Qingxi Chen

Optical properties of Yb3+ ions in SiO2?Al2O3?CaF2 glasses

The absorption and emission properties of Yb3+ doped oxy-fluoride-silicate glasses prepared by the melt-quenching method have been investigated. Yb3+ ions in the oxy-fluoride-silicate glasses show large absorption and emission cross-section and the fluorescence lifetimes are longer than 1.3?ms. The minimum pumping intensity, minimum fraction of excited ions, saturation pumping intensity, minimum pulse duration and peak power are also analysed to characterize the samples. The minimum pulse duration and peak power are 79?fs and 0.432?PW?cm?2, which indicates the potential application in high power and ultrashort pulse lasers.

Different refractive index change behavior in borosilicate glasses induced by 1 kHz and 250 kHz femtosecond lasers

We report on different refractive index change (RIC) behavior in borosilicate glasses induced by focused 1 kHz and 250 kHz femtosecond (fs) laser irradiation. The influence of fs laser irradiation condition and annealing temperature on RIC was examined. Absorption, electron spin resonance and Raman spectra, and transmission electron microscope were used to clarify the mechanisms of the RIC. Smaller RIC (up to 10−4) was observed after 1 kHz fs laser irradiation, while larger RIC (up to 10−1) was detected after 250 kHz fs laser irradiation, which were ascribed to the formation of color centers and precipitation of nanocrystals, respectively. The result highlights that the mechanisms of RIC induced by fs laser can be very different depending on the irradiation conditions.

Polarization dependence of the self-organized microgratings induced in SrTiO3 crystal by a single femtosecond laser beam

In this paper, self-organized microgratings are fabricated in SrTiO(3) crystal just by scanning the focus of a tightly-focused linearly-polarized femtosecond laser beam to form a single line. The polarization direction of the laser beam is rotated by a λ/2 waveplate to check the effect of the polarization azimuth on the micrograting morphology. Fourier analyzing of the microscopic images of the microgratings indicates that the polarization plane azimuth of the laser beam does have influence on the microgratings in the aspects of groove orientation and groove spacing. A possible mechanism of polarization dependence is also proposed.