Low-loss orientation-patterned GaSb waveguides for mid-infrared parametric conversion

We design and demonstrate newcomers in the field of frequency down-converters based on quasi-phase matching: low-loss orientation-patterned gallium antimonide ridge waveguides suited to parametric conversion from pumping lasers around 2 µm to mid-infrared wavelengths around 4 µm. Thanks to careful control of the epitaxial growth conditions including low N-type doping and to an optimized dry etching process, losses as low as 0.7 dB/cm at 2 µm and 1.1 dB/cm at 4 µm are obtained.