Observation of Optical Mixing Due to Conduction Electrons in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi></mml:math>-Type Germanium

Abstract

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 $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{\mathrm{p}}$ 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.