Nonlinear optical and bistable properties of a wafer-fused vertical-cavity device based on InGaAsP

Abstract

We report on a detailed analysis of the nonlinear characteristics at 1.55 μm wavelength of a bistable device realised by wafer fusion of an InGaAsP InP heterostructure on an AlAs GaAs Bragg mirror. A sub-milliwatt threshold power and a switching contrast up to 70 : 1 have been obtained. The bistable behaviour has been observed over more than a 2.5 nm range. The carrier-induced dispersive nonlinearity of the InGaAsP active layer has been investigated, including the saturation behaviour of the nonlinear index change. A saturating value δn s = −3.1 × 10 −2 has been obtained at the wavelength corresponding to a linear absorption of 134 cm −1. The nonlinear refractive index cross-section is found in good agreement with a two-band absorption saturation model. Similarly, the switching thresholds are well described by a simple plane-wave model including nonlinear index saturation.