5.2–5.6-µm source tunable by frequency conversion in a GaAs-based waveguide

A tunable mid-IR source obtained by difference-frequency generation is demonstrated in a selectively oxidized GaAs–AlAs multilayer waveguide. We designed the waveguide to present the required form birefringence for phase matching of the nonlinear interaction. We took special care to lower losses for the mid-IR radiation. IR tunability from 5.2 to 5.6??µm was achieved by variation of the waveguide temperature and one pump wavelength. IR output power as great as 0.12 µW was obtained with the product of two pump powers of 7 mW2.?Losses of ?50 cm-1 were measured for the mid-IR radiation. These losses are attributed to surface scattering.