Abstract

Since the first report of biréfringent phase matching in isotropic GaAs,¹ there has been renewed interest in this class of materials for potential applications in various functional devices, ranging from second harmonic generation (SHG) structures to integrated devices for difference frequency generation, parametric oscillation and amplification and all-optical signal processing² Large second order nonlinear coefficients, broad infrared transparency range along with a mature fabrication technology, and the possibility of integration with semiconductor laser sources make these materials very attractive for optical frequency conversion applications. Phase matching in GaAs waveguide structures has been achieved using quasi phase matching (QPM)³ or artificial birefringence in stacked GaAs-oxidised AlAs (Alox) multi-layers. Although QPM is attractive, the high scattering losses presently limit the maximum attainable conversion efficiency in frequency conversion processes. Different second order processes including SHG, difference frequency generation (DFG)⁵ and parametric fluorescence (PF)⁶ have been successfully demonstrated in GaAs-based waveguides. Here we report efficient SHG in birefringent GaAs/Al₂O₃ waveguides at practical power levels using femtosecond fundamental pulses at 2.01 μm.

© 2002 Optical Society of America