JPH04153619A - Optical isolator - Google Patents

Abstract

PURPOSE:To rationally manufacture the optical isolator which is reduced in size and uses a small number of components by using polarizing plates as a polarizer and an analyzer, and fixing one polarizing plate in the cylinder hole of a cylindrical magnet and fitting the other polarizing plate to an end surface of the cylindrical magnet through a holder in a rotational position adjustable state. CONSTITUTION:The cylindrical magnet 1 has a Faraday effect element 2, made of an LPE film, fixed at the center position in the cylinder hole, and the 1st polarizing plate 3 is fitted in the cylinder hole of the cylindrical magnet 1, and arranged and fixed at one side part of the Faraday effect element 2. Further, the ring type holder 4 has the 2nd polarizing plate 5 fitted and fixed in its inner peripheral part. The holder 4 fitted with the polarizing plate 5 is applied to the end surface of the cylindrical magnet 1, the angle of rotation of the holder to the cylindrical magnet 1 is adjusted in this state, and the holder 4 is fixed to the cylindrical magnet 1 after the adjustment. Consequently, the number of components is small and the size is reduced; and the assembly is facilitated and the price is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an optical isolator used in optical communication devices, disc players, etc. to prevent reflected light from returning to a semiconductor laser light source.

(Prior Art) Japanese Patent Laid-Open No. 118315/1983 discloses an optical isolator having the following configuration.

A Faraday effect element is fixed in a cylindrical hole of a cylindrical magnet, a polarizer and an analyzer are respectively attached to a cylindrical holder, and the polarizer holder and analyzer holder are joined to both end surfaces of the cylindrical magnet. Here, adjust the angle for attaching the Faraday effect element to the cylindrical magnet, the angle for attaching the polarizer and holder, the angle for attaching the analyzer and holder, and the angle for attaching the cylindrical magnet and both holders. , a polarizer, and an analyzer are arranged at appropriate inclinations with respect to the optical axis passing through them.

(Problems to be Solved by the Invention) A polarizing prism or a laminated polarizer is used as a polarizer and an analyzer in a conventional optical isolator, and the polarizer and analyzer are connected to a cylindrical magnet through a holder. As a result, the external dimensions of the optical isolator as a whole become large and the number of parts increases, making it impossible to miniaturize the optical isolator sufficiently to be combined with an extremely miniaturized semiconductor laser module. There was a problem that there were many parts and assembly was troublesome.

This idea was created in view of the conventional problems mentioned above, and its purpose was to rationally manufacture a compact optical isolator with a small number of parts suitable for combination with extremely miniaturized semiconductor laser modules. The goal is to make it possible.

(Means for Solving the Problem) Therefore, in the present invention, in an optical isolator consisting of a Faraday effect element fixed in both holes, and a polarizer and an analyzer arranged on both sides of the Faraday effect element, the polarizer and the analyzer each polarize light. One polarizing plate is fixed in both holes of the cylindrical magnet, and the other polarizing plate is attached to the end face of the cylindrical magnet via a holder whose rotational position is adjustable.

(Function) The external dimensions of the polarizing plates used as polarizers and analyzers can be made small relative to the effective diameter of the optical path, and one polarizing plate can be mounted in both holes of a cylindrical magnet without using a holder. Therefore, the dimensions of the optical isolator in the optical axis direction and in the direction orthogonal thereto can be made much smaller than in the past.

(Embodiment) FIG. 1 shows an optical isolator according to an embodiment of the present invention, and FIG. 2 is an exploded view thereof.

In both figures, 1 is a cylindrical magnet, and a Faraday effect element 2 made of an LPE film is fixed at the center of both holes of the magnet, and a first polarizing plate 3 is fitted into both holes of the cylindrical magnet 1. It is arranged and fixed on one side of the Faraday effect element 2.

Reference numeral 4 designates a ring-shaped holder, the outer diameter of which is approximately the same as that of the cylindrical magnet 1, and a second polarizing plate 5 is fitted and fixed into the inner peripheral portion of the holder.

The holder 4 with the polarizing plates attached is placed on the end face of the cylindrical magnet 1, and in this state, the rotation angle of the holder 4 with respect to the cylindrical magnet 1 is adjusted, and the first polarizing plate 3 and the second polarizing plate are Correctly adjust the angle formed by the polarization axis in step 5 to 45 degrees. After the adjustment, the holder 4 is fixed to the cylindrical magnet 1.

(Effects of the Invention) As explained in detail above, in this invention, a polarizing plate is used as a polarizer and an analyzer, so even if the effective diameter of the optical path is made large enough, the thickness and external dimensions of the polarizing plate is extremely small, which greatly contributes to miniaturization of optical isolators. In addition, one of the two polarizing plates is mounted inside the cylindrical magnet, and only the other polarizing plate is combined with the cylindrical magnet using a holder, which reduces the number of parts and makes the optical isolator more compact. In addition to being effective in
Assembly becomes easier, and the cost is reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical isolator according to an embodiment of the present invention, and FIG. 2 is an exploded sectional view of the same isolator. 1... Cylindrical magnet 2... Faraday effect element 3... First polarizing plate 4... Holder 5... Second Polarizing plate Figure 1 Figure 2

Claims (1)

[Claims] A Faraday effect element fixed in a cylindrical hole of a cylindrical magnet,
It consists of two polarizing plates as a polarizer and an analyzer arranged on both sides, one polarizing plate is fixed in the cylindrical hole of the cylindrical magnet, and the other polarizing plate is fixed in the cylindrical hole of the cylindrical magnet. An optical isolator characterized in that the optical isolator is attached to an end face via a rotationally adjustable holder.