We present a systematic study of Ge(x)As(y)Se(1-x-y) bulk chalcogenide glasses to determine the best composition for fabricating all-optical devices. The dependence of physical parameters such as the band-gap, glass transition temperature and third order optical nonlinearity (n(2)) on composition has been studied and a relation between the bond-structure and elevated linear loss levels in high Germanium glasses has been identified. It is found that glasses with 11

Amorphous arsenic sulphide ͑As 2 S 3 ͒ films prepared by ultrafast pulsed laser deposition have been vacuum annealed at a range of different temperatures. Measurements of the glass transition temperature indicate that a crystallization process initiates at annealing temperatures around 170°C. In combination with Raman scattering analysis, we conclude that phase separation is intrinsic for our as-deposited films. During annealing two sorts of phase transformation are identified: one between different amorphous polymorphs, and another from the amorphous to a crystalline state. We point out a correlation between these two types of transformation and two characteristic time scales identified from measurements of the relaxation of the refractive index, and explain the Arrhenius and non-Arrhenius behaviors leading to the observed temporal characteristics.

Brillouin light scattering was used to obtain elastic and piezoelectric constants for a single domain orthorhombic KNbO3 single crystal at room temperature and pressure. More than 320 measurements of longitudinal and transverse acoustic wave velocities were obtained in 160 different crystallographic directions. An inversion of these data using the literature values for the dielectric permittivity of KNbO3 resulted in the full set of elastic and piezoelectric constants for the material. It is suggested that the difference between piezoelectric constants obtained by high- and low-frequency methods could be explained by the high-frequency relaxation-type dispersion for the dielectric constant ε33 in the GHz region by analogy with BaTiO3. The directional dependence of electromechanical coupling for longitudinal and transverse acoustic waves in KNbO3 was analyzed. The obtained elastic constants were (in GPa): CE11=224(4), CE22=273(5), CE33=245(5), CE44=75(1), CE55=28.5(5), CE66=95(2), CE12=102(5), CE13=182(10), CE23=130(6), where E denotes constant electric field strength.

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Amorphous Ge 33 As 12 S 55 films prepared by ultra fast pulsed laser deposition (PLD) have been vacuum annealed over a range of different temperatures. Raman scattering measurements indicated that the features corresponding to Ge-Se and As-Se clusters increase in intensity with increasing annealing temperature (T a ) up to their respective glass transition temperature, and then decrease with further increasing T a up to 300°C. Optical property measurements showed that the refractive index deceases but the optical band gap increases with increasing T a , and both of them could be fitted by the exponential function. The corresponding characteristic time extracted was found not to obey Arrhenius behavior, which is consistent with the existence of a broken network cut by cross-linking bonds and different clusters in films.