Abstract

The fastest recovery time (certainly <200 ps) of an optical NOR/AND gate at room temperature in a GaAs etalon is reported. This recovery time is at least an order of magnitude shorter than that for previous etalons consisting of GaAIAs/GaAs/GaA- IAs heterostructure. Our sample consists of 1.5-μm bulk GaAs and 0.25-μm GaAIAs, without a top GaAIAs window. A 2-D array of 10 × 10-μm GaAs pixels with 20-μm center-to-center spacing was defined by reactive ion etching. The array was sandwiched between high reflectivity (>90%) dielectric mirrors. Additionally, a somewhat longer recovery time was observed in a windowless GaAs etalon prepared from the same bulk crystal but without defining an array. The NOR gate contrast was 3-1 in both cases. The fast recovery is attributed to faster surface recombination of carriers at the GaAs-dielectric mirror interface compared with that at a GaAs-GaAIAs interface. The definition of windowless pixels, which limits diffusion and enhances recombination even further, should lead to arrays of small-volume ultrafast optical gates operating at several gigahertz rates.

© 1985 Optical Society of America