JPH03107915A - Optical isolator - Google Patents

Abstract

PURPOSE:To prevent an adhesive swelling out to the light incident/emitting plane of a polarizing beam splitter, to improve working efficiency by facilitating assembling work, and to attain cost down by reducing member expenses by mounting the polarizing beam splitter on a semi-cylindrical holder, respectively. CONSTITUTION:A polarizer holder 25 and an analyzer holder 26 are formed in semi-cylindrical shape, respectively, and first and second polarizing beam splitters 23, 24 of rectangular parallelopiped shape are arranged at the holders 25, 26. And the polarizing beam splitters 23, 24 are mounted at the holders 25, 26 by applying the adhesive 27 to the two corner parts of the polarizing beam splitters 23, 24 and a part coming in contact with the end parts of the holders 25, 26. In such a way, it is possible to prevent the adhesive 27 swelling out to the light incident/emitting planes of the polarizing beam splitters 23, 24, and to improve the working efficiency by facilitating the assembling work, and also, to attain the reduction in cost down by reducing the member expenses.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to optical isolators. More specifically, the present invention relates to a device for preventing reflected light from the end faces of optical fibers, lens systems, and connectors in optical communications, writable video discs, etc. that use semiconductor lasers as light sources.

A conventional optical isolator has a magneto-optic crystal having a thickness that allows a Faraday rotation angle of 45° to be placed as a Faraday rotator between a polarizer and an analyzer whose polarization directions are arranged at 45° with respect to each other. The basic structure is that a permanent magnet for applying an external saturation magnetic field is placed around the magneto-optic crystal.

The principle of this optical isolator is shown in Figure 3 (a) and (b).
Shown below. FIG. 3 (IL) shows the polarization plane of light incident from the semiconductor laser. In FIG. 3 (IL), out of the light 2& incident on the polarizer 1, the linearly polarized light 2b that has passed through the polarizer 1 is rotated by 45 degrees by a rotator 3. This linearly polarized light 2G rotated by 45 degrees passes through a polarizer 1 and an analyzer 4 whose polarization directions are arranged at 45 degrees to each other, and is output as linearly polarized light 2d. On the other hand, FIG. 3(b) shows the state of the polarization plane of the reflected light from the end face of the optical fiber. Figure 3 (
In b), the linearly polarized light 6b that has passed through the analyzer 4 out of the reflected light 51L is determined in the direction of Faraday rotation only by the direction 6 of the magnetic field, regardless of the incident direction of the light, due to the non-reciprocity of Faraday rotation. is determined, so when the Faraday rotator 3 is adjusted, it undergoes an additional 45° Faraday rotation,
It is perpendicular to the polarization direction of the polarizer 1 and cannot pass through.

The configuration of a conventional optical isolator of this type is shown in FIG.

It looked like Figure 5. FIG. 4 is an assembled cross-sectional view of a conventional optical isolator, and FIG. 6 is an exploded perspective view of essential parts of a conventional optical isolator, in which 7 is a permanent magnet, 8 is a Faraday rotator, and 9 is a polarizer. 1 is a polarizing beam splitter, 10 is a second polarizing beam splitter serving as an analyzer, 11 is a polarizer holder, and 12 is an analyzer holder.

Here, the polarizing beam splitter is a cube made of two triangular prisms pasted together, and a multilayer dielectric pattern is formed on the surface of the pasted prisms, and the horizontally linearly polarized light 13 (hereinafter referred to as P wave) is transmitted as is, while the vertical It reflects linearly polarized light 14 (hereinafter referred to as S wave) in a direction 90° from the P wave emission direction.

Problems to be Solved by the Invention In such a conventional configuration, when fixing the first polarizing beam splitter 9 to the polarizer holder 11 and when fixing the second polarizing beam splitter 1o to the analyzer holder 12, Glue 16 into the gap between the inner surface of the hole of each holder 11.12 and the outer surface of each polarizing beam splitter 9.10.
However, because the gap is small, adhesive 1 is applied.
6 protrudes and adheres to the light input/output surfaces of the polarizing beam splitters 9 and 1o, causing deterioration of the characteristics of the optical isolator, and requires careful work, which is very time-consuming. was there.

The present invention solves these problems by preventing the adhesive from protruding onto the light input/output surface of the polarizing beam splitter.
It also aims to make work easier and improve work efficiency, as well as reduce the total cost of parts and materials.

Means for Solving the Problems In order to solve this problem, the present invention has a first and second polarizing beam splitter attached to semi-cylindrical polarizer and analyzer holders, respectively.

Function: According to this configuration, since the polarizing beam splitter is attached to each semi-cylindrical holder, the adhesive is prevented from protruding onto the light input/output surface of the polarizing beam splitter, facilitating assembly work and improving work efficiency. It is possible to improve this, reduce component costs, and reduce costs.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of essential parts of an optical isolator according to an embodiment of the present invention, and FIG. 2 is an assembled sectional view of the optical isolator according to an embodiment of the present invention. In FIGS. 1 and 2, the polarizer holder 25 and the analyzer holder 26 are each made into a semi-cylindrical shape, and the holder 25.2
The first and second polarizing beam splitters 23 and 24 each having a rectangular parallelepiped shape are arranged on the holder 25 as shown in FIG.
．． Each polarizing beam splitter 23, 24 is attached to each holder 25, 26 by applying an adhesive 27 to the portions (adhesive applied portions) in contact with both ends of the polarizing beam splitter 26. A polarizer holder 2 is placed on both sides of the permanent magnet 210 in which the Faraday rotator 22 is inserted into the cylindrical portion thereof, so that the polarization directions of the first polarizing beam splitter 23 and the second polarizing beam splitter 24 are different from each other by 45 degrees.
6 and the analyzer holder 26, and place them and the permanent magnet 2.
The optical isolator is assembled by gluing the first and second connection surfaces together. Also, in Figure 2, 28 is horizontally linearly polarized light (
29 indicates vertically linearly polarized light (S wave).

Effects of the Invention As described above, according to the present invention, each polarizing beam splitter is attached to a semi-cylindrical holder, thereby preventing the adhesive from protruding onto the light input/output surface of the polarizing beam splitter. Further, it is possible to facilitate assembly work and improve work efficiency, and also to reduce component costs and costs.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of essential parts of an optical isolator according to an embodiment of the present invention, Fig. 2 is an assembled sectional view of an optical isolator according to an embodiment of the invention, and Fig. 3 1b shows the principle of the optical isolator. FIG. 4 is an assembled sectional view of a conventional optical isolator, and FIG. 6 is an exploded perspective view of a main part of the conventional optical isolator. 21... Permanent magnet, 22... Faraday rotator, 23... First polarizing beam splitter, 24... Second polarizing beam splitter, 2
6...Polarizer holder, 26...Analyzer holder, 27...Adhesive.

Claims (1)

[Claims] A first polarizing beam splitter and a second polarizing beam splitter whose polarization directions are arranged at 45 degrees to each other, a Faraday rotator located between the first and second polarizing beam splitters, and a periphery of the Faraday rotator. 1. An optical isolator comprising: a cylindrical permanent magnet provided at a portion of the optical isolator; and wherein the first and second polarizing beam splitters are respectively attached to a semi-cylindrical polarizer and an analyzer holder.