Shaoxuan Gu

Optical second-order nonlinearity of the infrared transmitting 82GeS2∙18CdGa2S4 nanocrystallized chalcogenide glass

The infrared (IR) transmitting nanocrystallized chalcogenide glass only containing α-CdGa2S4 IR nonlinear optical crystallites, which were confirmed by x-ray diffraction and Raman scattering measurements, was fabricated through the controllable nucleation and crystallization of the glass with the composition 82GeS2∙18CdGa2S4 at a temperature of 325°C far below the glass transition temperature (Tg:415°C) for a long duration. A clear second harmonic generation (green light, 532nm) could be observed in the transparent 82GeS2∙18CdGa2S4 nanocrystallized chalcogenide glass, demonstrating the IR frequency-doubling function of the prepared nanocrystallized composite material.

Laser-induced phase transformation in chalcogenide glasses investigated by micro-Raman spectrometer

A 488 nm continuous wave (CW) laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and crystallization were observed at laser-irradiated region in GeS2-Sb2S3 glasses. The composition dependence of laser-induced phase transformation was discussed in terms of thermal stability and microstructural modification. It is strongly suggested from these results that fabrication of passive and active chalcogenide glass waveguides, such as refractive index change and nonlinear optical crystal line, is controllable by selecting appropriate glass composition, and convenient by using common CW lasers.

The synthesis, characterization, photocatalytic evaluation and deactivation behavior of sheet-like nano titania

The sheet-like nano TiO2 particles were prepared by using hydrothermal method, and were characterized by X-ray diffraction(XRD), infrared spectroscopy(IR), and transmission electron microscopy (TEM). It is found that the nanoparticle sizes and crystallinity increase with the increase of hydrothermal temperature from 150 °C to 160 °C, and then to 180 °C. With the increase of particle sizes, the absorption capacities and photocatalytic abilities of as-prepared TiO2 particles for crystal violet become better and better. The nano TiO2 with big particles is more stable than that with small particles, although its initial photocatalytic activity is relatively lower compared with that of the small particle samples.

PLD Preparation of GeS6 Amorphous Film and Investigation on Its Photo-induced Darkening Phenomenon

GeS6 chalcogenide amorphous film was deposited on glass substrate via PLD (pulsed laser deposition) technique. The performance and structure of the film was characterized by XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy), optical transmission spectra, and Raman spectra, etc. The GeS6 amorphous film was irradiated by 532 nm linearly polarized light, and its photo-induced darkening was investigated. The results showed that the GeS6 chalcogenide amorphous film was smooth and compact with uniform thickness and combined with the substrate firmly, and its chemical composition was in consistency with the bulky target. When laser energy was fixed, the transparence of the film declined with the increase of the laser irradiation time. Obvious photo-induced darkening and relaxation phenomenon of the film after laser irradiation were observed in this investigation.

Photo-induced phenomena in GeS4 glasses

GeS4 bulk glasses were prepared by the melt-quench technique and the samples were irradiated by 532-nm linearly polarized light. After the laser treatment, the photo-induced changes of the samples were investigated by UV-1601 spectrophotometer and optical second-order nonlinear tester. The results show that the transmittance of the samples around 532 nm obviously decreases and Bragg reflector forms, which is due to the production of photon-generated carriers. With the increase of laser pulse energy or the extension of irradiation duration, the Bragg reflector increases and gradually tends to be stable. These can be ascribed to the excitationcapture process of the carriers. After irradiation, the relaxation phenomenon results from the release of part of the absorbed energy in the glass matrix. And the fitting equation of the relaxation process is consistent with a conventional Kohlrausch stretched exponential function. The origin of the second harmonic generation (SHG) is because of the dipole reorientation caused by the photo-induced anisotropy in the glass.