JPH01175785A - Semiconductor laser module with built-in optical isolator - Google Patents

Abstract

PURPOSE:To assure the title module of a flat package type wherein orientation of a polarization beam splitter is set with ease with set error and with a higher isolator ratio, by fixedly mounting the first polarization beam splitter on a chip carrier on which a semiconductor laser is fixed in alignment with the direction of polarization of the semiconductor laser. CONSTITUTION:The title module includes, in its flat package 206, a semiconductor laser 101, a lens 102, and a first polarization beam splitter 203 fixedly mounted on the same chip carrier 201 on which the semiconductor laser 101 is fixed or on a stationary bench for fixing the chip carrier, the fixation of the beam splitter being done in alignment with the direction of polarization of the semiconductor laser 101. In addition, the module includes interiorly and exteriorly of said package 206, a magneto-optical element 104 having polarization plane rotating power of 45 deg. and an optical isolator part in which the second beam splitter 204 is fixed at the angle of 45 deg. with respect to a direction of the polarization of the semiconductor laser 101 when the second beam splitter is inserted into a magnet 205 and with respect to the direction of rotation of the polarization plane of the magneto-optical element 104, and further a single mode optical fiber 209 for coupling the associated light and fixing the same.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a high quality semiconductor laser module with a built-in optical isolator for advanced optical communications using single mode optical fibers.

BACKGROUND OF THE INVENTION FIG. 3 is a longitudinal sectional view of a conventional semiconductor laser module with a built-in bullet-type optical isolator. The light emitted from the semiconductor laser 101 becomes collimated light by the microphotospheric lens 102,
After passing through a magneto-optical element 104 made of a YIG crystal placed in a magnet 103 and a polarizing beam splitter 105, a first lens 106 made of a self-focusing lens, and a second lens 106 made of a self-focusing lens,
The lens 107 serves as an optical system that focuses light onto the optical fiber wire 108 . Furthermore, in FIG. 3, 109 is an optical fiber core, 110 is an optical fiber cord, and 111 is a second optical fiber.
A fiber holder 112 fixes the lens 107 and the optical fiber 108, a lens holder 112 serves as a first lens holder, and a lens holder 113 fixes the fiber holder 111 to the lens holder 1.
A fiber holder fixing jig 114 is a monitor light-receiving element, which is moved on the optical axis and in a direction perpendicular to the optical axis to take optical coupling and then fixed. In the above configuration, the magneto-optical element 104 is saturated magnetized by the magnet 103 and 4
Hot polished with 5° Faraday rotation,
In addition, the polarizing beam splitter 105 is a magneto-optical element 10.
Semiconductor laser 10 whose polarization plane has been rotated by 45° by 4
The magneto-optical element 104 is adjusted and fixed at a position where the emitted light of the magneto-optical element 104 is rotated by 45 degrees in the Faraday rotation direction with respect to the emission polarization plane of the semiconductor laser 101, that is, the emitted light of the semiconductor laser 101 is transmitted to the maximum. Then, the return light from the optical fiber 108 is transmitted by a polarizing beam splitter so that only the linearly polarized light is transmitted through the magneto-optical element 10.
4, it is further rotated by 45 degrees and returns to the semiconductor laser 101 at an angle of 90" with the output linearly polarized light of the semiconductor laser 101. Due to the polarization characteristics of the semiconductor laser 101, induced noise due to the returned light is no longer generated. The output straight line of the semiconductor laser 101 Induced noise may be generated by returned light of polarized light perpendicular to the polarized light, and a polarizing beam splitter may be further added between the semiconductor laser 101 and the magneto-optical element 104.

Problems to be Solved by the Invention In such a conventional semiconductor laser module with a built-in optical isolator, the polarizing beam splitter 105 fixed to the magnet 103 and the magneto-optical element 104 are rotated and adjusted while monitoring the maximum power of transmitted light. There is a need to. Furthermore, even in the case where a polarizing beam splitter is added between the semiconductor laser 101 and the magneto-optical element, the maximum power of the polarizing beam splitter must be monitored and the rotation thereof adjusted and fixed. As described above, it takes a long time to adjust and fix the rotation of the polarizing beam splitter, and furthermore, there are problems in that setting errors are likely to occur, causing deterioration of the isolation ratio. Furthermore, in recent years, there has been a rapid increase in demand for flat packages that are easier to handle than bullet-type packages and have built-in Peltier elements and thermistors for cooling semiconductor lasers.

The present invention has been made in view of these points, and provides a semiconductor laser module with a built-in optical isolator that allows easy angle setting of a polarizing beam splitter in a flat package, and has less setting error (lower isolation ratio). .

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a semiconductor laser and a lens inside a flat-type dual-in-line package or a butterfly package, and a semiconductor laser fixed on the same chip carrier or on the same chip carrier. a first polarizing beam splitter fixed in accordance with the polarization direction of the semiconductor laser on a fixing table for fixing the chip carrier; and a magneto-optical element having a polarization plane rotation ability of 45 degrees inside or outside the flat package. an optical isolator section in which a second polarizing beam splitter is inserted into a magnet and fixed so that the second polarizing beam splitter forms an angle of 45° with the polarization direction of the semiconductor laser and the rotation direction of the polarization plane of the magneto-optical element; This is a semiconductor laser module with a built-in optical isolator equipped with a single-mode optical fiber that couples and fixes light. More preferably, the outer and inner shapes of the magnet are such that the angle of the second polarizing beam splitter can be set without adjustment, or
Only the first polarizing beam splitter, which is fixed with epoxy resin by sandwiching the magneto-optical element with the setting angle of the polarizing beam splitter set at 45°, is fixed on the chip carrier or on a fixing base that fixes the chip carrier. This is a semiconductor module with a built-in optical fiber insulator in which a magnet is inserted and fixed until the magneto-optical element functions.

Operation According to the present invention, with the above-described configuration and manufacturing method, the return light of the semiconductor laser is made 90' to the polarization direction of the semiconductor laser by the first polarizing beam splitter, and the error thereof is due only to mechanical precision. Further, the angle of the second polarizing beam splitter can also be set using only mechanical precision.

Embodiment FIG. 1a is a vertical cross-sectional configuration diagram showing an embodiment according to the present invention. Semiconductor laser 101 on chip carrier 201
．． The microlens 102 is fixed. The chip carrier 201 is fixed on the Peltier element 202, and the polarization direction of the emitted light from the semiconductor laser 101 is perpendicular to the surface of the Peltier element 202.

Therefore, the first polarizing beam splitter 203 is fixed on the surface of the Vertier element 202 in alignment with the polarization direction of the semiconductor laser 101. When fixing the semiconductor laser 101 and the chip carrier, if soldering is performed under pressure in order to reduce variations in the thickness of the solder, the angle setting error can be reduced to 0.5° or less. Next, in order to set the second polarizing beam splitter 204 in a polarization direction of 45 degrees with respect to the first polarizing beam splitter 203 with the magneto-optical element 104 in between, the second polarizing beam splitter 204 is set in a square or parallel plane as shown in FIG. magnet 205 with
Then, the second polarizing beam splitter 204 is adjusted to a set angle with respect to a hole or a certain surface having a set angle and fixed, and then that surface is placed against a surface such as the bottom surface of the package 206 and fixed.

Next, the light is focused by a lens 207 soldered to the side of the package 206, and an optical fiber 209, which is fixed to a ferrule 208 and polished diagonally to prevent reflection, is attached to a ferrule holder 210 in the optical axis direction and perpendicular direction. It is inserted and slid, the connection is removed, and it is fixed to the package 206 by YAG laser welding or the like.

Here, in order to reduce the setting error of the second polarizing beam splitter 204, the shape accuracy of the magnet 205 or the parallelism of the bottom surface of the package 206 with respect to the semiconductor laser 101 is required. If an increase in price is a problem in order to improve this accuracy, as shown in FIG. The first polarizing beam splitter 203 may be fixed on the Peltier element after measuring 45° or the isolation ratio and fixing it at the optimum position with an epoxy adhesive, and then inserting and fixing the magnet 205.

Further, FIG. 2 is a longitudinal cross-sectional configuration diagram showing another embodiment of the present invention. In this embodiment, a magnet 20 is installed outside the package 211.
5. Magneto-optical element 104. A second polarizing beam splitter 204 is provided, a magnet 205 holding part is provided in the package 211, and the magneto-optical element 1 is fixed to the magnet 205 within the holding part.
04, second polarizing beam splitter 204 and magnet 205
The magnet 205 and the magneto-optical element 10 rotate together.
4 is fixed and first fixed to the package 211, and only the second polarizing beam splitter 204 is rotated and fixed at an optimal position.

Further, the optical fiber 209 is fixed in the same manner as in the previous embodiment.

Effects of the Invention As described above, according to the semiconductor laser module with a built-in optical isolator of the present invention, it is possible to realize a module with a flat package that is easy to assemble and has a high isolation ratio with little setting error in the polarizing beam splitter during manufacturing.

[Brief explanation of the drawing]

FIG. 1a is a vertical sectional view showing a module according to an embodiment of the present invention, FIG. 1 is a plan view of a magnet used in the same module,
FIG. 1C is a sectional view of a main part of another module, FIG. 2 is a longitudinal sectional view of a module according to another embodiment of the present invention, and FIG. 3 is a longitudinal sectional view of a conventional semiconductor laser module with a built-in isolator. 101... Semiconductor laser, 102...
Microsphere lens, 104...Magneto-optical element, 11
4...Monitor light receiving element, 201...
Chip carrier, 202... Peltier element, 2
02,203...Polarizing beam splitter, 20
5...Magnet, 206.211...Package, 207...Lens, 208...
・Ferrule, 209...Optical fiber, 210
...Ferrule holder.

Claims (4)

[Claims] (1) A semiconductor laser and a lens are placed inside a flat dual-inline package or a butterfly package, and the polarization direction of the semiconductor laser is aligned on the same chip carrier on which the semiconductor laser is fixed or on a fixing table on which the chip carrier is fixed. a first polarizing beam splitter fixed to the flat package, a magneto-optical element having a polarization plane rotation ability of 45 degrees inside or outside the flat package, and a second polarizing beam splitter inserted into the magnet in the polarization direction of the semiconductor laser. and the second polarizing beam splitter 45 in the rotation direction of the polarization plane of the magneto-optical element.
A semiconductor laser module with a built-in optical isolator, which includes an optical isolator section that is rotated and fixed at an angle of .degree., and a single mode optical fiber that couples light and is fixed. (2) A semiconductor laser module with a built-in optical isolator according to claim 1, wherein the surface of the chip carrier for fixing the first polarizing beam splitter or the fixing base for fixing the chip carrier is parallel to the semiconductor laser chip fixing surface. . (3) The first and second polarizing beam splitters are fixed in advance with the magneto-optical element sandwiched between them so that they are at an angle of 45 degrees, and then the first polarizing beam splitter is placed on the chip carrier or a fixed base that fixes the chip carrier. A semiconductor laser module with a built-in optical isolator according to claim 1 or 2, wherein the semiconductor laser module has a built-in optical isolator. (4) When fixing the optical isolator inside a flat package, the second polarizing beam splitter has a magnet with a square outer shape or one side with a parallel surface, and is fixed at a 45° angle to that surface. 3. A semiconductor laser module with a built-in optical isolator according to claim 1 or 2, wherein the flat side of the magnet is fixed to a reference surface such as the bottom surface of a flat package.