AlGaAs Semiconductor Quasiphase-Matched Wavelength Converters

Wavelength conversion based on sum frequency generation (SFG) using a semiconductor quasiphase-matched (QPM) waveguide with a periodically crystal domain inverted structure has been studied both theoretically and experimentally. Mathematical expressions with clear physical insight into QPM SFG are derived, taking into account waveguide propagation loss. SFG from AlGaAs QPM waveguides fabricated by a direct wafer bonding technique have been characterized. Nearly polarization insensitive wavelength conversion is demonstrated, and a normalized conversion efficiency of 810%/(W cm2) is obtained for a 0.5-mm-long waveguide with a propagation loss of over -100 dB/cm. The dependence of conversion efficiency and polarization sensitivity on device length is also discussed, and it is shown that the experimental results agree well with the theoretical simulations.