Observation of Optical Mixing Due to Conduction Electrons inn-Type Germanium

This paper reports the first observation of the optical mixing due to conduction electrons in n-type germanium. The measured magnitude and anisotropy of the third-order susceptibilities are found to be in good agreement with the nonparabolicity effect calculated with a →k·→p method involving eight bands at the L point in the reciprocal lattice. It is concluded that the mechanism of momentum-dependent relaxation times contributes negligibly to the observed nonlinearity.