Speed enhancement in a photorefractive multiple-quantum-well modulator by pulsed illumination

A factor-of-four increase in the operating speed of a high-resolution low-t emperature-grown photorefractive multiple-quantum-well (PRMQW) spatial ligh t modulator is reported. This is achieved by shining a spatially uniform er asing pulse from a light-emitting diode (LED) on the device that is driven by a single-sided applied voltage. The erasing pulse is turned on briefly d uring the off-voltage cycle while a grating is written during the on-voltag e cycle using a continuous-wave laser diode. The dependence of the change i n diffraction efficiency on the frequency of the applied voltage, on the ti ming and duration of the LED pulse, and on the intensities of the LED and o f the pump beams has been investigated. Our results are relevant to applica tions of PRMQW modulators where both high spatial resolution and fast opera ting speed are required. (C) 2001 American Institute of Physics.