Polarization-independent optical isolator

Abstract

An optical isolator for preventing reflection-returned light from entering back into the emitter of an optical system such as an optical fiber communication or an optical disc input/output device, using semiconductor laser. The polarization-independent optical isolator includes a light-emitting side optical fiber having a diameter of a core expanded to give a mode field diameter at an end face of 20 to 50 .mu.m, a light-incident side optical fiber having a diameter of a core expanded to give a mode field diameter at an end face of 20 to 50 .mu.m, and an optical isolator element provided between the light-emitting side optical fiber and the light-incident side optical fiber, said optical isolator element comprising a first polarization beam splitter located at a side of the light-emitting side optical fiber, a second polarization beam splitter located at a side of the light-incident side optical fiber, and a Farady rotator provided between the first polarization beam splitter and the second polarization beam splitter, and at least said first polarization beam splitter being a wedge type polarization beam splitter.

Dependencies are inferred from the claim text.