Efficient second-harmonic generation in birefringently phase-matched GaAs/Al2O3 waveguides

We report efficient second-harmonic generation of femtosecond pulses in bir efringently phase-matched GaAs/Al2O3 waveguides pumped at 2.01 mum. By use of pump pulses of similar to 200-fs duration and type I interaction, practi cal second-harmonic average powers of up to similar to 650 muW were obtaine d, with an average input power of similar to 50 mW. Waveguides of four diff erent widths and two different lengths were investigated, and a normalized conversion efficiency of greater than 1000% W-1 cm(-2) was obtained for a 1 -mm waveguide. Measurements of pump and second-harmonic spectra provided cl ear evidence of phase matching and depletion of the pump spectrum. The meas ured bandwidth of the second harmonic was similar to1.3 nm. From the measur ements of transmitted pump power at the phase-matching wavelength, pump dep letions of more than 80% were recorded. (C) 2001 Optical Society of America .