Studies On The Optical Properties Of Niobic Tellurite Oxide Glass And Cyanine Thin Films

In recent years, considerable attention has been focused on nonlinear optical materials for their promising applications, including image processing, all-optical switching and optical storage memory. Nonlinear optical materials and devices have stimulated much interest.Today, a wide variety of materials are known to possess nonlinear optical properties. Among them, solid-state nonlinear materials including semiconductor materials, polymeric media and nonlinear optical glass are particularly attractive for their easy handling. Compared to other Materials, such as organic compounds and semiconductors, optical glass possesses a number of advantages, such as optical fiber coupling efficiency for nonlinear ivaveguide switches, mechanical stability, easy fabrication and lower cost, etc. has became one of the most potential nonlinear host materials, in despite of their relatively small optical nonlinearities. Simultaneously, the cyanine dye, which has been widely used in image process, photo-chemistry and laser technology, also gave arise to a great interest due to the large nonlinear susceptibility. Besides, the cyanine dye is easy to be shaped into thin film. Therefore, nonlinear optical glass and cyanine dye have become the two subjects of intense current researches.Among nonlinear optical glass, tellurium oxide (TeO₂)-based glass is more attractive due to their substantially higher figure of merit, relative higher third-order nonlinear optical susceptibility x³, ultra-fast response speed, extended infrared transmittance, good chemical resistance and low fusion temperature. TeO₂-Nb₂O₅-TiO₂ and lanthanide oxide doped TeO₂-Nb₂O₅-ZnO glass, show higher quality. Therefore, it is promising to serve as an ideal material for nonlinear optical devices.In the present dissertation, we systematically investigated structure dependence on the composition of the glasses, into the relationships of linear and nonlinear optical properties to the composition and structure of TeO₂-Nb₂O₅-TiO₂ and lanthanide oxide doped TeO₂-Nb₂O₅-ZnO glass by IR, Raman spectroscopes, DTA curves, transmittance spectroscopy, ellipjsometry and DFWM experiments. We also investigated the cause of multi-order diffraction and arrangement of molecule in cyanine thin film. The main results and conclusions are as follows: 1. In TeO₂-Nb₂O₅ -TiO₂ ternary system, the optical nonlinearity is caused bynonlinear electronic polarization. The third-order nonlinear optical susceptibility X(3) is determined by using the Degenerate Four-Wave-Mixing (DFWM) method (X(3)¹50xl0'13esu; Temporal response t=53ps) the coordination geometry of Te atoms is strongly dependent on the composition of the binary glass. Nb2Os content will work on crystallization behavior of glass. The addition of Ti4+ ions will change the coordination of Te from a [TeO4] trigonal bipyramid (tbp) into a[TeO3] trigonal pyramid (tp) through an intermediate polyhedra [TeCh+i], which will affect the glass stability, and w}ll also influence the linear and nonlinear optical properties.2. The third-order optical nonlineajities, including third-order nonlinear susceptibility #(3), nonlinear refractive index (nj) and temporal response, were measured with forward DFWM. The results show that EU2O3 doped 5ZnO-20Nb2O5-75TeO2 glass has large ti2 and ultra-fast temporal response. The higher the dopant concentration is, thje larger the nonlinear refractive ti2 and the faster the temporal response. The enhancement on third-order optical nonlinearities can be attributed to thje deformation of the electronic clouds in [TeO*}] enhanced by EU2O3 dopant.3. In TeO2-Nb2Os-ZnO glass, the dopent of lanthanide oxides, such as Dy2O3, LU2O3, will change the coordination of Te from a [TeO,*] trigonal bipyramid (tbp) into a [TeO3] trigonal pyramid (tp) through an intermediate polyhedra [TeCh+t], because of the large ligant field of Dy3+ or Lu3+ cations. The Ln3+ ions works as a bridge to connect with the neighbor tellurioum oxygen chains. As a result, the x(3) of Ln3+ ions doped Te...