Performance-limiting asymmetric distortion is observed in the spectra of fundamental pulses transmitted through GaAs–Al<sub>0.9</sub>Ga<sub>0.1</sub>As multilayer waveguides 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. Numerical simulations of the intensity-dependent spectra by use of the separately measured two-photon absorption coefficient are shown to be in good agreement with the observed spectra.
© 1999 Optical Society of America
Todd G. Ulmer, Ronson K. Tan, *Zhiping Zhou, Stephen E. Ralph, Richard P. Kenan, Carl M. Verber, and Anthony J. SpringThorpe, "Two-photon absorption-induced self-phase modulation in GaAs-AlGaAs waveguides for surface-emitted second-harmonic generation," Opt. Lett. 24, 756-758 (1999)