Nonlinear optical element

摘要

A nonlinear optical element is disclosed for reducing intensity noise of both mark level and space level, and being stable, miniaturized and low-priced. Signal light enters a semiconductor waveguide layer (14). The semiconductor waveguide layer (14) has a band gap wavelength shorter than a wavelength of the signal light. A diffraction grating (12), having a Bragg wavelength close to the wavelength of the signal light, is disposed adjacent to the semiconductor waveguide layer (14). DC voltage is applied to the semiconductor waveguide layer (14).