LIGHT SOURCE

摘要

A first optical waveguide guides a pumping light emitted from a semiconductor laser. A second optical waveguide absorbs the pumping light and emits a spontaneous emission light having a wavelength longer than that of the pumping light. A third optical waveguide guides a light output from the second optical waveguide to outside. A wavelength selecting element is provided between the second optical waveguide and the third optical waveguide, across which a resonator is formed between the semiconductor laser side and an output side to outside. A wavelength of a laser light emitted from the resonator is set by controlling length of the second optical waveguide.