Sub-picosecond all-optical switch using a multi-quantum-well semiconductor optical amplifier

We investigate an all-optical switch that is operated by the nonlinear phase-shift introduced by optical pulses with duration of 200 fs in a semiconductor optical amplifier (SOAs). The gate is made out of a commercially available InGaAsP–InGaAs multi-quantum-well (MQW) SOA placed in a Mach–Zehnder interferometer. We have measured the nonlinear phase-shift as a function of the injection current and we show that the largest effect takes place at zero current. We show that the gate has a contrast ratio better than 11 dB and that the switching time is less than 1 ps. The gate is operated with pulse energies of 800 fJ. 2004 Elsevier B.V. All rights reserved. PACS: 42.79.Sz; 42.79.Ta; 78.55.Cr; 78.47.+p