To improve a wavelength conversion efficiency and to stabilize a wavelength conversion operation.

This converter has a waveguide layer 11, which changes in the absorption intensity of incident light of a wavelength λp according to incident light intensity of a wavelength λs, between an n-type semiconductor substrate 10 and a p-type semiconductor layer 13, and is further provided with an optical absorption converter 1 which emits the signal light SG(λp) converted in the wavelength λP when continuous light CM(λp) of a wavelength λp and signal light SG(λs) of a wavelength 2s are made incident on the waveguide layer 11, a continuous light incident port for making the externally inputted continuous light CM(λp) incident on the optical absorption converter 1, and an optical circulator for externally emitting the signal light SG(λp) emitted from the optical absorption converter 1. The waveguide layer 11 of the optical absorption converter 1 has a multiple-quantum well structure formed by alternately laminating well layers 11a (11a-1 to 11a-4) having different band gaps and barrier layers 11b (11b-1-11b-5).