Abstract

In recent years there has been much interest in all-optical switching in nonlinear semi-conductor waveguides, because of their potential for high-speed switching. To date much of the published work on all optical switching at wavelengths around 1.55 μm has concentrated on utilising the nonresonant Kerr nonlinearity in GaAs/AlGaAs structures.¹ Whilst these devices exhibit switching times of approximately 100 fs, they require peak optical powers of the order of a hundred watts to operate. This makes them unattractive for telecommunications applications due to the high powers required. We demonstrate here the use of the resonant bandfilling nonlinearity in an InGaAsP/InGaAsP Multiple Quantum Well (MQW) waveguide due to photo generated carriers to obtain switching at pulse powers, which can readily be obtained from an erbium amplified diode laser source. In order to produce gating a polarisation rotation gate was used, which relies on an asymmetry in the nonlinear refraction on the principle axes of the waveguide.² It has recently been shown that this nonlinearity can have a relaxation time as low as 18 ps.³

© 1994 IEEE