The model of the optical switching center and the polarization anomalies in absorption spectra of cupric oxide after fast particles irradiation

We consider the model of the optical switching center—a system with the following properties: it has two (or more) metastable states |1〉, |2〉, separated by a potential barrier U; it can switch from one state to another by absorbing the photons with energy ?ω∼U; the transition |1〉→|2〉 is allowed only for a certain light wave polarization p₁ and the transition |2〉→|1〉—for other polarization p₂; these polarizations p₁, p₂ are orthogonal. The optical properties of this system are studied and are found to exhibit unconventional polarization dependence. In particular, the absorption spectrum observed in natural (unpolarized) light can display new features, that are absent in the spectra, obtained in two independent polarizations. We discuss these results in connection with the (yet unexplained) experimental findings N.N. Loshkareva, Yu.P. Sukhorukov, B.A. Gizhevskii, A.S. Moskvin, T.A. Belykh, S.V. Naumov, A.A. Samokhvalov, Phys. Solid State 40 (1998) 383], where the similar anomalous polarization dependence of the absorption spectra of cupric monoxide CuO after the fast particle bombardment is reported.