The effectiveness of surface recombination in speeding up the relaxation of a GaAs eacute;talon is reported. Various thickness (1.5, 0.5, 0.3, 0.13 mgr;m) bulk GaAs windowless samples were fabricated and tested as optical logic gates. Times for complete recovery of transmission lie between 400 and 30 ps. The response shows a roughly linear increase in speed as the sample thickness decreases, consistent with surface recombination being the dominant relaxation mechanism. A very fast cycle time of 70 ps is demonstrated using a 0.3hyphen;mgr;mhyphen;thick windowless GaAs eacute;talon as an allhyphen;optical logic device. Protonhyphen;bombarded samples show slower recovery and poorer contrast, and they require more gating energy.
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