Abstract

Calculations of nonlinear response coefficients of semiconductors are plagued by unphysical divergences as the frequency of the incident light approaches zero. Such divergent contributions can often be easily understood and shown to vanish for the case of cold semiconductors. However, the fact that these divergent terms can be discarded in such cases is often not explicitly obvious and pan require the proper grouping of terms and the use of sum rules, a process that may be cumbersome for highorder non fin parities, in this paper we adopt a new formalism¹ that directly provides expressions for nonlinear response coefficients of cold semiconductors without the explicit appearance of such apparent divergences. Intrinsic to this formalism is an identification of distinct contributions to the crystal response that are associated with intraband and interband processes.

© 1993 Optical Society of America