CuxS nanocrystals (NC’s) are reported. The samples are prepared by a CdS-to-CuxS chemical conversion from the glasses originally containing CdS NC’s. A room-temperature linear absorption of the converted samples shows several well resolved peaks with spectral positions from red to blue. These spectral features are explained by size quantization within CuxS NC’s (∼4 nm radius) with different copper deficiency [x is in the range from 1.8 (digenite) to 2 (chalcosite)]. A strong bleaching of the samples with a 3-ns relaxation is observed in the pump–probe measurements. A high value of the third-order nonlinear susceptibility (∼10−7 esu) is derived from the nonlinear transmission spectra.

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By using x-ray diffraction and optical waveguide characterization, it has been shown that proton-exchanged layers on Z-cut LiNbO(3) can have as many as seven different crystallographic phases that are stable at room temperature. This study allows us to establish some correlation between fabrication parameters and the crystalline structure, the index profiles, and the propagation losses of waveguides prepared by this process.

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