JPS62150210A - Semiconductor laser and optical fiber coupling module with optical isolator - Google Patents

Abstract

PURPOSE:To obtain a small-sized semiconductor laser and optical fiber coupling module with optical isolator which does not require any optical parts, by reflecting S-component polarized light only of the light propagated through an optical fiber in the opposite direction with a polarization beam splitter and providing a lens which condenses the reflecting light into a photodetecting element. CONSTITUTION:Of the signal light propagated through an optical fiber 4 in the opposite direction, only the S-component polarized light is reflected in the direction vertical to the optical axis by means of a polarization beam splitter 7 and condensed into a photodetecting element 27 by a lens 26. The lens 26 is fixed at the inside of a polarizer holder 28 and the polarization beam splitter 7 is fixed at the inside of the polarizer holder 28 at the position where reflecting light comes out to a rod lens 26 side. The polarizer holder 28 has a structure which can be rotated on a magnet holder 9 and is fixed by bonding or welding at the position, at which the holder 28 has a structure which can be rotated on a magnet holder 9 and is fixed by bonding or welding at the position, at which the holder 28 can exert the function of an optical isolator. The photodetecting element 27 is fixed by bonding or welding at the position where the element 27 can receive signal light together with a photodetecting element holder 29 after fine adjustment. The optical fiber 4 is optically coupled with the polarization beam splitter 7 at the position about 1-2mm above the splitter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor laser/optical fiber coupling module with an optical isolator used as a light source for optical communication and optical signal transmission in optical fiber sensors and the like.

2. Description of the Related Art FIG. 3 shows a vertical cross-sectional view of a conventional semiconductor laser/optical fiber coupling module with an optical isolator, which is basically based on a concentric cylindrical shape. The light emitted from the semiconductor laser 2 fixed on the package stem 1 is transmitted through a lens 3 to an optical fiber 4.
The light is focused on. The magneto-optic crystal 6 is capable of rotating linearly polarized light by 45 degrees using a magnet 6. Further, the polarizer 7 is fixed to a polarizer holder 8, and is fixed to a magnet holder 9 so that the polarization plane of the light emitted from the semiconductor laser 2 is aligned with the polarization direction of the polarized light rotated by 45 degrees by the magneto-optic crystal 5. . As the polarizer 7, a polarizing film, a polarizing beam splitter, etc. are used. 1o is a lens mount, 11 is an electrode, 1
2 is a phenol holder, and 13 is phenol.

Such a semiconductor laser/optical fiber coupling module with an optical isolator can eliminate the reflected return light to the semiconductor laser, eliminating instability in the oscillation operation of the semiconductor laser due to the return light, making it possible to realize a high-quality transmission system. It is.

FIG. 4 shows an example of a transmission system using a light source as mentioned in the conventional example. FIG. 4 (IL) shows the Pockels element 14
This is an example of a conventional example of an optical fiber applied voltage system using an optical fiber. Light from a light source consisting of a module 15 as shown in FIG. 3 is transmitted through a polarization-maintaining optical fiber 16 (4 in FIG. 2), and the information phase-modulated by a Pockels element is converted into the same polarization-maintaining light by a mirror 17. The signal is returned to the fiber 15, reflected by the half mirror 18, applied with an optical bias by the wavelength plate 19, and further converted from phase modulation information to optical intensity modulation information by the polarizer 20, and extracted as a sensing signal by the light receiving section 21. FIG. 4(b) is a block diagram of optical fiber bidirectional communication. Light source 16λ.

The two optical signals emitted from the respective optical fibers 16b and propagating in opposite directions through the optical fiber 23 (4 in FIG.
6-&, 25-b.

Problems to be solved by the invention A semiconductor laser with an optical isolator as shown in FIG.
When the optical fiber coupling module 15 is used as a light source for a conventional transmission system as shown in FIG. 4, a half mirror 1 polarizer, a directional coupler, etc. are required outside the module.

The present invention has been made in view of the above points, and is suitable for use in transmission systems that require a half-mirror-1 polarizer, directional coupler, etc. outside of a semiconductor laser/optical fiber coupling module with an optical isolator. The purpose of the present invention is to provide a compact semiconductor laser/optical fiber coupling module with an optical isolator that does not require an optical isolator.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
A semiconductor laser/optical fiber coupling module with an optical isolator consisting of a semiconductor laser, a lens for condensing the emitted light from the semiconductor laser onto an optical fiber, a magneto-optic crystal, a magnet, and a polarizing beam splitter. It is equipped with a lens that reflects only the S-component polarized light of propagating light by a polarizing beam splitter and focuses the reflected light on a light receiving element.

According to the above-described configuration of the present invention, the polarizing beam splitter, which is an internal component of the semiconductor laser/optical fiber coupling module with optical isolator, can be used as a half mirror 9 polarizer, a directional coupler, etc. It is possible to reduce the number of optical components in the system.

Embodiment FIG. 1 is a vertical sectional view for explaining a semiconductor laser/optical fiber coupling module 100 with an optical isolator in one embodiment of the present invention. Of the signal light propagating in the opposite direction through the optical fiber 4, only the S component polarized light is reflected in a direction perpendicular to the optical axis by the polarization beam splitter 7, and is focused onto the light receiving element 27 by the lens 26. Lens 26 is polarizer holder 2B
The polarizing beam splitter 7 is fixed inside the polarizer holder 2 at a position where the reflected light is emitted to the rod lens 26 side.
It is fixed within 8. The polarizer holder 28 has a structure that can be rotated on the magnet holder 9, and is fixed by adhesive or welding at a position where it functions as an optical isolator. Further, the light receiving element 2a is finely adjusted to a position where it can receive the signal light together with the light receiving element holder 29, and is fixed by bonding or welding.

The optical fiber 4 is 1 to 2M above the polarization beam splitter 7.
Optical coupling is performed at a position of about M, and the light that is emitted from the optical fiber 4 in the opposite direction at this distance and reflected by the polarizing beam splitter 7 with a two-blade angle is passed through a lens 26 with a length of about 0.2 pitch. It can be coupled to the light receiving element 27 without loss.

A semiconductor laser with an optical isolator as shown in Figure 1
When the optical fiber coupling module 100 is used, FIG.
The optical fiber applied voltage sensor shown as L) is shown in Figure 2 (+!
The configuration shown in L) is obtained, and the number of parts can be reduced. The optical fiber bidirectional communication system shown in FIG. 4(b) has a configuration as shown in FIG. 2(b), and uses polarization-maintaining optical fibers 16 as optical fibers to transmit signals using mutually perpendicular polarization axes. If used as a transmission path, a bidirectional optical fiber communication system will be possible with a simple configuration. 100 &, 1
00b is the light source of the module shown in FIG. 1, and 7J 7b is a polarizing beam splitter.

Effects of the Invention As described above, according to the semiconductor laser/optical fiber coupling module with an optical isolator according to the present invention, it is possible to omit optical components such as a half mirror 9 polarizer and a directional coupler in a transmission system. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor laser/optical fiber coupling module with an optical isolator according to an embodiment of the present invention. R
Figure 2 is a diagram for explaining the transmission system using the semiconductor laser with optical isolator/optical fiber coupling module in this embodiment, and Figure 2 (&) is a configuration diagram of the optical fiber applied voltage sensor. Figure (b) is a configuration diagram of a system in which two-way optical fibers are connected, Figure 3 is a cross-sectional view of a conventional semiconductor laser with optical isolator/optical fiber coupling module, and Figure 4 is a diagram of a conventional semiconductor laser with optical isolator/optical fiber. FIG. 4(a) is a configuration diagram of an optical fiber applied voltage sensor, and FIG. 4(b) is a configuration diagram of an optical fiber two-way communication system. . 2... Semiconductor laser, 3... Lens,
4...Optical fiber, 6...Magneto-optical element, 6...Magnet, 7 (7a, 7b)・mountain・
・Polarizing beam splitter, 14...Pockels element, 16...Polarization maintaining optical fiber, 24...
...Directional coupler, 26 ... Lens, 27
...... Light receiving element, 28... Polarizer holder, 29... Light receiving element holder, 1002L, 10
0b...Light source. Name of agent: Patent attorney Toshio Nakao and 1 other person2-
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Claims (4)

[Claims] (1) A semiconductor laser/optical fiber coupling module with an optical isolator, which includes a semiconductor laser, a lens for guiding light emitted from the semiconductor laser to an optical fiber, a magneto-optic crystal, a magnet, and a polarizing prism, A semiconductor laser/optical fiber coupling module with an optical isolator, comprising a lens that focuses reflected light of only S-component polarization of light traveling backward through the optical fiber toward the module side onto a light receiving element using a polarizing prism. (2) The semiconductor laser with an optical isolator according to claim 1, wherein the optical fiber is a polarization maintaining optical fiber.
Fiber optic coupling module. (3) A semiconductor laser/optical fiber coupling module with an optical isolator according to claim 1 or 2, which comprises a Pockels element at the output end of a polarization-maintaining optical fiber. (4) The semiconductor laser with optical isolator/optical fiber coupling module according to claim 1 or 2, which comprises a semiconductor laser/optical fiber coupling module with an optical isolator at the output end of the polarization-maintaining optical fiber.