JPH02201314A - Optical isolator - Google Patents

Abstract

PURPOSE:To miniature the shape over the entire part and to decrease the number of parts and the adjustment points by integrating a lens and an element having the function of a Faraday rotor. CONSTITUTION:An LPE film 21 consisting of Bi garnet is grown on a gadolinium gallium garnet substrate 20 and a gadolinium gallium garnet substrate or lass substrate 22 is adhered onto the LPE film 21 of the Bi garnet. The optical element provided with the functions of the Faraday rotor and the lens in combination by working the laminate to a lens is used. Namely, the need for the conventional lenses on a light source side and an optical fiber side is eliminated by providing the Faraday rotor with the lens function. The miniaturizing and the decrease of the adjustment points are enabled in this way.

Description

[Detailed Description of the Invention] [Summary] Regarding optical isolators used in optical communication equipment, we have developed an LPE film of Bi garnet on a gadolinium gallium garnet substrate with the aim of reducing the number of parts, downsizing, and reducing the number of adjustment parts. After growing the LPE film and adhering a gadolinium gallium garnet substrate or a glass substrate onto the LPE film, a lens is processed to construct an optical element that has both a Faraday rotator and a lens function.

[Industrial application field]

The present invention relates to an optical isolator used in optical communication equipment.

Lasers used as light sources for optical communication become unstable when reflected light from the constituent devices of the optical communication system or the end face of the optical fiber returns. In order to eliminate the influence of this reflected light, an optical isolator is required near the light source.

[Conventional technology]

As shown in FIG. 3, a conventional optical isolator includes a laser light source 1, a lens 2, a polarizer 3, a Faraday rotator 5 having a permanent magnet 4, an analyzer 6, a lens 7, and an optical fiber 8 arranged in sequence in a straight line. Now, the light that comes out from the light source 1 and becomes polarized light by the polarizer 3 is polarized by the Faraday rotator 5, which changes the plane of polarization by 45"
be rotated. Since the reflected light from the optical fiber 8 is rotated by the Faraday rotator 5 by 45" in the same direction as the polarization plane, the polarization plane is rotated by a total of 90" and cannot pass through the polarizer 3. In this way, reflected light is prevented from returning to the light source 1.

[Problem to be solved by the invention]

The above-mentioned conventional optical isolator has a problem in that the number of parts is large, the overall shape is large, and the number of adjustment points is also large.

In view of the above-mentioned conventional problems, the present invention aims to reduce the number of parts, downsize the device, and reduce the number of adjustment points.

[Means to solve the problem]

In order to achieve the above object, the optical isolake of the present invention has a Bi
After growing a garnet LPE film 21 and adhering a gadolinium gallium garnet substrate or a glass substrate 22 on the Bi garnet LPE film 21, an optical element having both a Faraday rotator and a lens function is used by processing a lens. It is characterized by having been.

[For production]

By adding a lens function to the Faraday rotator,
Eliminates the need for conventional lenses on the light source side and optical fiber side,
It is possible to downsize and reduce the number of adjustment points.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.

In the figure, lO is a laser light source, and 11 is a lens 12.
, 12' and a Faraday rotator 13 are integrated; 14 is a permanent magnet that applies a magnetic field to the optical element;
15 is a polarizer, and 16 is an optical fiber, which are arranged as shown in the figure.

In this embodiment configured as described above, the Faraday rotator has a lens function, thereby eliminating the need for conventional condensing lenses on the light source side and the optical fiber side, resulting in miniaturization and fewer adjustment points.

FIG. 2 shows a method for manufacturing the optical element 11 used in the embodiment of the present invention.

First, on the GGG (gadolinium gallium garnet) substrate 20 shown in (a), (b) 4
Thickness that allows 5 degree Faraday rotation (for example, wavelength 1.3
When using a trm laser light source, Bi
A garnet LPE film 21 is grown. Next, as shown in the figure (C), GGG is placed on the Bi garnet LPE film 21.
After bonding the substrates or glass substrates 22 together using an optical adhesive, they are cut into dice using a guising tool as shown in figure (d), and then polished to form spheres as shown in figure (e). It is a lens-shaped optical element.

Further, during lens processing, the GGG substrates 20 and 22 may be polished and removed, and the Bi (Garnet) LPE film 21 may be processed into a lens shape.

The spherical lens can be processed using a well-known method, for example, as shown in FIG.
5 is placed, a dice-shaped material 26 is placed inside the ring, and a flat plate 28 with abrasive paper 27 pasted thereon is rotated, and the material 26 is rolled and polished until the plate 28 touches the ring 25. This allows it to be made into a spherical lens.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to integrate a lens and an element having the functions of a Faraday rotator, so that the overall shape of the optical isolator can be reduced, and the number of parts and adjustment points can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining a method for manufacturing an optical element used in an embodiment of the present invention, FIG. 3 is a diagram showing a method for processing a spherical lens, and FIG. FIG. 4 is a diagram showing a conventional optical isolator. In the figure, 10 is a laser light source, 11 is an optical element that integrates a lens and a Faraday rotator, 14 is a permanent magnet, 15 is a polarizer, 16 is an optical fiber, 20 is a GGG substrate, and 21 is a Bi garnet LPE film. , 22 indicates a GGG substrate or a glass substrate. Figure 22: GGG substrate or glass substrate Diagram illustrating the embodiment of the present invention Figure 1 Diagram illustrating the method for manufacturing a spherical lens

Claims (1)

[Claims] 1. A Bi garnet LPE film (21) is grown on a gadolinium gallium garnet substrate (20), and its B
An optical element (11) that has both a Faraday rotator and a lens function is used by bonding a gadolinium gallium garnet substrate or a glass substrate (22) on the i-garnet LPE film (21) and then processing the lens. Features of optical isolators. 2. The optical isolator according to claim 1, wherein the gadolinium gallium garnet substrate of the optical element (11) is removed and only the Bi garnet LPE film (21) is used as a lens.