23 and an alignment key 17 are also formed on the surface of the semiconductor laser 11. Al
The semiconductor laser 11 is fixed to the AlN submount 24 by fixing the electrode 23 to the solder layer 15 deposited on the N submount 24 via the metal film 14.

When the semiconductor laser 11 is a DBR semiconductor laser, the electrode 23 of the semiconductor laser 11 and the metal film 14 and the solder layer 15 formed on the AlN submount 24 corresponding to the semiconductor laser 11 are The semiconductor laser 11 is divided and provided for each of the active layer region and the DBR region (not shown) of the semiconductor laser 11 as shown. Alternatively, when the semiconductor laser 11 is a general semiconductor laser that is not a DBR type, it is necessary to provide the electrode 23, the metal film 14, and the solder layer 15 separately as shown in FIG. There is no.

In FIG. 7B, for convenience, the alignment key 17 formed on the submount side surface of the semiconductor laser 11 and the alignment key 17 formed on the submount side surface of the wavelength conversion device 200 are shown for convenience. The positions of the key 4, the additional pattern 4A and the planar optical waveguide 3 are depicted in the figure.

Semiconductor laser 11 and wavelength conversion device 2
No. 00 is mounted on the AlN submount 24 by junction down so that the active layer (junction) surface or the planar optical waveguide forming surface is in contact with the AlN submount 24. In mounting, the semiconductor laser 11 and the wavelength conversion device 200 are separated from each other by the chip hands 161 and 162, respectively.
Is held parallel to. In addition, the position of the laser light emitting portion 19 of the semiconductor laser 11 and the position of the planar optical waveguide 3 of the wavelength conversion device 200 using the planar optical waveguide are each set at a height of 10 μm from the surface of the Si submount 13 after mounting. It has been adjusted to be.

A detection device 136 used for image recognition of the alignment keys 4 and 17 at the time of mounting includes a halogen lamp that emits infrared light, an infrared camera for detecting infrared light, and a detected image. Includes a computer for processing. Specifically, in the configuration of the optical module of the present embodiment, since the AlN submount 24 does not transmit infrared light, the submount 24 is irradiated with infrared light from a halogen lamp from the device mounting surface side, The optical camera detects an alignment key 17 formed on the semiconductor laser 11 and an alignment key 4 formed on the wavelength conversion device 200, respectively. Alignment keys 17 and 4 on semiconductor laser 11 and wavelength conversion device 200
Are formed at centrally symmetric positions with respect to the portions where the light is guided (the laser light emitting portion 19 and the planar optical waveguide 3). Therefore, FIG.
According to the method described with reference to (a) and (b),
The images of the alignment keys 17 and 4 detected by the infrared light camera of the detection device 136 are image-processed by a computer, and the center line M of each of the alignment keys 17 and 4 is processed.
1 and M2 are obtained.

After the respective center lines M1 and M2 have been obtained, the light incident on the wavelength conversion device 200 is next set so that the center line M1 of the semiconductor laser coincides with the center line M2 of the wavelength conversion device 200. The position of the semiconductor laser 11 is adjusted in a direction parallel to the end face (in this case, a direction perpendicular to the light propagation direction). The center line M1 of the semiconductor laser may be used as a reference and the center line M2 of the wavelength conversion device 200 may be adjusted with respect to the center line M1, but the semiconductor laser 11 is smaller than the wavelength conversion device 200 and Because it is light, semiconductor laser 1
It is more desirable to adjust the alignment by moving the position 1.

Next, as in the second embodiment,
The distance between the edge of the light emitting end face of the semiconductor laser 11 and the edge of the light incident end face of the wavelength conversion device 200 is 3
The position of both is adjusted in the direction along the normal direction of the light emitting end face of the semiconductor laser 11 (in this case, the light propagation direction) so as to be μm. When the alignment is completed, the semiconductor laser 11 and the wavelength conversion device 200 are respectively set to Al
Placed on the N submount 24, the AlN submount 24 is heated to 300 ° C. and the solder layer 15 is melted. Subsequently, cooling is performed while flowing N ₂ gas to avoid oxidation of the solder, and the solder is solidified again. Thus, the semiconductor laser 11 and the wavelength conversion device 200 are fixed on the AlN submount 24.

In the configuration of the integrated optical module 400 of this embodiment, the laser light obtained from the light emitting end face of the semiconductor laser 11 is coupled to the planar optical waveguide 3 of the wavelength conversion device 200. Specifically, for a laser output of 100 mW from the semiconductor laser 11, a laser beam of 50 mW was coupled to the planar optical waveguide 3 of the wavelength conversion device 200 (coupling efficiency 50%). By fixing the oscillation wavelength of the semiconductor laser 11 within the tolerance of the phase matching wavelength of the wavelength conversion device 200, harmonic light having a wavelength of 425 nm was obtained at about 5 mW, and highly efficient optical coupling and wavelength conversion were realized. Also, the AlN submount 24 has a high thermal conductivity, and its thermal expansion coefficient is close to that of GaAs typically used as a constituent material of a semiconductor laser substrate. On the other hand, more stable optical coupling is obtained than with the Si submount. Specifically, for a temperature change of about ± 20 ° C., the variation of the coupling efficiency was about ± 5% or less.

In this embodiment, similarly to the second embodiment, no alignment key is formed on the AlN submount 24 for positioning. This is the second
This is because, as described in connection with the embodiment, when the alignment adjustment is performed on the alignment key on the submount, an error occurs at the time of each mounting, and as a result, a mounting error increases. According to the present embodiment, high-precision alignment adjustment can be performed by directly adjusting the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200. In addition, since mounting can be performed by a single alignment adjustment, the time required for mounting is short. Therefore, the alignment adjustment and mounting method of the present embodiment is a practical method suitable for mass productivity, and has a great effect.

In this embodiment, as in the second embodiment, the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200 can be directly adjusted. 4 depends on the error at the time of fabrication. As described above, in the proton-exchanged planar optical waveguide 3, the alignment key 4 can be formed with high precision using the same photomask when forming the Ta mask at the time of proton exchange for forming the planar-type optical waveguide. Accordingly, in the method for adjusting the alignment of the integrated optical module according to the present embodiment, it is easier to form the alignment key with higher accuracy in the planar-type optical waveguide device manufactured by proton exchange, and the alignment with higher accuracy is achieved. Adjustment and implementation are possible, which is more effective.

In the above description of the present embodiment, the configuration using the wavelength conversion device 200 using the planar optical waveguide described in the first embodiment is described as an example. According to the present embodiment, high-precision alignment adjustment is possible by directly adjusting the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200, and highly efficient optical coupling between the two can be realized. . In particular, the second harmonic generation (SH) composed of a semiconductor laser and a wavelength conversion device using a planar optical waveguide
In the integrated optical module of short wavelength light source using G),
Since the obtained harmonic light power is proportional to the square of the incident power of the fundamental wave coupled to the planar optical waveguide, improvement of coupling efficiency is a particularly important factor. Therefore, the method for adjusting the alignment of the integrated optical module according to the present embodiment is particularly effective for a planar optical waveguide device that is a second harmonic generation device.

In this embodiment, when the semiconductor device is mounted and fixed on the AlN submount 24, a heat treatment for melting the solder layer 15 is performed.
00 is heated to 300 ° C., and the proton exchange planar optical waveguide 3 is annealed. Therefore, the wavelength conversion device 200 is designed and formed in consideration of the annealing effect on the proton exchange planar optical waveguide 3 in advance. Thus, even if the semiconductor laser 11 and the wavelength conversion device 200 are mounted and fixed on the AlN submount 24 by heating and melting the solder layer 15, highly efficient wavelength conversion characteristics can be obtained.

(Fourth Embodiment) In this embodiment, in an optical module 500 in which a semiconductor laser and a planar optical waveguide device are integrated, an alignment key formed on each of the semiconductor laser and the planar optical waveguide device is provided. A method of realizing highly efficient optical coupling between the semiconductor laser and the planar optical waveguide device by recognizing the above and adjusting the positional relationship between the alignment keys will be described.

FIGS. 8A to 8E are diagrams illustrating each step of the mounting method of the integrated optical module 500 in the present embodiment.

In the optical module 500 of this embodiment, S
The semiconductor laser 11 and the planar optical waveguide device are mounted on the i-submount 13. As the planar optical waveguide device, the periodic domain-inverted region (not shown in FIG. 8) and the proton exchange planar optical waveguide 3 are formed on the Mg-doped LiNbO ₃ substrate 1 described in the first embodiment. The wavelength conversion device 200 is used. On the substrate 1 of the wavelength conversion device 200, the alignment key 4 is formed at a position 10 μm away from the planar optical waveguide 3 by the method described in the first embodiment. On both sides of the planar optical waveguide 3, additional patterns 4A are formed by a film (for example, a Ta film) having the same material and thickness as the alignment key 4. After the formation of the alignment key 4 and the additional pattern 4A, the SiO ₂ protective film 5 is used to adjust the alignment between the planar optical waveguide 3 and the laser emitting portion 19 of the semiconductor laser 11 in the height direction. It is formed similarly to the first embodiment. In the present embodiment, the wavelength conversion device 200 having such a configuration is the metal film 1 functioning as an electrode formed on the Si submount 13.
4 is fixed by an ultraviolet curable resin (UV curable resin).

On the other hand, an electrode 23 and an alignment key 17 are formed on the surface of the semiconductor laser 11 by, for example, an Au film.
Are formed. At a position corresponding to the mounting position of the semiconductor laser 11 on the Si submount 13, a solder layer 15 is formed on a metal film 14 functioning as an electrode, and the electrode 23 is fixed to the solder layer 15. Thus, the semiconductor laser 11 is fixed to the Si submount 13.

When the semiconductor laser 11 is a DBR semiconductor laser, the electrode 23 of the semiconductor laser 11 and the metal film 14 and the solder layer 15 formed on the Si submount 13 corresponding to the semiconductor laser 11 are formed. The semiconductor laser 11 is divided and provided for each of the active layer region and the DBR region (not shown) of the semiconductor laser 11 as shown. Alternatively, when the semiconductor laser 11 is a general semiconductor laser that is not a DBR type, it is necessary to provide the electrode 23, the metal film 14, and the solder layer 15 separately as shown in FIG. There is no.

Subsequently, referring to FIGS. 8A to 8E,
The mounting method of the optical module 500 in the present embodiment
I will explain again.

In this embodiment, the semiconductor laser 11
The wavelength conversion device 200 and the wavelength conversion device 200 are mounted on the Si submount 13 by junction down so that the active layer (junction) surface or the planar optical waveguide forming surface is in contact with the Si submount 13. At the time of mounting, first, as shown in FIG. 8A, the semiconductor laser 11 and the wavelength conversion device 200 are held by separate chip hands 161 and 162, respectively, so as to be parallel to the Si submount 13. It is located above each mounting location on the submount 13. Next, after placing the semiconductor laser 11 on the solder layer 15 of the Si submount 13, the Si submount 13 is heated to 300 ° C. to melt the solder layer 15. Subsequently, in order to avoid oxidation of the solder, cooling is performed while flowing N ₂ gas to solidify the solder again, and as shown in FIG.
1 is fixed on the Si submount 13.

Next, using the alignment key 17 formed on the semiconductor laser 11, the wavelength conversion device 2
00 alignment adjustment, and the Si submount 13
The planar optical waveguide surface is on the Si submount 13
Implement to touch.

Specifically, first, as shown in FIG. 8C, the wavelength conversion device 200 is held by the chip hand 162, and the position is adjusted so as to be parallel to the Si submount 13.

Next, a halogen lamp (not shown) emitting infrared light is irradiated from the back surface of the Si submount 13 to the semiconductor laser 11 and the wavelength conversion device 200 by an infrared camera (not shown). The formed alignment keys 17 and 4 are detected. Then, the center of gravity of the alignment key 17 is first determined by image processing by a computer based on the detected image, and the center line M1 of the alignment key 17 is determined based on the center of gravity. Then, similarly,
The center of gravity of each alignment key 4 on the wavelength conversion device 200 is obtained, and the center line M2 thereof is further obtained. At the time of actual processing, both alignment keys 17 and 4 are recognized on one screen. First, only one side of the screen is image-processed.
Next, image processing is performed only on the other side of the screen, whereby the respective center lines M1 and M2 are recognized.

Semiconductor laser 11 and wavelength conversion device 2
Alignment keys 17 and 4 above 00 are formed at centrally symmetrical positions with respect to the portions where light is guided (laser light emitting portion 19 and planar optical waveguide 3). After the respective center lines M1 and M2 are obtained as described above, the wavelength conversion device 200 is next set such that the center line M2 of the wavelength conversion device 200 matches the center line M1 of the semiconductor laser 11. In the direction perpendicular to the light propagation direction, that is, the wavelength conversion device 200.
8 (in the direction of arrow 62 in FIG. 8D).

Next, as in the second embodiment,
Light emitting end face of semiconductor laser 11 and wavelength conversion device 20
The light propagation direction based on the detection result of each edge portion, that is, the direction along the normal direction of the light emitting end face of the semiconductor laser 11 (FIG. 8) so that the distance from the light incident end face of the semiconductor laser 11 becomes 3 μm. Position adjustment in the direction of the arrow 64 in (d)) is performed. When the alignment is completed, a UV curable resin is applied between the wavelength conversion device 200 and the Si submount 13 by a dispenser (not shown), and further, irradiation of UV light is performed to cure the applied resin. As a result, as shown in FIG.
0 is fixed on the Si submount 13 to configure the optical module 500.

In the configuration of the integrated optical module 500 of this embodiment, the laser light obtained from the light emitting end face of the semiconductor laser 11 is coupled to the planar optical waveguide 3 of the wavelength conversion device 200. Specifically, for a laser output of 100 mW from the semiconductor laser 11, a laser beam of 50 mW was coupled to the planar optical waveguide 3 of the wavelength conversion device 200 (coupling efficiency 50%). Further, similarly to the second embodiment, a positioning adjustment accuracy of about ± 0.3 μm or less is realized, and as a result, a coupling efficiency of 45% or more is obtained for a sample of 90% or more. By fixing the oscillation wavelength of the semiconductor laser 11 within the tolerance of the phase matching wavelength of the wavelength conversion device 200, harmonic light having a wavelength of 425 nm was obtained at about 5 mW, and highly efficient optical coupling and wavelength conversion were realized. Further, in the present embodiment, since the wavelength conversion device 200 is mounted without heat treatment, more efficient wavelength conversion characteristics are realized.

In the present embodiment, similarly to the second embodiment, no alignment key for positioning is formed on the Si submount 13. As described in relation to the second embodiment, if the alignment is adjusted with respect to the alignment key on the submount, an error occurs at the time of each mounting, and as a result, a mounting error increases. . According to the present embodiment, the semiconductor laser 1
By directly adjusting the positional relationship between the device 1 and the wavelength conversion device 200, highly accurate alignment adjustment can be performed. In addition, since mounting can be performed by a single alignment adjustment, the time required for mounting is short. Therefore, the alignment adjustment and mounting method of the present embodiment is a practical method suitable for mass productivity, and has a great effect.

In the present embodiment, as in the second embodiment, the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200 can be directly adjusted. 4 depends on the error at the time of fabrication. As described above, in the proton-exchanged planar optical waveguide 3, the alignment key 4 can be formed with high precision using the same photomask when forming the Ta mask at the time of proton exchange for forming the planar-type optical waveguide. As a result, in the method for adjusting the alignment of the integrated optical module of the present embodiment, it is easier to form a highly accurate alignment key in the planar optical waveguide device manufactured by proton exchange, and to achieve a highly accurate alignment. Adjustment and implementation are possible, which is more effective.

In the above description of the present embodiment, the configuration using the wavelength conversion device 200 using the planar optical waveguide described in the first embodiment as an example of the wavelength conversion device has been described. According to the present embodiment, high-precision alignment adjustment is possible by directly adjusting the positional relationship between the semiconductor laser 11 and the wavelength conversion device 200, and highly efficient optical coupling between the two can be realized. . In particular, in an integrated optical module of a short wavelength light source using second harmonic generation (SHG) composed of a semiconductor laser and a wavelength conversion device, the obtained harmonic light power is applied to the fundamental wave coupled to the planar optical waveguide. , Is proportional to the square of the incident power, so that the coupling efficiency is a particularly important factor. Therefore, the method for adjusting the alignment of the integrated optical module according to the present embodiment is particularly effective for a planar optical waveguide device that is a second harmonic generation device.

In this embodiment, the wavelength conversion device 200
Is fixed with a UV curable resin, so that it can be mounted without performing a heat treatment. As a result, since the mounting can be performed without considering the change in the operation characteristics, the effect is large.

When the integrated optical module of the present invention is used as a light source or the like in an optical disk device, it is required to align a light emitting point of a semiconductor laser with a positional accuracy of about 100 μm. In that case, apart from the alignment key according to the present invention, a conventional general alignment key is formed on the semiconductor laser and the submount, and the semiconductor laser is mounted on the submount using these. Then, even if the wavelength conversion device 200 is aligned and mounted on the mounted semiconductor laser 11 so that the center lines M1 and M2 coincide with each other according to the method of the present embodiment, the same effect can be obtained. can get.

In the description of each of the above embodiments, the light incidence end face of the planar optical waveguide device included in the integrated optical module is formed perpendicular to the planar optical waveguide. However, the application of the present invention is not limited to such a case, and even in mounting an integrated optical module using a planar optical waveguide device whose end face is formed obliquely with respect to the planar optical waveguide, The present invention can provide the same effect.

FIG. 12 schematically shows an example of the configuration of an integrated optical module using a planar optical waveguide device having an oblique end face.

In this integrated optical module, the semiconductor laser 50 and the optical waveguide device 51 having the planar optical waveguide 52 are mounted on the submount 53 by the light emitting end face of the semiconductor laser 50 and the light incident on the optical waveguide device 51. It is mounted so that it faces the end face. Here, the end face of the optical waveguide device 51 is formed to be inclined about 4 degrees from a direction orthogonal to the optical waveguide 52. In this case, the optical waveguide device 51 is made of a LiNbO ₃ substrate (refractive index = about 2.
1), the angle of incidence of light on the optical waveguide 52 is approximately 8.4 degrees according to Snell's law (ie, the optical axis of the optical waveguide 52 is
Is inclined by about 8.4 degrees with respect to the optical axis of the outgoing light.
Therefore, the optical axis of the semiconductor laser 50 and the light propagation direction in the optical waveguide 52 of the optical waveguide device 51 are not parallel to each other.

Even in such a case, in order to perform the optical coupling adjustment while keeping the distance between the light emitting end face of the semiconductor laser 50 and the light incident end face of the optical waveguide device 51 constant, the above-described embodiment is used. In accordance with the method according to the present invention described above, the alignment adjustment is performed by moving the optical waveguide device 51 in the direction indicated by the arrow 72 in FIG. 12, that is, in the direction parallel to the light incident end face of the optical waveguide device 51.

The alignment adjustment in the direction indicated by the arrow 74 in FIG. 12, that is, the direction along the normal direction of the light emitting end face of the semiconductor laser 50 is performed as described in the previous embodiments. This can be performed based on the detection results of the edge portion of the light emitting end surface of the optical waveguide device 50 and the edge portion of the light incident end surface of the optical waveguide device 51.

In the above description of each embodiment, a configuration using a wavelength conversion device as an optical waveguide device having a planar optical waveguide is particularly described. However, the application of the present invention is not limited to this. For example, a similar effect can be obtained in a modulation device having a planar optical waveguide using a 3 dB coupler, a Mach-Cheander interferometer, or the like. Also in the configuration using these, the positions of the semiconductor laser and the planar optical waveguide device on the submount are aligned with the center line of the alignment key on the semiconductor laser and the central line of the alignment key on the planar optical waveguide device. By adjusting the distances so that they coincide with each other and the distance between the opposite end faces to a desired value and mounting them, highly efficient optical coupling can be realized, and the light use efficiency can be improved. Thereby, the output of the semiconductor laser is reduced, and its practical effect is great.

In the optical waveguide device having the planar optical waveguide 3, the substrate 1 on which the planar optical waveguide 3 is formed is made of M as described in each of the above embodiments.
It is not limited to a g-doped LiNbO ₃ substrate, but may be any other suitable ferroelectric substrate used in the art. Specifically, LiTaO ₃ crystal, KTiOP
It is possible to use a substrate made of a crystal having a large nonlinear optical constant, such as an O ₄ crystal or a KNbO ₃ crystal.

In each of the above embodiments, the material of the alignment key 4 and the additional pattern 4A formed of the same material as the stripe mask for forming the planar optical waveguide 3 is a Ta film. However, the present invention is not limited to this, and may be a film of another appropriate material used in the art. Specifically, A
From the metal film such as l, Cr, or Ti / Au, particularly the metal film having a sufficiently large reflectivity to the light used for detecting the alignment key 4, the alignment key 4 and the additional pattern 4A Can be configured. Alternatively, the alignment key 4 and the additional pattern 4A may be formed by a dielectric film designed to have a large reflectance for light used for detecting the alignment key 4.

Further, in the optical waveguide device having the planar optical waveguide 3, a protective film 5 provided on the surface of the substrate 1 for protecting the alignment key 4 and adjusting the position of the planar optical waveguide 3 in the height direction. Is not limited to SiO ₂ in the above description, and may be a film of another appropriate material used in the art. For example, a film of a material such as Al ₂ O ₅ or Ta ₂ O ₅ which has a lower refractive index than the substrate and is transparent to the fundamental wave and the harmonics can be used.

In the above description, the alignment adjustment in the direction along the normal direction of the light emitting end face of the semiconductor laser and the alignment adjustment in the direction parallel to the light incident end face of the optical waveguide device are respectively described. Need not be strictly along that direction. When adjusted with a certain angle from those directions, that is, in a direction substantially along the normal direction of the light emitting end face of the semiconductor laser and in a direction substantially parallel to the light incident end face of the optical waveguide device, respectively. The present invention is applicable to the case where the alignment adjustment is performed, and the same effect can be obtained.

[0119]

As described above, according to the present invention, in an optical waveguide device having a planar optical waveguide, a small alignment key that gives only a small waveguide loss to the planar optical waveguide is formed with high positional accuracy. it can.

Further, according to the present invention, there is provided a semiconductor laser,
An optical waveguide device having a planar optical waveguide;
Since the mounting can be performed by performing the positioning adjustments a plurality of times and the positioning adjustment can be performed with high accuracy, an integrated optical module excellent in mass productivity can be provided.

Further, according to the present invention, variation in coupling efficiency between samples of the integrated optical module is reduced. It is also possible to omit the alignment adjustment for the semiconductor laser.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an optical waveguide device having a planar optical waveguide according to a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining a forming process of the optical waveguide device of FIG. 1;

FIG. 3 is a perspective view showing a configuration of a wavelength conversion device using a planar optical waveguide as a specific example of an optical waveguide device having a planar optical waveguide in the first embodiment of the present invention.

FIG. 4 is a diagram schematically illustrating an example of a second harmonic generation curve of a second harmonic generation device having an increased allowable wavelength width.

FIG. 5 is a diagram schematically showing an example of a second harmonic generation curve when an alignment key is formed in the vicinity of the planar optical waveguide in the second harmonic generation device having the characteristics of FIG. 4; is there.

FIGS. 6 (a) and (b) are a side view and a plan view showing a configuration of an integrated optical module configured according to a second embodiment of the present invention.

FIGS. 7A and 7B are a side view and a plan view showing a configuration of an integrated optical module configured according to a third embodiment of the present invention.

FIGS. 8A to 8E are diagrams illustrating steps of a method for mounting an integrated optical module according to a fourth embodiment of the present invention.

FIG. 9 is a perspective view schematically showing a configuration of an optical module according to a conventional technique.

FIG. 10 is a cross-sectional view schematically illustrating a configuration of an optical module according to another conventional technique.

FIGS. 11A and 11B are diagrams schematically showing a recognition image of an alignment key on a semiconductor laser and a wavelength conversion device obtained by a detection device with respect to an integrated optical module according to the present invention, respectively. is there.

FIG. 12 is a diagram schematically illustrating a configuration example of an integrated optical module using a planar optical waveguide device having an oblique end face to which the present invention can be applied.

[Explanation of symbols]

Reference Signs List 1 Mg-doped LiNbO ₃ substrate 2 Stripe mask 2A Opening 3 Planar type optical waveguide 4 Alignment key 4-1 Alignment key 4-2 Alignment key 4A Additional pattern 5 Protective film 7 Polarized region 11 Semiconductor laser 13 Si submount 14 Metal film 15 Solder layer 17 Alignment key 17-1 Alignment key 17-2 Alignment key 19 Laser emission unit 21 Metal film 23 Electrode 24 AlN submount 136 Detector 161 Chip hand 162 Chip hand 26 Si submount 27 Semiconductor laser 28 V groove REFERENCE SIGNS LIST 29 Optical fiber 125 Chip mounting area 126 Alignment key 127 Alignment key 30 DBR semiconductor laser 31 Active layer area 32 DBR area 33 Wavelength change using planar optical waveguide Device 34 planar optical waveguide 35 inverted regions 36 Mg-doped LiNbO ₃ substrate 37 submount 38 submount 39 wire 40 bonding wire 41 support member 50 semiconductor laser 51 planar optical waveguide device 52 planar optical waveguide 53 submount 100 planar Optical waveguide device having an optical waveguide (planar optical waveguide device) 200 Wavelength conversion device using planar optical waveguide 300 Integrated optical module 400 Integrated optical module 500 Integrated optical module A1 Center of gravity A2 Center of gravity B1 Center of gravity B2 Center of gravity M1 Center Line M2 Center line

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhisa Yamamoto 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 2H037 AA01 AA04 BA02 DA03 DA04 DA12 DA18 2H047 KA04 MA05 MA07 PA13 PA21 QA03 RA00 RA04 TA32 2K002 AA01 AA02 AB12 AB27 CA03 CA22 DA06 EA25 FA17 FA26 GA10 HA20 5F073 AA65 BA01 BA04 FA07 FA13 FA23

Claims (14)

[Claims] A ferroelectric substrate; a planar optical waveguide formed on the ferroelectric substrate; and a surface formed on the surface of the ferroelectric substrate at a predetermined distance from the planar optical waveguide. An optical waveguide device, comprising: at least an alignment key; and a protective film formed on a surface of the ferroelectric substrate so as to cover the planar optical waveguide and the alignment key. 2. The optical waveguide device according to claim 1, wherein the planar optical waveguide is a proton exchange planar optical waveguide formed by a proton exchange method. 3. The optical waveguide device according to claim 1, wherein the planar optical waveguide and the alignment key are formed using the same photomask. 4. The optical waveguide device according to claim 1, wherein said alignment key is located at a distance of at least 10 μm from said planar optical waveguide. 5. The device according to claim 1, wherein a domain-inverted region is periodically formed in said planar optical waveguide, and functions as a second harmonic generation device by quasi-phase matching.
The optical waveguide device according to any one of the above. 6. An optical waveguide device according to claim 1, further comprising: a semiconductor laser arranged so that outgoing light is optically coupled to the planar optical waveguide of the optical waveguide device. ,
An integrated optical module comprising at least: 7. A method for mounting an integrated optical module, comprising mounting at least a semiconductor laser and an optical waveguide device having a planar optical waveguide formed on a submount, wherein a light emitting end face of the semiconductor laser is provided. Detecting the edge portion of the optical waveguide device and the edge portion of the light incident end face of the optical waveguide device; and utilizing the detection results of the respective edge portions, within the surface of the submount, the semiconductor laser and the optical waveguide. Adjusting the position of the device in a direction substantially parallel to the normal direction of the light emitting end face of the semiconductor laser. 8. A semiconductor laser on which a first alignment key is formed, and a semiconductor laser on which a planar optical waveguide is formed and a second alignment key is formed.
An optical waveguide device on which an alignment key of
Detecting the first alignment key of the semiconductor laser and the second alignment key of the optical waveguide device by mounting the integrated optical module at least on a submount. In the surface of the submount, the detected first and second
Adjusting the position of the other detected alignment key in a direction substantially parallel to the light incident end face of the optical waveguide device, using any one of the alignment keys as a reference position. To implement an integrated optical module. 9. With the position of the first alignment key as a reference position, the position of the second alignment key is
The mounting method of an integrated optical module according to claim 8, wherein the alignment is adjusted in a direction substantially parallel to a light incident end face of the optical waveguide device. 10. The position of the first alignment key is adjusted in a direction substantially parallel to a light incident end face of the optical waveguide device, using the position of the second alignment key as a reference position. 9. The mounting method of the integrated optical module according to 8. 11. A first mounting step of mounting a semiconductor laser on which a first alignment key is formed on a submount, and an optical waveguide device on which a planar optical waveguide is formed and a second alignment key is formed. A second mounting step of mounting the first alignment key on the semiconductor laser and the second alignment key on the optical waveguide device. An alignment key, and using the detected position of the first alignment key as a reference position within the surface of the submount, using the detected position of the second alignment key as the light of the optical waveguide device. Adjusting the alignment in a direction substantially parallel to the incident end face; and an edge of the light emitting end face on the semiconductor laser and the light incident end of the optical waveguide device. And detecting the positions of the semiconductor laser and the optical waveguide device within the surface of the submount by using the detection results of the respective edge portions. Adjusting the alignment in a direction substantially along the normal direction of
A mounting method of an integrated optical module, comprising: 12. The integrated optical module according to claim 8, wherein the planar optical waveguide and the second alignment key are formed using the same photomask. Implementation method. 13. The mounting method for an integrated optical module according to claim 8, wherein said second alignment key is located at a position at least 10 μm away from said planar optical waveguide. 14. The mounting method for an integrated optical module according to claim 7, wherein said planar optical waveguide is a proton exchange planar optical waveguide formed by a proton exchange method.