Studies On The Optical Properties Of Optical Material

In this thesis, ultrafast optical properties for thin film materials and telluride glasses with Er2O3 dopant are main topics. Firstly, the studies on thin film materials and Er2O3-doped in telluride glasses are reviewed, and some determining methods and their applications are summaried.Secondly, the developments on the Sagnac interferometer for detecting the optical properties are reviewed, the experimental principle and setup for modified Sagnac interferometer are introduced, and the experimental conditions are discussed.Thirdly, the ultrafast optical properties of Au, Al, Ti, Si and TiO2 thin film measured by use of modified time-resolved Sagnac interferometer, and their mechanisms are discussed. The experimental results show that: For the metal thin film, the two sine peaks at the positive delay time derived from the two acoustic echoes caused by the reflect of the longitudinal coherent phonon between the metal film and the glass substrate interface, acoustic echoes derive from the reflect of the longitudinal acoustic wave caused by the thermoelastic field due to thermo-expansion, which spread along the free surface of the sample; and the longitudinal coherent phonon result from the coupling between refractive index and drawing force. Furthermore, as the time postpone, the intensity of the two peaks become smaller, the attenuation of the intensity is due to thermoreflectance. For the semiconductor thin film, the two sine peaks at the positive delay time derived from the two acoustic echoes caused by the reflect of the longitudinal coherent phonon in the semiconductor materials, and the longitudinal coherent phonon result from sudden shield of the surface space electric field. Furthermore, as the time postpone, the intensity of the two peaks become smaller.Fourthly, time-resolved four-wave mixing (DFWM) experiments in 75Nb2O5 -20TeO2 -5ZnO glasses doped by Er2O3 at different excitation intensities and latticetemperatures are performed. DFWM signal exhibits three peaks at high excitation intensities, where a main peak appears at zero time delay and two rather weak side peaks locate symmetrically at the negative and positive time delay, respectively. The main peak is attributed to local-field effect and two side peaks are attributed to Coulomb interaction.At last, the main results in this dissertation are summarized, and the possible future developments are discussed.