Mach-Zehnder Interferometer, optical coupler, and manufacturing method of optical coupler

摘要

An optical coupler having a Y-branch operable to mix and output a first light and a second light from outside. The optical coupler includes: a first input optical wave guide operable to propagate the first light from outside; a second input optical wave guide operable to propagate the second light from outside; an optical coupler operable to output a mixed light, which is a mixture of the first light and the second light; and an output optical wave guide operable to propagate the mixed light and to output it from an end, wherein a width or a cross section area of said output optical waveguide is less than a width or a cross section area of an input optical waveguide.