Role of χ⁽³⁾ anisotropy in the generation of squeezed light in semiconductors

We have measured the real n₂ and imaginary β parts of the χ⁽³⁾ nonlinear susceptibility in polycrystalline ZnS and ZnSe and its anisotropy σ in cubic ZnSe near half-band-gap using femtosecond spectroscopy. We obtain values in good agreement with recent studies. The dispersion of n₂ and β in polycrystalline ZnSe is compared with two- and four-band model calculations. The dispersion of n₂ and β strongly affects the pulse transmission through thick samples, and has been included in a model that describes the pulse spectrum after self-phase modulation. The χ⁽³⁾ nonlinearity allows for both self-phase modulation and cross-phase modulation, and we demonstrate that both effects can efficiently generate squeezed light in semiconductors by four-wave mixing. © 1996 The American Physical Society.