JPS5666819A - Waveguide type magneto-optic photo circuit element - Google Patents

Abstract

PURPOSE:To obtain a nonantimetrical photo circuit element which is small in size, is stable and permits easy integration by changing the width of one of two sets of optical guides on a magneto-optic substrate having Faraday effect thereby forming the part where the equivalent refractive indexes of both guides are equal. CONSTITUTION:One guide 4 of optical guides 3, 4 of different thicknesses in proximity on a crystal substrate of garnet or the like having Faraday effect is changed of its width. Becase of this the equivalent refractive index of the guide 4 changes from the value smaller than the equivalent refractive index of the guide 3 up to the value larger than the same according to the widths, thus the part where the refractive indexes of the guides 4 and 3 are equal is formed. If the TE and TM mode rays propagating in the guides 3, 4 of different vibrating directions of the electric field of light are controlled by a magnetic field X, both rays couple at the part where the equivalent refractive indexes are equal or are propagated as they are. This part where the equivalent refractive indexes are equal is always formed even if it moves on account of temp. change etc. With this constitution, the nonantimetrical photo circuit element becomes small in size, stable and easy to integrate.