Nonlinear optics of semiconductor-doped glasses

Nonlinear optical properties of semiconductor-doped glasses are reviewed. A growth technique enabling to obtain semiconductor microcrystals with controlled sizes grown in a glassy matrix is described. It is shown that the optical properties of such systems are determined by the energy spectrum of the electron-hole pairs confined in the small-size microcrystals. The dependences of these spectra on the microcrystal size are analysed. The effect of the blue-shift of the spectra occurring at high excitation levels is discussed. A excitation with light of photon energy below the energy gap of the glass photoionization is discovered. In this process the electron is ejected from the microcrystal to the glass where it is captured by the long-lived centers. The latter process is likely to explain the effect of the glass darkening and the formation of permanent volume grating. (author)