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 percentage per unit length of emitting light being propagated in the output optical wave guide to a periphery of the output optical wave guide is higher than that of the first input optical wave guide or the second input optical wave guide.