Method and apparatus for wavelength conversion of signal light

摘要

A signal conversion device comprises a light source for emitting continuous wave (CW) light at a predetermined wavelength lambd, an optical element having a saturable absorption function, and a wavelength demultiplexing circuit for separating signal light at a desired wavelength from signal light outputted from the optical element. A threshold value for optical transmission and absorption of the optical element having the saturable absorption area is set to a level such that applied signal light at a wavelength lambds and the CW light outputted from the light source are absorbed at a light intensity level of either of the two lights, and are transmitted at a light intensity level of a total of the two lights.