Study On Active Optical Properties And Structure Of Novel Chalcohalide Glasses

The thesis emphasizes on active optical properties of doped chalcohalide glasses, including the third-order nonlinearity properties, near-infrared (NIR) luminescence properties and upconversion (UC) visible luminescence properties. Besides, an effort is made to understand the structure of some typical chalcohalide glass involved above. The main results are shown as follows.AgI doped chalcohalide glass which has the higher linear refractive index than AgCl doped one shows the lower nonlinear refractive index. This is because while the presence of [GeS4-n/2Cl(Br, I)n] structural units makes a positive contribution to the enhancement of nonlinear refractive index, it is counterbalanced by the degradation effect on glass structure brought about by the addition of iodine. The theory which is derived in a two-level bond orbital approximation is found to fit the nonlinear refractive index of silver-halide modified samples more precisely than that widely applied to crystalline semiconductors. Thus, it is expected that this theory will serve as guidance for estimating the nonlinear optical properties of chalcohalide glass with limited knowledge of linear optical parameters.Tm3+-doped, Tm3+-Dy3+ and Tm3+-Dy3+-Bi codoped chalcohalide glass all show broadband NIR emissions. Especially for Tm3+-Dy3+-Bi codoped chalcohalide glass, it realizes a broadband emission almost covering the 1.2～1.5μm wavelength range. On the other hand, luminescence mechanisms are different in different systems. For the Tm3+-Dy3+-Bi codoped chalcohalide glass, realization of co-enhancement of Tm3+, Dy3+ and Bi emissions is due to the positive role of Bi ions as a media to promote the mutual energy transfer among them.Under an 808 nm laser pumped, both Tm3+-Ho3+ and Nd3+-Pr3+ codoped chalcohalide glass exhibit the enhanced UC luminescence. The Ho3+ luminescence is generated due to the energy transfer (ET) from Tm3+, while Nd3+ and Pr3+ transfer energy with each other in the chalcohalide glass.The structure of the Ge-In-S glasses is mainly composed of a network consisting of GeS4/2 tetrahedra and trigonal InS3/2 units. (S3/2Ge-GeS3/2)2+ ethane-like units bonded to InS4/2-tetrahedra form neutral sub-structures (or superclusters) which can be found dispersed in the network structure. The addition of AgI into the Ge-In-S glassy matrix brings about structural changes by introducing I atom which interrupt the glass network. Iodine enriches mainly the In species. The structure of trigonal and tetrahedral species and mixed-anion species InS2/2I, InS3/2I- and InS2/2I2- co-exist in the chalcohalide glass. Physical ageing is caused by structure relaxation in chalcohalide glass while chemical ageing is due to surface oxidation. Both physical and chemical ageing processes decrease microhardness.of glasses.