Optical isolator

Abstract

An optical isolator is constituted by providing a substrate, a waveguiding layer lattice-matched to the substrate, and a non-reciprocal phase shifter, and a waveguide and a curved waveguide for guiding the waveguiding layer are formed in the waveguiding layer, and a branch coupler is also provided therein, furthermore, a refractive index of the waveguiding layer is made larger than 3.36 by changing a semiconductor composition.

Description

technical field [0001] The present invention relates to an optical isolator with a miniaturized structure, and more particularly to changing the semiconductor composition of the waveguide layer lattice-matched to the substrate to increase the refractive index while reducing the allowable radius of curvature of the curved waveguide path, using a multimode interference type branch coupler Optical isolator with miniaturized structure to shorten the length of the device. Background technique [0002] An optical isolator is an element that allows light to pass in only one direction and blocks light traveling in the opposite direction. For example, after an optical isolator is provided at the output end of a semiconductor laser, light emitted from the laser passes through the optical isolator and can be used as a light source for optical fiber communication. Conversely, light to be incident on the semiconductor laser through the optical isolator is blocked by the optical isolator...

AI Technical Summary

Problems solved by technology

[0020] However, in the conventional optical isolator having the above-mentioned structure, the length in the direction (lateral direction) perpendicular to the light propagation direction is several to several tens of times (several μm to 100 μm) the width of the waveguide path (several μm). There is no big problem, but the element length (element length along the light transmission direction) becomes millimeter level, which is a big problem for the miniaturization of optical integrated circuits

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