Two-photon absorption-induced self-phase modulation in GaAs-AlGaAs waveguides for surface-emitted second-harmonic generation

Performance-limiting asymmetric distortion is observed in the spectra of fu ndamental pulses transmitted through GaAs-Al0.9Ga0.1As multilayer waveguide s designed for surface-emitted second-harmonic generation. This behavior is attributed to refractive-index changes resulting from the accumulation of free carriers created by two-photon absorption in the GaAs layers. Numerica l simulations of the intensity-dependent spectra by use of the separately m easured two-photon absorption coefficient are shown to be in good agreement with the observed spectra. (C) 1999 Optical Society of America.