JPS6438719A - Optical isolator - Google Patents

Abstract

PURPOSE:To facilitate a light beam axial alignment, and to contrive to improve a forward insertion loss and an isolation by preventing a reflected return light from each element from returning onto an incident light beam, and offsetting a temperature characteristic and a polarization characteristic, so that a forward incident light and an emitted light become on the same straight line. CONSTITUTION:A forward light allows a normal light beam and an abnormal light beam to transmit through without varying them, and a reverse light repeats a conversion of the normal light beam and the abnormal light beam, so that they do not return onto an incident light beam. Also, directions of a magnetic field H applied to two pieces of Faraday elements 5, 6 are set to the reverse directions, so that even in case of a Faraday rotational angle is shifted from 45 deg. due to a temperature change, angles of portions which is shifted due to the temperature change are offset each other. Also, as for the forward light, an incident light to a double refraction body prism 1 and an emitted light from a double refraction body prism 4 are set on the same straight line. In such a way, a light beam axial alignment is facilitated, and a forward insertion loss and an isolation are improved.