Ultrafast all-optical logic gates with a quantum dot semiconductor optical amplifier by optical filtering

Abstract

Ultrafast all-optical logic gates are presented using an InAs/InP quantum dot semiconductor optical amplifier (QD SOA) with an Gaussian optical band-pass filter at around 1.55 m. Ultrafast carrier dynamics in the quantum dots are investigated for nonlinear cross-phase modulation which results in blue shift of signal light. The degree of blue shift induced by data pulses is utilized to realize optical logic gates such as AND, OR and XOR gate by appropriate adjustment of optical filter center. It is shown that spectral hole-burning and ultrafast carrier capture into QDs supports ultrafast logic gates, and high-differential gain in QDs may compensates for relatively week phase-modulation effects in QDs. The advantage of using data-pulse-induced blue shift is discussed, compared to the case of using data-pulse-induced red-shift, for ultra-high speed all-optical logic gates with pattern-effects reduced.