JPH05257106A - Optical coupler with polarization maintaining optical fiber - Google Patents

Abstract

PURPOSE:To obtain the optical coupler which can align the direction of the plane of polarization of the exit light of a semiconductor laser and the plane of polarization of a polarization maintaining optical fiber by arranging a magnetic garnet single crystal and an electromagnetic coil between two lenses and regulating the magnetic force of the electromagnetic coil, thereby rotating the plane of polarization of the light transmitted through the magnetic garnet single crystal. CONSTITUTION:The lens 2 converts the polarized light emitted from the semiconductor laser 1 to first parallel polarized light and the electromagnetic coil 4 applies the magnetic force to the magnetic garnet single crystal 3. The magnetic garnet single crystal 3 allows the transmission of the light emitted from the lens 2 and converts this light to the second parallel polarized light. The lens 5 condenses the light emitted from the lens 5 is made incident on the polarization maintaining optical fiber 6. The plane of polarization of the first parallel polarized light is rotated by regulating the magnetic force of the electromagnetic coil 4, by which the direction of the plane of polarization of the first parallel polarized light and the direction of the plane of polarization of the second parallel polarized light are aligned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical coupler with a polarization-maintaining optical fiber for efficiently inputting polarized light emitted from a semiconductor laser into a polarization-maintaining optical fiber.

[0002]

2. Description of the Related Art Next, the structure of a conventional optical coupler with a polarization maintaining optical fiber will be described with reference to FIG. In FIG. 2, 1 is a semiconductor laser, 2 and 5 are lenses, 6 is a polarization maintaining optical fiber, and 7 and 8 are holders. Holder 7 is semiconductor laser 1
And the lenses 2 and 5, and the holder 8 holds the polarization maintaining optical fiber 6. The polarized light emitted from the semiconductor laser 1 is converted into the first parallel polarized light by the lens 2 and the lens 5
And is output to the polarization maintaining optical fiber 6 whose polarization plane matches the polarization plane of the second parallel polarized light.

[0003]

In FIG. 2, in order to make the direction of the plane of polarization of the first parallel polarized light emitted from the semiconductor laser 1 and the direction of the plane of polarization of the polarization maintaining optical fiber 6 coincide, It is necessary to rotate the holding optical fiber 6 for axial alignment. According to the present invention, a magnetic garnet single crystal and an electromagnetic coil are arranged between the lens 2 and the lens 5, the magnetic force of the electromagnetic coil is adjusted to rotate the plane of polarization of the transmitted light of the magnetic garnet single crystal, and the first parallel polarization is obtained. Direction of polarization plane of wave light and second
It is an object of the present invention to provide an optical coupler with a polarization-maintaining optical fiber that matches the directions of the planes of polarization of parallel-polarized light.

[0004]

In order to solve this problem, in the present invention, a semiconductor laser 1 for emitting polarized light is used.
A lens 2 for converting polarized light emitted from the semiconductor laser 1 into first parallel polarized light; and a magnetic garnet single crystal 3 for transmitting the emitted light of the lens 2 and converting it into second parallel polarized light. An electromagnetic coil 4 for applying a magnetic force to the magnetic garnet single crystal 3, a lens 5 for converging the light emitted from the magnetic garnet single crystal 3, and a polarization maintaining optical fiber 6 on which the light emitted from the lens 5 is incident are provided. First adjust the magnetic force of the coil 4
The plane of polarization of the parallel-polarized light is rotated so that the direction of the plane of polarization of the first parallel-polarized light matches the direction of the plane of polarization of the second parallel-polarized light.

[0005]

Next, the construction of the optical coupler with the polarization maintaining optical fiber according to the present invention will be described with reference to FIG. 1 in FIG. 1 is a magnetic garnet single crystal, 4 is an electromagnetic coil, and others are in FIG.
Is the same as. That is, FIG. 1 is obtained by adding the magnetic garnet single crystal 3 and the electromagnetic coil 4 to FIG. The polarized light emitted from the semiconductor laser 1 is converted into the first parallel polarized light by the lens 2. At this time, the direction of the first parallel polarized light does not match the direction of the polarization plane of the polarization-maintaining optical fiber 6. The magnetic garnet single crystal 3 transmits the light emitted from the lens 2 into second parallel polarized light. Since the polarization plane of light transmitted through the magnetic garnet single crystal 3 is freely rotated by the magnetic force of the electromagnetic coil 4, the polarization plane of the second parallel polarized light is aligned with the polarization plane of the polarization maintaining optical fiber 6. be able to. The lens 5 collects the outgoing light of the magnetic garnet single crystal 4 and makes it incident on the polarization maintaining optical fiber 6.

[0006]

According to the present invention, the first lens and the second lens
The magnetic garnet single crystal and the electromagnetic coil are arranged between the lenses, and the magnetic force of the electromagnetic coil is adjusted to rotate the polarization plane of the transmitted light of the magnetic garnet single crystal. It is possible to match the directions of the polarization planes of the polarization maintaining optical fiber. Further, since the extinction ratio of the output light can be changed by changing the magnetic force of the electromagnetic coil, it is possible to use a variable extinction ratio light source with a polarization maintaining optical fiber.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical coupler with a polarization maintaining optical fiber according to the present invention.

FIG. 2 is a cross-sectional view of an optical coupler with a polarization maintaining optical fiber according to a conventional technique.

[Explanation of symbols]

 1 semiconductor laser 2 lens 3 magnetic garnet single crystal 4 electromagnetic coil 5 lens 6 polarization maintaining optical fiber

Claims (1)

[Claims] 1. A semiconductor laser (1) for emitting polarized light, a first lens (2) for converting polarized light emitted from the semiconductor laser (1) into first parallel polarized light, and a first lens (1) A magnetic garnet single crystal (3) that transmits the light emitted from the lens (2) and converts it into second parallel polarized light, and an electromagnetic coil that applies a magnetic force to the magnetic garnet single crystal (3)
(4), a second lens (5) that collects the light emitted from the magnetic garnet single crystal (3), and a polarization maintaining optical fiber (6) on which the light emitted from the second lens (5) is incident. And adjusting the magnetic force of the electromagnetic coil (4) to rotate the plane of polarization of the first parallel polarized light, and the direction of the plane of polarization of the first parallel polarized light and the plane of polarization of the second parallel polarized light. An optical coupler with a polarization-maintaining optical fiber, characterized by matching the directions.