physica status solidi (b)
Nonlinear Polarisation of an Impurity Crystal
Evgenii Dmitrievich Trifonov, A. S. Troshin
Abstract
Abstract The polarization in a crystal containing impurities which is caused by the interaction with an electromagnetic field is given in terms of the Fourier transforms of the first‐order emission and absorption spectra due to the impurities. The results are obtained by means of the time‐dependent perturbation theory using the diagram technique. It is also shown that electron density matrix of the impurities satisfies the equations with two relaxation constants γ and Γ if the first‐order spectra are supposed to be of Lorentzian type.