Abstract

We report the first investigations of the photorefractive effect in a semiconductor on picosecond time scales. Because these times are too short for significant carrier-trap recombination to occur, here the space charge field is established between ionized donors and mobile free carriers, in contrast to the cw photorefractive effect where the space charge field is between ionized donors and traps. As a consequence, for picosecond pulses, the space charge field is limited by the number of available donors; whereas, for cw radiation the limiting field is determined by the density of traps. The former is believed to be an order of magnitude larger than the latter. Just as importantly, in the recombination-free regime, a significant space charge grating is achieved in a few picoseconds, compared to the tens-of-microseconds steady-state response time for the cw case¹. Our demonstration of picosecond photorefractive energy transfer clearly indicates that III-V semiconductors are promising for high-speed optical data processing and phase conjugation applications in the near infrared.

© 1986 Optical Society of America