JPH0730207A - Semiconductor laser array module and method for assemblying the same - Google Patents

Abstract

PURPOSE:To stabilize the light emission frequency of a downsized light source by using a polarizer, which permits two orthogonally intersecting polarized beams to be transmitted by a polarizing prism and permits the incident plane of semiconductor laser array beams to the bonded plane is orthogonal to the plane including the semiconductor laser array. CONSTITUTION:As a polarizer 9 on the incident side of an optical isolator 4, a polarizing prism formed by joining two prisms is used and the polarizer 9 allows two orthogonally intersecting polarized beams to pass. Therefore, the optical isolator 4 which allows no internal reflection is provided. Since the polarizer 9 permits the incident plane of beams to the laminating plane to orthogonally intersect with the plane which includes a semiconductor laser array 1, the size of the polarizer 9 is reduced and the optical isolator 4 is downsized. Therefore, the frequency of light emitted by the semiconductor laser is stabilized and the downsized semiconductor laser array module is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source for optical communication, and more particularly to a transmission light source used for optical frequency division multiplexing (optical FDM) communication.

[0002]

2. Description of the Related Art Research on an optical FDM communication system is being advanced as a future large capacity optical communication system. The transmitter in the above optical FDM communication system requires a plurality of light sources having different wavelengths (optical frequencies) for each channel. As the above light source, a semiconductor laser array that integrates semiconductor lasers is built in, and a lens system that accurately couples the emitted light to the optical fiber array that is the transmission line, and the optical frequency of the light source that suppresses the return light to the semiconductor laser A semiconductor laser array module having an optical isolator that stabilizes is required to be compact, to stabilize the optical frequency of the light source, and to improve an assembly method for accurately matching the relative positions of the semiconductor laser array and the optical fiber array. Has been.

As a conventional semiconductor laser array module of this type, for example, the Institute of Electronics, Information and Communication Engineers OCS89-6.
There is one shown in 7. FIG. 9 is an overall configuration diagram based on the semiconductor laser array module shown in the above document. In FIG. 9, 1 is a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, 2 is an optical fiber array in which optical fibers corresponding to the above semiconductor lasers are arranged in a line, and 3 is each channel from the semiconductor laser array 1. A collimator lens 4 for converting emitted light into parallel light, an optical isolator 4 for transmitting only light in one direction from the semiconductor laser array 1 to the optical fiber array 2 and suppressing return light, and a reference numeral 5 for emitting light from the optical isolator 4. A condenser lens coupled to each channel of the optical fiber array 2, 6 is a thermistor for temperature detection of the semiconductor laser array 1, 7 is a chip carrier provided with the semiconductor laser array 1 and the thermistor 6, and 8 is a semiconductor laser array. 1 is a power supply line that supplies a current.

In the conventional semiconductor laser array module shown in FIG. 9, the light emitted from the semiconductor laser array 1 is converted into parallel light by a collimator lens 3, and is passed through an optical isolator 4 to a optical fiber array 2 by a condenser lens 5. Combined and output. Further, the temperature of the semiconductor laser array 1 is controlled so that the temperature detected by the thermistor 6 becomes constant, and the wavelength of the semiconductor laser array 1 is stabilized even if the ambient temperature changes.

Next, FIG. 10 is a sectional view illustrating the configuration of the conventional optical isolator of FIG. 10A is a sectional view parallel to the optical axis of the optical isolator, and FIG. 10B is a sectional view perpendicular to the optical axis of the optical isolator (B- of FIG. 10A).
It is a B sectional view). In the figure, 9 is a polarizer for converting incident light into linearly polarized light, 10 is a Faraday rotator for rotating the incident polarized light by 45 degrees, 11 is an analyzer, 12 is a magnet for magnetizing the Faraday rotator 10, and 13 is the above-mentioned. This is a holder that holds the polarizer 9, the analyzer 11, and the magnet 12.

The conventional optical isolator 4 used in the semiconductor laser array module includes a polarizer 9 and an analyzer 11.
As the above, a polarization beam splitter (PBS) that reflects an unnecessary polarization component by a dielectric multilayer film, or one that utilizes absorption of specific polarization by a fine metal fiber is used. However, in the case of a type that reflects unnecessary polarization components, such as PBS, the reflected light may scatter on the inner surface of the holder,
Further, the type utilizing absorption by the fine metal fibers is scattered by the fine metal fibers and becomes a return light to the semiconductor laser, and as a result, the oscillation light frequency of the semiconductor laser becomes unstable. The reflected return light from the optical component can be prevented by tilting the optical component with respect to the incident light, but it is not effective for the above scattering. In addition,
The scattered light from the analyzer 11 of the optical isolator is transmitted through the Faraday rotator 10 and the polarized light is rotated by 45 degrees again. Therefore, this polarized light is shielded because it coincides with the light-shielding polarization direction of the polarizer 9, and is not coupled to the semiconductor laser. Therefore, the scattering from the analyzer 11 does not affect the semiconductor laser.

As a method of preventing the return light due to the scattering from the polarizer 9 as described above, it is considered that the polarizer 9 is a polarizing prism in which two prisms are bonded to each other, and two orthogonal polarizations are transmitted. There is a Rochon prism as a polarization prism of this type. FIG. 11 is a perspective view illustrating the configuration of a polarizer of the conventional optical isolator of FIG. In the figure, 14 is a Rochon prism, 15 is a bonding surface of two prisms of the Rochon prism 14,
Reference numeral 16 is an emission beam of the semiconductor laser array, 17 is an incident surface of the emission beam 16 of the semiconductor laser array incident on the surface 15, 18 is a surface including the semiconductor laser array 1, 19 is an incident light beam to the Rochon prism, and 20 is P-polarized outgoing light rays, 21 is S-polarized outgoing light rays, 22 is an arrow indicating the polarization direction of P-polarized light, and 23 is an arrow indicating the polarization direction of S-polarized light. Of the rays emitted from the Rochon prism, polarized light parallel to the incident surface 17 is emitted parallel to the incident ray 19 (emitted ray 20 of P polarized light), while polarized light perpendicular to the incident surface 17 is at an angle with respect to the incident ray 19. Are emitted (S-polarized outgoing light beam 21). Therefore, in the Rochon prism, the incident light beam is P
It is desirable to use it so that it becomes polarized light. Since the polarization direction of the outgoing beam 16 of the semiconductor laser array 1 is parallel to the surface 18 including the semiconductor laser array 1, when the Rochon prism 14 is used as an optical isolator,
As shown in FIG. 11, a bonding surface 1 of two prisms
The tilt direction of 5 is in the array direction. Therefore, the entire shape of the outgoing beam 16 of the semiconductor laser array 1 incident on the Rochon prism 14 is large in the laser array direction, and in the Rochon prism, the inclination direction of the bonding surface 15 of the two prisms is in this array direction. (Face 15
Since the incident surface 17 on is parallel to the surface 18, there is a problem that the polarizer becomes large in the optical axis direction and the optical isolator becomes large.

In this type of polarizing prism, the angle of the two prisms to be bonded together is the output light beam 2 of P polarization.
It is determined by the separation angle of the outgoing light beam 21 of 0 and S polarization, and when the necessary separation angle is determined, it cannot be changed. Further, when the Rochon prism is used as a polarizer of the optical isolator, the reflected return light enters the polarizer as S-polarized light and is emitted at an angle within the plane of the incident surface 17. Therefore, in the case of a semiconductor array module,
It may be incident on another semiconductor laser.

Next, FIG. 12 is a diagram for explaining the magnet of the conventional optical isolator of FIG. In the case of the semiconductor laser array module, the overall shape of the beam 16 of the semiconductor laser array 1 incident on the optical isolator 4 becomes large in the array direction, and the inner diameter of the magnet becomes large to match the effective diameter of the optical isolator. In the case of a hollow cylindrical magnet, the diameter of the hollow portion is determined by this enlarged beam shape.
On the other hand, if the inner diameter of the magnet is increased to obtain the required magnetic field strength, the outer diameter is further increased, and thus the optical isolator becomes large.

As an example, a trial calculation value of the size of a magnet required when an emission beam from a single semiconductor laser is φ1 mm and an effective diameter of 1 mm × 4 mm is secured by four elements is shown. FIG. 12A is a sectional view perpendicular to the optical axis of the optical isolator. FIG. 12B shows the direction of the optical axis (Z
It is a figure (calculation value) which shows the magnetic field strength of a (direction). In the figure, 10, 12, and 13 are the same as those in FIG.
Reference numeral 6 denotes an outgoing beam from the semiconductor laser. 12
The calculation condition of (b) is to use a magnet material having a residual magnetic flux density of 10 k (Gauss), and the magnet has an outer diameter of 6.5 mm, an inner diameter of 4 mm, and a length in the optical axis direction of 6 mm. From the center of the magnet to the optical axis (Z direction)
A magnetic field strength of 1500 (Oe) or more is obtained within a range of ± 1 mm.

Next, FIG. 13 is an external view illustrating the structure of the main part of the semiconductor laser array shown in FIG. 9. As a semiconductor laser array for optical FDM communication, for example, the 1991 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers C-126. As shown in.
In the figure, 24 a and 24 b are electrodes of the semiconductor laser array 1. As shown in this figure, the semiconductor laser array 1 for optical FDM communication has a plurality of electrodes in a single semiconductor laser in order to widen the wavelength variable width. Therefore, a large number of power supply lines 8 are required and they are densely packed near the semiconductor laser array 1, so that the thermistor 6 cannot be mounted in the immediate vicinity of the semiconductor laser array 1. Therefore, the thermistor 6
The temperature detected by does not accurately reflect the temperature of the semiconductor laser array 1, and the temperature control of the semiconductor laser array 1 becomes incomplete. Since the oscillation light frequency of the semiconductor laser changes depending on the temperature, incomplete temperature control makes the oscillation light frequency of the semiconductor laser unstable.

Next, as a conventional method for adjusting the position of an optical fiber array when assembling a semiconductor laser array module, there is, for example, one disclosed in Japanese Patent Laid-Open No. 4-284408. As a conventional position adjusting method, in the case of a module using a single semiconductor laser, the position of the optical fiber in the direction of the optical axis is fixed, and coupling is made in two axes perpendicular to the optical axis, so that the coupled light output increases. There is a method of moving to and searching for and determining the optimum bonding position. In the case of a semiconductor laser array module, there are a plurality of image forming points of each semiconductor laser, and these image forming points are generally neither evenly spaced nor collinear due to distortion of the optical system. For this reason, the position of the optical fiber array is adjusted by searching for the optimum coupling position where the combined light output of the image forming points of the respective semiconductor lasers and the respective optical fibers of the corresponding optical fiber array are uniform and maximized as a whole. However, it is necessary to assemble the semiconductor laser array module. In the above document, the optical fiber array is moved in the array vertical direction and the array direction of the semiconductor laser array, and the light receiving power of each of the optical fibers on both sides of the optical fiber array and the light receiving power of the remaining optical fibers of the optical fiber array are collected. It measures the electric power and adjusts the relative position of the optical fiber array so that the optical output of each optical fiber is uniform and maximizes as a whole. It is necessary to move the optical fiber array several times in the direction to find the optimum coupling position.

[0013]

Since the conventional semiconductor laser array module is constructed as described above, and the conventional method for assembling the semiconductor laser array module is as described above, There were the following issues.

In the conventional optical isolator of the semiconductor laser array module, the PBS which reflects the unnecessary polarization component by the dielectric multilayer film and the one which has the polarizer utilizing the absorption of the specific polarization by the fine metal fiber are reflected light. Is scattered on the inner surface of the holder or is scattered by fine metal fibers and is coupled to the semiconductor laser as return light. As a result, there is a problem that the oscillation light frequency of the semiconductor laser becomes unstable. Therefore, there is a problem that a polarizing prism in which two prisms are bonded to each other and which transmits two polarized lights becomes large in the optical axis direction, and the optical isolator and therefore the semiconductor laser array module become large.

Further, since the magnet of the optical isolator of the conventional semiconductor laser array module has a larger beam shape of the semiconductor laser array in the array direction than that of a single semiconductor laser, the effective diameter of the optical isolator depends on the incident beam shape. If the inner diameter of the hollow cylindrical magnet of the optical isolator is increased so as to match the above, the outer diameter of the magnet must also be increased, which causes a problem that the semiconductor laser array module becomes large.

Further, in the semiconductor laser array chip carrier used in the conventional semiconductor laser array module, many power supply lines are concentrated in the semiconductor laser array in the vicinity of the semiconductor laser array, and the temperature detector is mounted in the vicinity of the semiconductor laser array. However, there is a problem that temperature detection for temperature control of the semiconductor laser array cannot be accurately performed unless it can be mounted in the vicinity.

A conventional method for adjusting the position of an optical fiber array, which is a method for assembling a semiconductor laser array module, comprises:
Move the optical fiber array in the vertical and array directions of the semiconductor laser array so that the optical output of the optical fibers at both ends of the optical fiber array is uniform and the optical output of the remaining optical fibers of the optical fiber array is maximized. When adjusting the relative position of the optical fiber array, there is a problem that it is necessary to move the optical fiber array several times in the array vertical direction and the array direction to match the optimum coupling position.

The present invention has been made in order to solve the above-mentioned problems, and the optical isolator incorporated therein is miniaturized, and the return light to the semiconductor laser array is suppressed, so that the optical frequency of the light source is stabilized. It is an object of the present invention to obtain a semiconductor laser array module that is made into a semiconductor.

Another object of the present invention is to obtain a miniaturized semiconductor laser array module by reducing the effective sectional area perpendicular to the optical axis of the magnet of the built-in optical isolator.

It is another object of the present invention to obtain a semiconductor laser array module in which the accuracy of temperature detection of the semiconductor laser array is improved and the optical frequency of the light source is stabilized against changes in ambient temperature.

It is another object of the present invention to provide a method for assembling a semiconductor laser array module, which can easily perform relative position adjustment for optically optimally coupling the semiconductor laser array and the optical fiber array in a short time.

[0022]

In order to achieve the above object, the invention of claim 1 provides a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a row, and an optical fiber corresponding to each of the semiconductor lasers. An optical fiber array arranged in a row, a lens system for optically coupling, and a semiconductor laser array module having an optical isolator for suppressing return light to the semiconductor laser, in the incident side of the optical isolator The polarizer is a polarizing prism in which two prisms are bonded together, and transmits two polarized lights that are orthogonal to each other, and the incident surface of the incident beam on the bonding surface is orthogonal to the surface including the semiconductor laser array. It is what

According to a second aspect of the present invention, a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line and an optical fiber array in which optical fibers corresponding to each of the semiconductor lasers are arranged in a line are optically provided. In a semiconductor laser array module having a lens system for coupling to the semiconductor laser and an optical isolator for suppressing the return light to the semiconductor laser, the magnet shape of the optical isolator is adjusted to the shape of the beam emitted from the semiconductor laser array. Thus, the size of the cross section perpendicular to the optical axis in the array vertical direction is made smaller than the size in the array direction.

Further, the invention of claim 3 includes a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, and an optical fiber array in which optical fibers optically coupled to the respective semiconductor lasers are arranged in a line. In a semiconductor laser array module having, a power supply line to the semiconductor laser array is arranged on the left and right of the semiconductor laser array, and a temperature detector is provided in the vicinity of the rear surface of the semiconductor laser array and on the rear emission beam of the semiconductor laser array. It is arranged diagonally.

Further, the invention of claim 4 has a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, and an optical fiber array in which optical fibers optically coupled to each of the semiconductor lasers are arranged in a line. In the method of assembling the semiconductor laser array module, the relative position of the optical fiber array is adjusted in the following steps. (1) First, the optical fiber array is moved in the optical axis direction, and the optical fiber array is arranged at a position where the combined light output to the optical fiber array has a maximum value or a predetermined value. The fiber array is swept in the array vertical direction of the semiconductor laser array, the combined light output to the plurality of optical fibers of the optical fiber array is measured at a plurality of points, and the distribution of the combined light output of each of the optical fibers is estimated. The optimum coupling position of each optical fiber is obtained from the distribution, the distance between the optimum coupling positions of the optical fiber array at both ends of the optical fiber array or closest to the both ends, and the distance between the corresponding optical fibers The angle formed by the array surface of the laser array and the array surface of the optical fiber array is calculated, and the angle formed by the two surfaces is set to zero. Perform angle adjustment of (3) Next, the optical fiber array is swept to the array vertically above the semiconductor laser array, to measure the combined light output to a plurality of optical fibers of the optical fiber array at a plurality of points,
Estimate the distribution of the combined optical output of each optical fiber, find the optimum coupling position of each optical fiber from the distribution, and give a predetermined weight to the optimum coupling position of each optical fiber to obtain the optimum coupling of each optical fiber. The center of gravity of the position is calculated, and the position of the center of gravity is adjusted in the array vertical direction of the optical fiber array. (4) Then, the optical fiber array is swept in the array direction of the semiconductor laser array to By measuring the combined light output to a plurality of optical fibers at a plurality of points, the distribution of the combined light output of each of the optical fibers is estimated, the optimum coupling position of each optical fiber is obtained from the distribution, and each of the above optical fibers is Predetermined weighting is applied to each optimum coupling position to obtain the barycentric position of the optimum coupling position of each optical fiber, and the position of the optical fiber array in the array direction is adjusted to the barycentric position. Do.

[0026]

According to the invention of claim 1, which is configured as described above, as a polarizer on the incident side of the optical isolator, it is a polarizing prism in which two prisms are bonded together, and two orthogonal polarized lights are transmitted, and By using a polarizer in which the incident surface of the semiconductor laser array beam on the bonding surface is orthogonal to the surface including the semiconductor laser array, internal reflection of the optical isolator can be eliminated and the optical isolator can be miniaturized.

According to the second aspect of the invention, the shape of the magnet of the optical isolator is matched with the shape of the beam emitted from the semiconductor laser array, and the size of the cross section perpendicular to the optical axis direction in the array vertical direction is smaller than the size in the array direction. By making it smaller, the effective diameter in the array vertical direction of the cross section perpendicular to the optical axis direction of the magnet can be made the same as the effective diameter in the case of a single semiconductor laser. It is possible to suppress an increase in size.

According to the third aspect of the present invention, the feeder lines of the semiconductor laser array are arranged on the left and right sides of the semiconductor laser array, and the temperature detector is arranged on the rear surface of the semiconductor laser array. The temperature can be detected more accurately, and the influence of the reflected return light from the temperature detector can be eliminated by arranging the temperature detector obliquely with respect to the rear emission beam of the semiconductor laser array. .

Further, in the step of adjusting the positions of the optical fiber array of the present invention in the two axial directions perpendicular to the optical axis direction of the optical fiber array, the optical fiber array is swept in the respective axial directions to obtain a plurality of optical fibers. The coupled light output to the optical fiber is measured at several points, and the distribution of the coupled light output of each of the optical fibers is obtained by the Gaussian beam theory to estimate the optimal coupling position from each of the above distributions, and calculate the barycentric position of each optimal coupling position. After calculation, the optical fiber array can be easily set at that position.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing Embodiments 1 to 4 of the present invention. Figure 1 shows the basic configuration
Similar to FIG. 9 of the prior art, 1 is a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, 2 is an optical fiber array in which optical fibers corresponding to the respective semiconductor lasers are arranged in a line, and 3 is a semiconductor laser array 1 A collimator lens for converting the light emitted from the respective channels to parallel light, and 4 is an optical isolator for transmitting only light in one direction from the semiconductor laser array 1 to the optical fiber array 2 and suppressing return light,
Reference numeral 5 is a condenser lens for coupling the light emitted from the optical isolator 4 to the optical fiber array 2 for each channel, 6 is a thermistor which is a temperature detector for controlling the temperature of the semiconductor laser array 1, and 7 is the semiconductor laser array 1 and A chip carrier provided with the thermistor 6 and a feeder line 8 for supplying a current to the semiconductor laser array 1. FIG. 2 is a diagram illustrating the configuration of the optical isolator of FIG. 2A is a sectional view parallel to the optical axis of the optical isolator, and FIG. 2B is a sectional view perpendicular to the optical axis of the optical isolator (AA in FIG. 2A).
FIG. In the figure, 9 is a polarizer for converting incident light into linearly polarized light, 10 is a Faraday rotator for rotating the incident polarized light by 45 degrees, and 11 is a polarization of transmission by the Faraday rotator 10 with respect to a transmission polarization direction of the polarizer 9. An analyzer rotated by 45 degrees in the rotation direction, and 12 is a Faraday rotator 10.
Is a magnet for magnetizing, and 13 is a holder for holding the above-mentioned polarizer 9, analyzer 11 and magnet 12.

Example 1. FIG. 3 is a diagram for explaining a polarizer of an optical isolator showing a first embodiment of the semiconductor laser array module according to the first aspect of the invention. In the figure, 15 is 2
Bonding surfaces of the two prisms, 16 is an outgoing beam of the semiconductor laser array, 17 is an incoming surface of the outgoing beam 16 of the semiconductor laser array incident on the surface 15, 18 is a surface including the semiconductor laser array 1, 19 is an incident light beam, 20 is a P-polarized outgoing light beam, 21 is an S-polarized outgoing light beam, 22 is an arrow indicating the polarization direction of P-polarized light, and 23 is an arrow indicating the polarization direction of S-polarized light. The polarizer shown in FIG. 3 is a polarizing prism in which two prisms are bonded together, and transmits two orthogonal polarized lights, so there is no scattering from a holder or the like due to reflection of unnecessary polarization direction components to the side surface. Furthermore, since this polarizer does not contain fine metal fibers, there is no scattering by the fine metal fibers, so that an optical isolator without internal reflection can be obtained. The overall shape of the emitted beam of the semiconductor laser array incident on the polarizer is larger in the array direction as compared with the case of the single semiconductor laser, but smaller in the array vertical direction as in the case of the single semiconductor laser. The polarizer shown in FIG.
The incident surface of the emitted beam from the semiconductor laser array on the bonding surface is orthogonal to the surface including the semiconductor laser array. The polarization direction of the light emitted from the semiconductor laser array is S-polarized for the polarizer according to FIG. In the polarizer shown in FIG. 3, S-polarized outgoing light is emitted parallel to the incident light ray 19. That is, according to the polarizer of FIG.
The tilting direction of the bonding surfaces of the two prisms can be perpendicular to the array with a small beam shape, so that the polarizer can be made smaller and the optical isolator can be made smaller.

Example 2. FIG. 4 is a diagram for explaining a magnet of an optical isolator showing a second embodiment of the semiconductor laser array module according to the invention of claim 2. In the figure, 10, 1
2, 13 and 16 are the same as those in FIG.

As described above, in the case of the semiconductor laser array module, the shape of the beam incident on the optical isolator is longer in the array direction than in the array vertical direction of the semiconductor laser array. The magnet shape of the optical isolator shown in FIG. 4 has an effective diameter longer in the array direction than in the array vertical direction of the semiconductor laser array in accordance with the beam shape incident on the optical isolator. Therefore, the effective diameter of the magnets in the direction perpendicular to the array can be made as small as the effective diameter of the magnets of the optical isolator using a single semiconductor laser. As an example, the required magnet size is trial calculated under the same conditions as the conventional example. FIG. 4 shows the calculation result of the size of the magnet required when the emitted beam from a single semiconductor laser is φ1 mm and an effective diameter of 1 mm × 4 mm is secured by four elements. 4A is a cross-sectional view perpendicular to the optical axis of the optical isolator, and FIG.
FIG. 4 is a diagram (calculated value) showing a magnetic field strength distribution in the optical axis direction (Z direction) from the center of the magnet. In FIG. 4, the Faraday rotator 10 and the magnet 12 are the same as those in FIG.
Shows an emission beam from the same semiconductor laser as in FIG. The calculation condition of FIG. 4B is the residual magnetic flux density 1
Using 0k (Gauss) magnet material, magnet outer diameter 6mm
(W) x 3.2 mm (H) x 6 mm (L), hole shape 4 mm
(W) × 1 mm (H) × 6 mm (L) A magnetic field strength of 1500 (Oe) or more is obtained in the range of ± 1 mm with Z in the optical axis direction from the center of the magnet. As can be seen from this example, the size of the magnet in the direction perpendicular to the semiconductor laser array is half that of the conventional hollow cylindrical magnet shown in FIG.

Example 3. FIG. 5 is a diagram for explaining a magnet of an optical isolator showing a third embodiment of the semiconductor laser array module according to the present invention. In the figure, 9 to 13 are the same as in FIG. It goes without saying that the magnet of FIG. 5 also has a smaller cross-sectional area perpendicular to the optical axis than the circular one, and the same effect as that of the magnet of FIG. 4 can be obtained.

Example 4. FIG. 6 is a view for explaining a chip carrier of a semiconductor laser array showing a fourth embodiment of the semiconductor laser array module of the invention of claim 3.

In the chip carrier 7 shown in FIG. 6, the feeder line 8 to the semiconductor laser array 1 is connected to the semiconductor laser array 1 described above.
The thermistor 6 which is a temperature detector is placed on the left and right of the
Can be arranged near the rear surface of the semiconductor laser array 1. Therefore, the temperature of the semiconductor laser array 1 can be accurately measured, and the temperature control accuracy of the semiconductor laser array 1 can be improved. In this case, since the thermistor 6 is obliquely arranged with respect to the rear surface emission beam of the semiconductor laser array 1, the thermistor 6 is provided.
The rear surface emission beam hitting the semiconductor laser array 1 does not return to the semiconductor laser array 1 again,
The characteristics of the semiconductor laser array 1 are not deteriorated.

Example 5. 7A and 7B are views for explaining a position adjusting method of an optical fiber array showing a fifth embodiment of a method for assembling a semiconductor laser array module according to the fourth aspect of the invention.
FIG. 8 is a diagram illustrating a method for adjusting the position of the optical fiber array.
Is the continuation of. FIG. 8A is a diagram illustrating a method of adjusting the rotational position of the optical fiber array around the optical axis (Z). 8B and 8C illustrate a method for adjusting the position of the two axes perpendicular to the optical axis of the optical fiber array, that is, the axes of the optical fiber array corresponding to the coordinate axes (X, Y) of the semiconductor laser array. FIG. In FIG. 7, 25 is an image forming point of the semiconductor laser array, 18 is an array surface of the semiconductor laser array, 26 is an array surface of the optical fiber array, 27 is an angle formed by the two surfaces 18 and 22. is there. The coordinate system shown in FIG. 7 is the coordinate axis (X,
Y, Z), and the relative position adjustment of the optical fiber array corresponding to the semiconductor laser array is to align with the coordinate axes of the optical fiber array.

In FIG. 8, X _{1 to} X ₄ are optimum coupling positions in the X axis direction of CH ₁ to CH ₄ of the optical fiber, and Y _{1 to} Y ₄
Is the optimum coupling position in the Y-axis direction of CH1 to CH4, the black circle is the measured value of the coupled light output to the optical fiber, and the solid line is the optical fiber fitted with the measured value of the coupled light output to each channel by the Gaussian beam coupling theory. 2 is a theoretical curve of the distribution of the combined light output of. According to the Gaussian beam coupling theory,
Without adjusting the optical fiber to the optimum coupling position, the distribution of the coupling light output to the optical fiber can be estimated from the positions of several measurement points and the coupling light output, and the optimum coupling position of each optical fiber can be obtained. . As for the Gaussian beam coupling theory, there is Kenji Kono: “Basics and Applications of Optical Coupling Systems”, Hyundai Engineering Co., Ltd. (1991.1).

The necessary relative position adjustment of the optical fiber array is performed by referring to the reference coordinate axes shown in FIG. 7, the position in the optical axis direction (Z axis), two axes perpendicular to the optical axis, that is, the optical fibers. The positions are the array direction (Y axis) and the optical fiber array vertical direction (X axis), and the rotation position around the optical axis (Z axis). Of these, regarding the optical axis direction (Z axis) position,
Generally, the optimum position is different for each optical fiber of the optical fiber array, but since the position dependence of the combined optical output in the optical axis direction is small, a method similar to the method for the single semiconductor laser described in the section of the prior art is used. Can be used.

Next, adjustment of the rotational position around the optical axis (Z axis) will be described with reference to FIGS. 7 and 8A. The optical fiber array is moved in the array vertical direction (X axis) of the semiconductor laser array, and the coupled light output to each of the optical fibers at several points is measured, and as shown in FIG. 8A using the Gaussian beam coupling theory. Obtain the combined light output distribution to each optical fiber. Here, based on the optimum coupling positions X ₁ and X ₄ obtained from the coupled light output distributions of CH 1 and CH ₄ and the optical fiber spacing d of the optical fiber array, the array surface of the semiconductor laser array and the optical fiber array are calculated by the following equation. The two surfaces can be made parallel by determining the angle θ formed by the array surface and setting the rotation position around the optical axis at the position of θ = 0. θ = tan ⁻¹ ((X ₄ −X ₁ ) / 3d)

Next, the position adjustment in the two optical axis vertical directions (X axis, Y axis) will be described with reference to FIGS. 8B and 8C. First, the optical fiber array is moved (swept) in the array vertical direction (X axis) of the semiconductor laser array,
The coupled light output to each optical fiber is measured at several points, and the coupled light output distribution to each optical fiber as illustrated in FIG. 8B is obtained using the Gaussian beam coupling theory. In this case, CH
Although the combined light output distributions to the four optical fibers ₁ to CH4 are obtained, the position X _{1 of} CH1 and the position X _{4 of} CH4 are:
Since the array surface of the optical fiber is aligned so as to be parallel to the array surface of the semiconductor laser array by adjusting the rotation around the optical axis, they substantially match. However, CH2 position X ₂ and CH 3
The position X _{3 of} is generally X ₁ , due to the distortion of the coupling optical system.
Does not match X ₄ . Therefore, C is added to each of X _{1 to} X _4.
Multiplied by the weight of the coupling loss H1～CH4, it calculates the barycentric position of the X ₁ to X _4, to set the optical fiber array in position.

Next, the optical fiber array is moved (swept) in the array direction (Y-axis) of the semiconductor laser array, several points are measured for the coupled optical output to each optical fiber, and the coupling theory of the Gaussian beam is used for the measurement as shown in FIG. A combined light output distribution to each optical fiber as illustrated in (c) is obtained. Where CH1-C
H4 optimum coupling position Y ₁ to Y ₄ of generally not coincide with the distortion of the coupling optics. Therefore, each of Y _{1 to} Y is multiplied by the weight of the coupling loss of CH ₁ to CH ₄ , the position of the center of gravity of Y _{1 to} Y ₄ is calculated, and the optical fiber array is set at that position.

In the fifth embodiment, as the step of adjusting the relative position of the optical fiber array, position adjustment in the Z-axis direction,
The case of proceeding in the order of the rotation angle adjustment about the Z axis, the position adjustment in the Y axis direction, and the position adjustment in the X axis direction has been described.
The same effect can be obtained when the above steps are performed in the order of position adjustment in the Z-axis direction, rotation angle adjustment around the Z-axis, position adjustment in the X-axis direction, position adjustment in the Y-axis direction.

According to the above, each optical fiber of the above-mentioned optical fiber array is individually moved many times in two axes perpendicular to the optical axis and orthogonal to each other to move in the direction in which the combined light output becomes large, and the optimum coupling position is obtained. It is not necessary to search, and the position adjustment of the optical fiber array can be easily performed in a short time.

[0045]

As described above, according to the first aspect of the invention, as the polarizer on the incident side of the optical isolator, a polarizing prism in which two prisms are bonded to each other is used.
Since a polarizer that transmits two polarized lights is used, an optical isolator without internal reflection can be obtained, and a polarizer whose incident surface to the bonding surface of the incident beam is orthogonal to the surface including the semiconductor laser array can be obtained. Since it is used, the polarizer can be made small and the optical isolator can be made compact.
This makes it possible to obtain a small-sized semiconductor laser array module in which the emission frequency of the semiconductor laser is stable.

According to the second aspect of the invention, the size of the cross section perpendicular to the optical axis in the array vertical direction is adjusted in the array direction by matching the shape of the magnet of the optical isolator with the shape of the beam emitted from the semiconductor laser array. By making the size smaller than the size, the effective diameter of the magnet of the optical isolator having a single semiconductor laser can be made the same, and it is possible to suppress the size increase of the optical isolator in the array vertical direction due to the arraying of the semiconductor lasers. As a result, a compact semiconductor laser array module can be obtained.

According to the third aspect of the present invention, the feeder lines of the semiconductor laser array are arranged on the left and right sides of the semiconductor laser array, and the temperature detector is arranged near the rear surface of the semiconductor laser array. The temperature of the laser array can be measured accurately. The influence of the reflected return light from the temperature detector can be eliminated by arranging the temperature detector obliquely with respect to the beam emitted from the rear surface of the semiconductor laser array. This makes it possible to obtain a semiconductor laser array module whose oscillation frequency of the semiconductor laser is stable.

Further, according to the invention of claim 4, in the step of adjusting the rotational position of the optical fiber array about the optical axis and the position in the two axial directions perpendicular to the optical axis direction, the optical fiber array is set to a predetermined position. Sweep in the axial direction, measure the combined light output to multiple optical fibers at several points, estimate and obtain the distribution of the combined light output of each optical fiber, and calculate the optimum combining position to obtain the optimum combining position. Therefore, it is possible to obtain a method for assembling a semiconductor laser array module that can easily adjust the position without repeatedly moving the optical fiber array in order to obtain

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing first, second, third, and fourth embodiments of a semiconductor laser array module of the present invention.

FIG. 2 is a diagram illustrating a configuration of the optical isolator shown in FIG.

FIG. 3 is a diagram illustrating a polarizer of the optical isolator showing the first embodiment of the semiconductor laser array module of the present invention.

FIG. 4 is a diagram illustrating a magnet of an optical isolator showing a second embodiment of the semiconductor laser array module of the present invention.

FIG. 5 is a diagram illustrating a magnet of an optical isolator showing a third embodiment of the semiconductor laser array module of the present invention.

FIG. 6 is a diagram illustrating a chip carrier of a semiconductor laser array showing a fourth embodiment of the semiconductor laser array module of the present invention.

FIG. 7 is a diagram illustrating an optical fiber array position adjusting method showing a fifth embodiment of the method for assembling the semiconductor laser array module of the present invention.

FIG. 8 is a diagram illustrating an optical fiber array position adjusting method showing a fifth embodiment of the method for assembling the semiconductor laser array module of the present invention.

FIG. 9 is an overall configuration diagram showing a conventional semiconductor laser array module.

10 is a diagram illustrating a configuration of the optical isolator in FIG.

11 is a diagram illustrating a polarizer of the optical isolator in FIG.

12 is a diagram illustrating a magnet of the optical isolator in FIG.

13 is a diagram illustrating the semiconductor laser array of FIG.

[Explanation of symbols]

 1 Semiconductor Laser Array 2 Optical Fiber Array 3 Collimator Lens 4 Optical Isolator 5 Condenser Lens 6 Thermistor 7 Chip Carrier 8 Feed Line 9 Polarizer 10 Faraday Rotator 11 Analyzer 12 Magnet 13 Holder 14 Lochon Prism 15 Bonding Surface 16 Semiconductor Emitting beam of laser array 17 Incident surface of incident beam on bonding surface 18 Surface including semiconductor laser array 19 Incident light beam 20 P-polarized outgoing light beam 21 S-polarized outgoing light beam 22 P-polarized polarization direction 23 S-polarized polarization direction 24 electrode 25 imaging point of semiconductor laser 26 array surface of optical fiber array 27 angle formed by surface 18 and surface 26

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04B 10/28 10/02

Claims (4)

[Claims] 1. A semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, and an optical fiber array in which optical fibers corresponding to the respective semiconductor lasers are arranged in a line,
In a semiconductor laser array module having a lens system for optically coupling and an optical isolator for suppressing return light to the semiconductor laser, a polarizer on the incident side of the optical isolator is formed by bonding two prisms together. A semiconductor laser array module, characterized in that the polarizing prism is a polarizer that transmits two orthogonal polarized lights and has an incident surface on a bonding surface of an incident beam orthogonal to a surface including the semiconductor laser array. . 2. A semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, and an optical fiber array in which optical fibers corresponding to the respective semiconductor lasers are arranged in a line,
In a semiconductor laser array module having a lens system for optically coupling and an optical isolator for suppressing return light to the semiconductor laser, a magnet shape of the optical isolator is changed to a shape of a beam emitted from the semiconductor laser array. The semiconductor laser array module is characterized in that the size of the cross section perpendicular to the optical axis in the array vertical direction is made smaller than the size in the array direction. 3. A semiconductor laser array module comprising a semiconductor laser array in which a plurality of semiconductor lasers are arranged in a line, and an optical fiber array in which optical fibers optically coupled to each of the semiconductor lasers are arranged in a line. Power lines to the semiconductor laser array are arranged on the left and right sides of the semiconductor laser array, and a temperature detector is arranged in the vicinity of the rear surface of the semiconductor laser array and obliquely with respect to the rear surface emission beam of the semiconductor laser array. A semiconductor laser array module characterized by: 4. A method of assembling a semiconductor laser array module, comprising: a semiconductor laser array having a plurality of semiconductor lasers arranged in a row; and an optical fiber array having an optical fiber optically coupled to each semiconductor laser arranged in a row. In the method of assembling a semiconductor laser array module, the relative position of the optical fiber array is adjusted in the following steps: (1) First, the optical fiber array is moved in the optical axis direction to move the optical fiber array. The optical fiber array is arranged at a position where the coupled light output to the optical fiber array has a maximum value or a predetermined value. (2) Then, the optical fiber array is swept in the array vertical direction of the semiconductor laser array to Measure the combined optical output to multiple optical fibers at multiple points and calculate the combined optical output of each optical fiber. Estimate the distribution, determine the optimal coupling position of each optical fiber from the above distribution, the interval of the optimal coupling position of the optical fiber array at both ends of the optical fiber array or closest to both ends, and the interval of the corresponding optical fiber Then, the angle formed by the array surface of the semiconductor laser array and the array surface of the optical fiber array is obtained, and the angle formed by the two surfaces is adjusted to zero, and the angle around the optical axis of the optical fiber array is adjusted. Then, the optical fiber array is swept in the array vertical direction of the semiconductor laser array, the combined light output to the plurality of optical fibers of the optical fiber array is measured at a plurality of points, and the combined light output of each of the optical fibers is measured. Estimate the distribution, find the optimal coupling position of each optical fiber from the above distribution, give a predetermined weight to the optimal coupling position of each optical fiber, The center of gravity of the optimum coupling position of the fiber is obtained, and the position of the center of gravity is adjusted in the array vertical direction of the optical fiber array. (4) Next, the optical fiber array is swept in the array direction of the semiconductor laser array, The combined light output to the plurality of optical fibers of the optical fiber array is measured at a plurality of points, the distribution of the combined light output of each of the optical fibers is estimated, and the optimum coupling position of each of the optical fibers is obtained from the distribution, The optimum coupling position of each optical fiber is weighted in a predetermined manner to obtain the barycentric position of the optimum coupling position of each optical fiber, and the position of the optical fiber array in the array direction is adjusted to the barycentric position.