KR100562942B1 - The Semiconductor Laser Devices Having High Degree of Polarization - Google Patents

Abstract

The present invention relates to a semiconductor laser device having a high degree of polarization required for optical communication, optical measurement, optical sensor, optical signal processing, etc., comprising: an optical waveguide formed on a substrate, a fixed semiconductor laser provided at an input end of the optical waveguide, It comprises a lattice-shaped polarizing means integrated on the optical waveguide of the output end of the semiconductor laser, the laser beam is input to the optical waveguide and guided so as to polarize in a specific direction while passing through the polarizing means.

Polarization, semiconductor laser, waveguide, polarization filter, polarizer, polarization converter, wave plate

Description

The semiconductor laser devices having high degree of polarization}

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the operation example of the filter which depends on the polarization integrated in the waveguide in order to implement the semiconductor laser device with high polarization degree which concerns on this invention.

2 is a diagram of a semiconductor laser device having a high degree of polarization configured to operate in the TE mode according to the present invention, where (a) is a plan view, (b) is a front view, and (c) is an operation diagram of the TM / TE mode. to be.

3 is a plan view of a semiconductor laser device having a high degree of polarization configured to operate in a TM mode according to the present invention.

4 is a diagram of a semiconductor laser device constructed by inserting a filter depending on polarization into an external resonator of a semiconductor laser according to the present invention, where (a) is a plan view and (b) is a front view (C) is an operation diagram of the TM / TE mode.

5 is a view showing another example of a semiconductor laser device constructed by inserting a filter depending on polarization in an external resonator of a semiconductor laser so as to operate in a TM mode according to the present invention, where (a) is a plan view and (b ) Is a front view, and (c) is an operation diagram of a TM / TE mode.

6 is a diagram showing an example of a laser device that emits various polarization modes using one filter, a splitter, and various polarization converters depending on polarization.

7 is a diagram illustrating an example of a semiconductor laser device configured on a waveguide so as to emit a plurality of different polarization modes, respectively.

8 is a plan view illustrating a lattice type polarizing filter using a mask.

9 is a diagram showing a grating formation structure using a laser interferometer.

Fig. 10 is a diagram showing a structure of forming a short period grating using a phase mask.

11 is a configuration diagram showing a semiconductor laser device according to a conventional example 1. FIG.

12 is a view showing the structure of a polarizer according to the prior art example 2, (a) and (b) are views showing the operation principle of the polarizer, and (c) is a partial front cross-sectional view of the polarizer.

Explanation of symbols on the main parts of the drawings

2: light source 4: polarization filter

5: reflector 6: optical splitter

10: polarization converter 15: substrate

20: optical waveguide 30,32: laser system

The present invention relates to a semiconductor laser device having a high degree of polarization, and more particularly, in order to obtain light having a high degree of polarization of a specific component by inserting a polarization filter in the middle in the fields of optical communication, optical measurement, optical sensor, and optical signal processing. One semiconductor laser device relates.

In general, in optical measurement systems, optical sensing systems, or optical communications, there is often a need for a laser that emits a beam of a particular polarization mode. The laser beam emitted by the semiconductor laser has its own degree of polarization. For example, in general commercially available edge-emitting semiconductor lasers, the polarization degree of the linearly polarized beam is 20 dB or less. And, in the case of surface-emitting semiconductor lasers, due to the symmetry of the structure, they emit two mutually perpendicular linear polarization modes. In this case, however, the polarization degree is very low, and there is also a problem of unstable output change characteristics between the two polarization modes due to current, lateral mode, and the like.

Therefore, in order to obtain sufficient polarization degree, it is common to use a polarizer attached to a semiconductor laser output terminal. For example, Korean Patent Publication No. 174775 (Prior Example 1) discloses an example of increasing the degree of polarization of a laser including a polarizer. This will be described below with reference to FIG. 11.

The laser light emitted from the semiconductor laser 18 passes through the collimator lens 11 and the focus lens 52 to be coupled with the incident surface of the waveguide 14 provided on the substrate 17. Then, the second harmonic light is converted into the polarization inversion region 16. At this time, in order to obtain a high conversion efficiency in the waveguide 14, it is necessary to introduce the semiconductor laser light oscillating in the TM (Transverse Magnetic) mode to the waveguide (14). For this purpose, it is necessary to match the beam shape of the semiconductor laser light with the distribution shape of the second harmonic light, which converts the semiconductor laser light emitted from the semiconductor laser 18 into a TM mode in a transverse electric (TE) mode and then guides the waveguide 14. It can be made by the method of coupling). For this purpose, in the conventional example, a polarizer such as the Brewster plate 12 is provided between the collimator lens 11 and the focus lens 52 at the output end of the semiconductor laser 18.

Another example of a polarizer using a Brewster plate is disclosed in Korean Laid-Open Patent Publication No. 1998-021941 (Prior Example 2). This relates to a polarizing device which increases the degree of polarization of a high power laser light and can remove the displacement difference on the optical path caused by the transmission of the laser light, and a representative drawing is shown in FIG. 12. As shown, the laser polarizer includes a casing 5 having a laser beam incident portion 7 on one side and a laser beam transmitting portion 8 formed on an opposite side thereof, and a predetermined interval within the casing 5. It consists of a long plate of medium 1 determined by an angle determined by Brewster's law and a predetermined equation. With this configuration, polarization degree close to 99% can be obtained and the displacement difference can be eliminated.

However, in the case of such a conventional semiconductor laser device, it is very difficult to align the Brewster plate accurately, which leads to a lot of time consumption, and there is also a problem that it is difficult to control the polarization because the angle adjustment is difficult once alignment.

In addition, conventional Brewster plates have been difficult to integrate directly into the waveguide because of their bulky size.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and provides a specific polarization filter in a laser system composed of a side emitting semiconductor laser or a semiconductor optical amplifier (hereinafter referred to as SOA). It is an object of the present invention to provide a semiconductor laser device having a high degree of polarization, which can emit light having a high degree of polarization and can also control the polarization state of a beam that emits light.

In order to achieve the above object, a semiconductor laser device having a high degree of polarization according to the present invention,

An optical waveguide formed on the substrate,

A fixed semiconductor laser installed at an input end of the optical waveguide,

A lattice type polarizing filter integrated on an optical waveguide at an output end of the semiconductor laser;

Characterized in that comprises a.

In addition, a polarization converter may be further provided at the rear output terminal of the polarization filter.

Another example of a semiconductor laser device having a high degree of polarization according to the present invention,

An optical waveguide formed on the substrate;

A semiconductor laser installed at an input end of the optical waveguide, the semiconductor laser comprising an antireflection coating and a reflection coating;

A lattice type polarizing filter integrated on an optical waveguide at an output end of the semiconductor laser;

An external resonator reflector (5) reflected through a polarization filter in a specific wavelength band;

Laser system 32 configured to include is characterized in that installed on the input end of the optical waveguide (20).

In addition, a polarization converter may be further provided on the optical waveguide at the output end of the laser system.

Another example of a semiconductor laser device having a high degree of polarization according to the present invention,

An optical waveguide formed on the substrate;

A semiconductor laser installed at an input end of the optical waveguide and comprising an anti-reflective coating portion and a reflective coating portion, a lattice type polarizing filter integrated on the optical waveguide at the output end of the semiconductor laser, and a reflection in a specific wavelength band passing through the polarizing filter A laser system comprising a reflector for an external resonator and installed at an input end of an optical waveguide;

An optical splitter installed on the optical waveguide at the output end of the laser system;

A polarization converter installed on a plurality of optical waveguides branched from the optical splitter;

Characterized in that comprises a.

Another example of a semiconductor laser device having a high degree of polarization according to the present invention,

M optical waveguides formed on the substrate;

A semiconductor laser installed at an input end of the optical waveguide and comprising an anti-reflective coating portion and a reflective coating portion, a lattice type polarizing filter integrated on the optical waveguide at the output end of the semiconductor laser, and a reflection in a specific wavelength band passing through the polarizing filter M laser systems comprising a reflector for an external resonator and installed at an input end of the optical waveguide;

A polarization converter installed in m-1 optical waveguides among the m optical waveguides;

Characterized in that comprises a.

The grating plane of the polarizing filter is preferably a grating inclined at Brewster's angle θ _B.

In addition, the lattice plane of the polarizing filter is preferably composed of two or more.

The grating can be integrated by irradiating an ultraviolet (UV) laser beam through a phase mask or amplitude mask and then irradiating it on an optical waveguide with light sensitivity.

Instead, the grating can be integrated by passing an ultraviolet laser beam through an ultraviolet laser interferometer and then irradiating it on an optical waveguide with light sensitivity.

In addition, the axis of the mask may be inclined by a predetermined angle with respect to the optical waveguide.

In addition, the polarizer is preferably a wave plate. In this case, the wave plate may be formed by irradiating a UV wave to the optical waveguide to cause birefringence in the optical waveguide.

In addition, the polarizer may be tuned by heat or electric field.

In addition, the reflector for the external resonator may be made of a grating. At this time, the grating is preferably integrated by passing an ultraviolet laser beam through a phase mask and then irradiating it on an optical waveguide with light sensitivity.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the accompanying drawings, Figure 1 is a view illustrating an operation example of a filter depending on the polarization integrated in the waveguide to implement a semiconductor laser device having a high degree of polarization according to the present invention, Figure 2 is a configuration configured to operate in TE mode 3 is a diagram of a semiconductor laser device having a high degree of polarization of the invention, FIG. 3 is a diagram of a semiconductor laser device having a high degree of polarization of the present invention configured to operate in a TM mode, and FIG. 4 is an internal resonator of a semiconductor laser to operate in a TE mode. FIG. 5 is a view illustrating a semiconductor laser device having a high degree of polarization according to the present invention configured by inserting a filter depending on polarization. FIG. 5 is a view illustrating a semiconductor laser device having a polarization dependent filter inserted into an external resonator of a semiconductor laser to operate in a TM mode. A diagram of a semiconductor laser device having a high degree of polarization, FIG. 6 shows one filter and a minute depending on polarization. Showing an example of a laser device that emits various polarization modes using a polarizer and various polarization converters. FIG. 7 is a view showing an example of a semiconductor laser device configured on a waveguide so as to emit a plurality of different polarization modes. 8 is a diagram showing a lattice type polarization filter using a mask, FIG. 9 is a diagram showing a lattice forming structure using a laser interferometer, and FIG. 10 is a diagram showing a forming structure of a short period grating using a phase mask.

The basic configuration of the present invention is to provide polarization means that can selectively transmit, scatter or reflect depending on the polarization state of the input beam in order to select the polarization state of the output light and to increase the degree of polarization.

The polarizing means may be a polarizing filter or a polarizing converter. The polarization filter uses a grating inclined at a Brewster angle. In addition, a wave plate may be cited as an example of the polarization converter. Based on this, an embodiment of the present invention will be described.

1 illustrates a polarization filter or a grating integrated on a flat waveguide in order to implement a semiconductor laser device having a high degree of polarization, the grating plane of which is inclined at the Brewster angle, and the grating has several periodic layers having refractive indexes of n1 and n2 values. Consists of The lattice plane need not necessarily coincide with the Brewster's angle, but is sufficient to be in the vicinity thereof.

In this case, the refractive index n1 is the refractive index of the flat waveguide 20 of the portion not exposed to the laser beam, and n2 represents the refractive index of the changed flat waveguide 20 of the portion exposed to the light.

In the lattice, a layer having a refractive index of n 2 is repeated for each periodic lambda (Λ), which is called a grating plate. In addition, when the inclined angle of the grating plane corresponds to the Brewster angle, these gratings behave like polarizers using multiple Brewster glass layers to make light polarized in one direction. Accordingly, only the TE polarization component may be output through the grating for the unpolarized incident beam having both the TE polarization component and the TM polarization component. Also, the Brewster angle θ _B is determined according to the refractive indices n1 and n2 as follows.

θ _B = tan ^-1 (n2 / n1) ... (1)

Or θ _B = tan ^-1 (n1 / n2)

Therefore, when n1 and n2 are similar, the angle is 45 °, and when the n2 value is adjusted, the Brewster angle is changed. Alternatively, when the angle of inclination is already fixed, when the value of n 2 is adjusted, the degree of polarization of the polarized light passing through the inclined grating (consumption ratio: TE polarization component size versus TM polarization component size) is changed. Alternatively, when n1 and n2 are fixed, the degree of polarization varies when the inclination angle is changed from the θ _B value.

In the flat waveguide type laser device according to the present embodiment, the substrate 15 is made of silica, and the waveguide 20 corresponding to the core is made of silica doped with impurities such as germanium (Ge). . In addition, the flat waveguide polarizing filter is a device that filters only polarized components polarized in a specific direction among light waves passing through the optical waveguide, and is a basic device useful for various integrated optical optics.

Specifically, as shown in FIG. 1, when the TE (Transverse Electric mode) and the TM (Transverse Magnetic mode) polarization modes enter the grating together, all of the TE mode components are transmitted and some or all of the TM mode components are transmitted. Because it is scattered in the vertical direction, some or no light comes out of the output beam. Accordingly, the grating as shown in FIG. 1 has a function of a polarizing filter or a polarizer. That is, a planar waveguide polarizer or a polarizing filter that acts as if it is a Brewster glass layer is provided.

Here, the TE wave (Transverse Electric wave) refers to a wave in which the electric field is perpendicular to the axial direction of the waveguide among the optical waves in the waveguide but the axial component is not perpendicular to the magnetic field. The TM wave (Transverse Magnetic wave) means a mode in which the magnetic field is perpendicular to the axial direction of the waveguide among the optical waves in the waveguide, but the axial component is not perpendicular to the electric field.

In addition, a method of manufacturing a lattice, which is a flat waveguide polarizer in the present invention, will be described in more detail. As shown in FIG. 8, a flat waveguide (Ge-doped silica) having a light sensitivity of a mask (phase mask or amplitude mask) is shown. After aligning at a specific angle on the upper side), irradiating ultraviolet (UV) light from above may tilt the Brewster angle in the waveguide to generate a grating.

Alternatively, the lattice may be formed by passing a UV laser beam through a laser interferometer and then irradiating a flat waveguide (Ge doped silica) with light sensitivity.

When the grating is constituted in this manner, the grating can be formed in the waveguide, so that the overall structure can be miniaturized.

In this case, it is possible to obtain high efficiency by increasing the total length of the polarizer without accurately adjusting the Brewster angle. The gratings are generated periodically and serve as one Brewster plate per grating. Therefore, hundreds to thousands or more of gratings can be manufactured at a small size, so that a high efficiency polarizer can be easily obtained, and high efficiency can be maintained by using a large number of gratings without maintaining an accurate Brewster angle.

9 (a) and 9 (b) show a grating formation method using an ultraviolet laser interferometer, and FIG. 10 shows a grating formation method using a phase mask.

2 illustrates an embodiment of the present invention, in which a semiconductor laser 2 is formed at an input end of an optical waveguide 20 formed on a substrate, and an optical waveguide 20 at an output end of the semiconductor laser 2 is formed. The laser system 30 is provided with a polarizer 4 on the top, and the polarization degree is increased by transmitting the laser beam emitted from the semiconductor laser LD 2 through the polarizer 4 integrated on the waveguide 20. Given.

A detailed configuration method is as follows.

First, a cladding portion for forming a waveguide on a silica substrate, Ge, and the like are doped to fabricate a core portion having a high refractive index, and a semiconductor laser is attached to the core portion of the manufactured waveguide so that the light output from the laser is the core. Align to be guided into parts. Next, the core part made on the PLC is irradiated with a UV laser beam using a mask (see FIG. 8) or a lattice type polarizing filter or polarizer is formed using a laser interferometer.

Accordingly, looking at the overall transmission path of the light, first, the beam output from the semiconductor laser is condensed into the core portion on the PLC, in which the beam is mixed with TE / TM, and the polarizer 4 operating as described above. While passing through, all or part of the TM mode beam is reflected or scattered out of the core to obtain a TE mode beam having a different degree of polarization at the final output stage. In this case, the degree of polarization is enabled by changing the inclination angle of the grating or adjusting the length of the grating. As a result, all TM mode beams may be removed through the polarization filter, and some may be transmitted through the polarization filter.

3 shows another embodiment of the present invention, in which the polarization converter 10 is further configured on the optical waveguide 20 at the output end of the polarizer 4 in the semiconductor polarizer disclosed in FIG. 2. .

The polarization converter 10 is a wave plate integrated in a waveguide shape of a special structure or inserted in the middle of the waveguide in a crystalline form.

In particular, FIG. 3 illustrates a case where the polarization converter 10 is a λ / 2 wave plate. If the TE polarized light passes through the polarizer 10, it will be output as TM polarized light as shown in FIG.

In addition, it can be seen that if the wave plate is composed of a λ / 4 wave plate, it is output as circularly polarized light. When the phase delay value between the TE and TM modes in the wave plate becomes a value other than an integral multiple of 180 ° (λ / 2 wave plate) or 90 ° (λ / 4 wave plate), the polarization converter 10 The output beam will be an elliptical polarized beam. Therefore, by adjusting the polarization converter 10, it is possible to output a beam of any polarization state.

FIG. 4 shows another embodiment of the present invention. An external cavity laser (ECL) capable of adjusting the degree of polarization by inserting a polarization filter 40 between the semiconductor laser 2 and the reflector 5 for an external resonator is illustrated. It is made up.

In this embodiment, one side of the semiconductor laser 2 is composed of the reflective coating part HR, but the other side is composed of the antireflective coating part AR, and reflectance is applied to the outside of the semiconductor laser 2 in order to cause resonance. Consists of adjustable reflector 5 for the external resonator. The reflector 5 for configuring the external resonator may be implemented by a grating. At this time, the grating is preferably produced in a short period by exposing the pattern of the UV laser beam from the phase mask to a flat waveguide with light sensitivity for a predetermined time.

In addition, as shown in FIG. 4 (c), because of the characteristics of the ECL, the laser beam is output as a resonance phenomenon in which the traveling path of the light is reciprocated numerous times between the semiconductor laser 2 and the external reflector / lattice 5. Since each pass of the polarization filter / polarizer 40 is caused once the resonance has the advantage that can increase the efficiency even without maintaining the correct Brewster angle. In addition, the input laser beam oscillates and emits in a specific polarization mode while reciprocating between the laser 2 and the reflector 5. In the case of FIG. 4, the emitted beam becomes a TE polarization mode having a high erase ratio.

FIG. 5 shows another embodiment of the present invention, in which the polarizer 10 is further configured on the optical waveguide 20 at the output end of the laser system 32 in FIG.

The polarization converter 10 may be implemented by integrating a wave plate in a waveguide, or may be manufactured by inserting a crystalline wave plate in the middle of the waveguide. In addition, as described with reference to FIG. 3, an arbitrary polarization beam may also be output by selecting or tuning a specific polarization converter 10. Here, tuning the wave plate means tuning the phase delay difference between the two modes in the wave plate. Tuning methods include applying an electric field or applying heat. As a method of implementing a polarization converter by integrating a wave plate in a waveguide, it is preferable to form a birefringence by irradiating a predetermined portion of the waveguide for a predetermined time. This method is described in T. Erdogan and V. Mizrahi, "Characterization of UV-induced birefringence in photosensitive Ge-doped silica optical fibers," J. Opt. Soc. Am. B, Vol. As disclosed in 11, pp21002105, 1994, the size of the photoinduced birefringence can be maximized by irradiating a polarized laser beam (often an excimer laser beam) in a direction perpendicular to the waveguide direction. Since the magnitude of the birefringence and the phase delay due to the birefringence vary depending on the irradiation time of the laser beam, an appropriate wavelength plate can be formed by adjusting the irradiation amount. In addition, since the birefringence value varies with temperature, the temperature delay can be tuned by adjusting the temperature.

FIG. 6 shows an embodiment of the invention with a semiconductor laser system that emits a plurality of different polarized beams, wherein an optical splitter 6 is provided at the output of the same laser system 30, 32 as in FIG. 2 or 4. ), And configure the polarization transducers 10, 10-1, 10-2, ..., 10-m as shown in the figure to horizontally polarized beam, vertically polarized beam, and linearly polarized in any direction. Laser systems that emit both polarized beams, left-circularly polarized light and right-circularly polarized light, and elliptically polarized beams are integrated on one substrate.

It is preferable that the polarization filter 4 is a grating inclined at a Brewster angle, and the reflector 5 is preferably a Bragg grating.

FIG. 7 shows an embodiment of the invention with a semiconductor laser system that emits a plurality of different polarized beams, in order to emit m different polarized beams, first of all horizontally polarized beams (TE mode) can be made through the laser system, and each of the polarizers can be configured to emit various polarized beams. As shown in the drawing, a laser system that emits not only linear polarization and circular polarization but also other kinds of polarization modes may include a laser system including a plurality of light sources 2-1, 2-2, ..., 2-m, and a polarization filter. (30,30-1, 30,32-2…, 30,32-m) and polarization converters 10-1, 10-2,…, 10- (m-1) can be implemented on a substrate. have.

As such, although a laser system emitting multiple polarization modes may be simultaneously configured on a substrate, only one or two laser systems emitting only one or two specific polarization modes may be configured.

Meanwhile, a silica substrate having excellent optical and thermal characteristics and easy commercialization is used as the substrate 15, and the light source 2 or SOA should be fixed on the silica substrate and aligned so that the laser beam can be coupled to the waveguide. . As the waveguide, germanium (Ge) is doped with silica (SiO ₂ ) so that the reflector, the polarizing filter, and the wave plate can be directly integrated into the UV beam.

As a method of integrating the wave plate, there is a method of causing birefringence by irradiating a UV beam.

The semiconductor laser device according to the present invention has a function of tuning the polarization state of the output laser beam as well as the semiconductor laser in which the polarization component is fixed and emitted. At this time, the method of controlling the polarization is possible by changing the phase of the wave plate by applying electricity or heat to the wave plate.

In addition, a semiconductor amplifier may be used as a power source instead of the semiconductor laser.

According to the present invention having the above-described configuration, by additionally equipped with a small polarization filter or a polarization converter can be used in place of the conventional light source in a system that requires a polarizing beam, it is possible to obtain a high degree of polarization and low cost There is this.

In addition, even if each grating plane does not exactly coincide with the Brewster angle, there is an advantage in that a high degree of polarization can be effectively obtained by adjusting the overall length of the polarizer.

In addition, the use of a polarization converter has the advantage that it can output a laser beam of various polarization state even with a single semiconductor laser.

Claims (16)

delete delete An optical waveguide formed on the substrate; A semiconductor laser installed at an input end of the optical waveguide, the semiconductor laser comprising an antireflection coating and a reflection coating; A lattice type polarizing filter integrated on an optical waveguide at an output end of the semiconductor laser; A reflector for an external resonator reflected through a polarization filter in a specific wavelength band; The semiconductor laser device having a high degree of polarization, characterized in that the laser system configured to be installed at the input end of the optical waveguide. The method of claim 3, And a polarization converter on the optical waveguide at the output end of the laser system. An optical waveguide formed on the substrate; A semiconductor laser installed at an input end of the optical waveguide and comprising an anti-reflective coating portion and a reflective coating portion, a lattice type polarizing filter integrated on the optical waveguide at the output end of the semiconductor laser, and a reflection in a specific wavelength band passing through the polarizing filter A laser system comprising a reflector for an external resonator and installed at an input end of an optical waveguide; An optical splitter installed on the optical waveguide at the output end of the laser system; A polarization converter installed on a plurality of optical waveguides branched from the optical splitter; The semiconductor laser device having a high degree of polarization, characterized in that it comprises a plurality of laser beams of the polarization state is emitted simultaneously. M optical waveguides formed on the substrate; A semiconductor laser installed at an input end of the optical waveguide and comprising an anti-reflective coating portion and a reflective coating portion, a lattice type polarizing filter integrated on the optical waveguide at the output end of the semiconductor laser, and a reflection in a specific wavelength band passing through the polarizing filter M laser systems comprising a reflector for an external resonator and installed at an input end of the optical waveguide; A polarization converter installed in m-1 optical waveguides among the m optical waveguides; A semiconductor laser device having a high degree of polarization, comprising a. The method according to any one of claims 3 to 6, The lattice plane of the polarization filter is a semiconductor laser device having a high degree of polarization, characterized in that the lattice inclined at the Brewster angle (θ _B ). The method according to any one of claims 3 to 6, The lattice plane of the polarization filter is a semiconductor laser device having a high degree of polarization, characterized in that composed of two or more. The method according to any one of claims 3 to 6, And the grating is integrated by irradiating an ultraviolet (UV) laser beam through a phase mask or an amplitude mask and then irradiating it on an optical waveguide with a light sensitivity. The method according to any one of claims 3 to 6, And the grating is integrated by irradiating an ultraviolet laser beam through an ultraviolet laser interferometer and irradiating it on an optical waveguide with a light sensitivity. The method of claim 9, And the axis of the mask is inclined with respect to the optical waveguide by a predetermined angle. The method according to any one of claims 4 to 6, The polarizing device is a semiconductor laser device having a high degree of polarization, characterized in that the wave plate. The method of claim 12, The wavelength plate is formed by irradiating a UV wave to an optical waveguide to cause birefringence in the optical waveguide. The method of claim 12, The polarizer has a high degree of polarization semiconductor laser device, characterized in that the tuning by heat or electric field. The method according to any one of claims 3 to 6, The reflector (5) for the external resonator is a semiconductor laser device having a high degree of polarization, characterized in that the grating. The method of claim 15, The grating is integrated by irradiating an ultraviolet laser beam through a phase mask and then irradiating onto an optical waveguide with a light sensitivity.

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