Junfang Liu

Near-infrared broadband luminescence in Bi2O3-GeO2 binary glass system

Near-infrared broadband luminescence from 1100 to 1600 nm was observed in Bi2O3-GeO2 binary glasses. The strongest emission can be observed with 30 mol % Bi2O3 when pumped at 808 nm. The lifetimes of all samples are longer than 200 μs. The glass network was studied by Raman spectra and Bi+ ions are proposed as the infrared luminescence centers in this glass system. Thermal treatment in air results in partly oxidation of Bi+ to Bi2+.

Continuous-wave and mode-locked operation of a diode-pumped Nd,La:CaF 2 laser

A diode-pumped passively mode-locked Nd,La:CaF2 laser has been investigated by using a semiconductor saturable absorber mirror (SESAM) for the first time. With Nd,La:CaF2 disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration of 11 ps and repetition rate of 87.5 MHz at the central wavelength of 1065.8 nm. The maximum average output power was 110 mW corresponding to pulse energy of 1.26 nJ and peak power of 115 W, respectively. Additionally, continuous wave (CW) laser output performance of Nd,La:CaF2 was investigated, and the maximum average output power was as high as 488 mW.

Crystal growth, polarized spectroscopy and Judd-Ofelt analysis of Tb:YAlO 3

Tb3+-doped YAlO3 (YAP) single crystal was grown by Czochralski (Cz) method. Based on the polarized absorption spectra, the spectroscopic parameters were calculated to be Ω2=3.49×10-20cm2, Ω4=5.87×10-20cm2 and Ω6=2.55×10-20cm2, and then the spontaneous transition rate, fluorescent branching ratio and radiative lifetime of 5D4 multiplet were obtained. The yellow emission cross sections of 5D4→7F4 transition were calculated to be 1.72×10-22cm2, 2.73×10-22cm2 and 2.65×10-22cm2 for a, b and c polarization, respectively. The fluorescence lifetime of the 5D4 multiplet was fitted to be 1.72ms. All the data indicate that Tb:YAP crystal is a promising candidate for yellow laser operation.

Diode-pumped laser performance of Tm:Sc2SiO5 crystal at 1971 nm

The 4-at.% Tm:Sc2SiO5 (Tm:SSO) crystal is successfully obtained by the Czochralski method. The optical properties and thermal conductivity of the crystal are investigated. The broad continuous wave (CW) laser output of (100)-cut Tm:SSO with the dimensions of 3 mm× 3 mm× 3 mm under laser diode (LD)-pumping is realized. The full width at half maximum (FWHM) of the laser emitting reaches up to 21 nm. The laser threshold of Tm:SSO is measured to be 0.43 W. Efficient diode-pumped CW laser performance of Tm:SSO is demonstrated with a slope efficiency of 25.9% and maximum output power of 934 mW.