Piezobirefringence above the fundamental edge in Si

We report measurements of stress-induced birefringence in silicon in a spectral region (1.65 to 3.4 eV) where the material is opaque. A new technique that employs Raman scattering is used to extend the range of previous measurements performed in the transparent region below 1.2 eV. Theoretical fits to the data are made by considering the contributions to piezobirefringence due to the $E_1$, $E_1+{\Delta }_1$, and $E_2$ transitions under uniaxial stresses along the [001] and [111] directions.