Difference-frequency generation in AlGaAs Bragg reflection waveguides

We demonstrate Type II difference-frequency generation (DFG) around 1550 nm in AlGaAs Bragg reflection waveguides using a pump around 778 nm and a signal within the C-band range. Difference-frequency power of 0.95 nW was obtained using a pump power of 62.9 mW and a signal power of 2.9 mW. Nonlinear conversion efficiency was estimated to be 2.5 x 10(-2)%/W(-1) cm(-2) in a 1.5-mm-long sample. Using numerical simulations, the phase-matching bandwidth was predicted to be 100 nm, while the measured DFG showed no sign of bandwidth limitation across a wavelength span of 40 nm, which was limited by instrumentation.