||M. B. Yairi, C. W. Coldren, D. A. B.
Miller, and J. S. Harris, Jr., "High-Speed, Optically-Controlled
Surface-Normal Modulator Based on Diffusive Conduction," Appl. Phys. Lett. 75
(5), 597-599 (1999)
We report a surface-normal optically-controlled
optoelectronic modulator made from a reversed biased p-i(multiple quantum well)-n
GaAs/AlGaAs structure with ultrathin barriers (5Å) whose recovery time is based on
diffusive conduction. Modulation of reflectivity from 0.3 to 0.6 and back again in about
50ps was demonstrated using a 750fJ control pulse at 855nm. We also demonstrated modulated
changes in power greater than the control pulse power -- a type of signal gain -- by a
factor of 1.8-to-1. Strong changes in reflectivity combined with low required control
power make this device potentially useful for high-speed switching arrays in such
applications as time division demultiplexing.
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