Abstract
Recent progress of semiconductor-based quasi-phase-matching (QPM) wavelength conversion devices is reviewed.Compound semiconductors are promising materials for generating coherent light in the mid-infrared (IR) region because of their transparencies in the long-wave IR range and high second-order nonlinearities.Bulk-type and waveguide-type QPM devices have been developed using Ga As, and their high potentials are now being demonstrated. Wider-bandgap semiconductors are also studied as materials for the next-generation wavelength conversion devices.