2-PHOTON PHOTOCONDUCTIVITY IN SEMICONDUCTOR WAVE-GUIDE AUTOCORRELATORS

We study experimentally and theoretically the mechanism of photocurren t generation in GaAs/AlGaAs waveguide heterostructure diodes by pulsed and CW radiation over wide ranges of average incident power and waveg uide length. We confirm the importance of two-photon absorption in non -linear photocurrent generation and suggest that SHG mechanism is negl igible. We determine the dynamic range in which the diode has a quadra tic response to the incident optical peak power and hence is suitable for autocorrelation measurements of ultrashort optical pulses. (C) 199 8 Published by Elsevier Science B.V. All rights reserved.