Zhang Jiahua

Femtosecond Laser Induced Optical Waveguides and Micro-mirrors Inside Glasses

Optical waveguides and micro-mirrors have been successfully induced inside fused silica glass and k9 glass, respectively, by focusing a 800 nm femtosecond (fs) pulsed laser with a repetition rate of 1 kHz. The change of refractive index was determined to be 0.001-0.008 in the fused silica glass and 0.006 in the k9 glass. The refractive index change is dependent on both the dose of irradiation and the power density of the fs pulsed laser. Photoluminescence was observed in the irradiated region, and was attributed to the defects induced by fs laser irradiation. We discuss the relationship between the optical property and the luminescent property of the irradiated region.

Investigation of the Insulator-Metal Transition Mechanism in trans-Polyacetylene

By using the Hamiltonian included in the static Su-Schrieffer-Heeger model and the Coulomb potential of solitons and ions, we investigated the insulator-metal transition mechanism in Na-doped trans-polyacetylene and gave the dependence of the Pauli susceptibility for 8.33% Na doping on the various widths and arrangements of the solitons.

The Mode Matching of Hybrid Trap by Frequency Calibration

We demonstrate a method to precisely calibrate the relative position between an optical dipole trap and a magnetic quadrupole potential in making a Bose-Einstein condensate via the hybrid trap. We measure the displacement by the dipole oscillation in the gravity direction, where the oscillation frequency can be adjusted through an additional bias magnetic field. One frequency corresponds to the case of the mode matching while two frequencies are not, and the great consistency between theoretical simulation and experimental results indicates its usefulness.