ENCODER AND ITS MANUFACTURE

摘要

PURPOSE: To provide an encoder an optical waveguide of which has a function of a lens and which is highly-integrated, compact and applicable to various semiconductor lasers, with a process of forming a 90 deg. phase shift film eliminated. CONSTITUTION: A semiconductor laser 1, a film-like optical waveguide 3 and a photodiode 2 at a position interfering a diffraction light, are formed on the same substrate. A step difference 36 having an optical path difference of (1/4 + an integer) times a light wavelength is provided at half an end face of the waveguide of the opposite side to the semiconductor laser 1.