χ(3)Nonlinear susceptibility in II–VI compounds and applications for squeezed light generation in semiconductors

We have measured the nonlinear refractive index near half-bandgap (Eg2) in ZnS and ZnSe by self-phase modulation experiments. The ratio of the nonlinear phase shift and the total optical absorption losses is critically dependent on the detuning from Eg2. Efficient quadrature squeezing was obtained at a centre wavelength of 780 nm in ZnS and at 960 nm in ZnSe. The scheme we employed can generally be applied to semiconductors, and opens the way for squeezed light generation over a wide range of wavelengths.