由测量的Tm: YVO4晶体的吸收光谱，考虑到单轴晶体在各个方向上的吸收不同和折射率随波长的变化，根据Judd-Ofelt理论计算了Tm3-在YVO4中的强度参数!各个能级的振子强度、自发辐射几率、荧光分支比、积分发射截面等参数。强度参数为Ω2=1.941×10-20(cm2), Ω4=0.1568×10-20(cm2), Ω6=0.3963×10-20(cm2),计算结果表明1D2→3F4的跃迁几率远大于1D2向其他各个能级的跃迁几率。

Frequency upconversion into green and red luminescence in erbium-ytterbium-codoped phosphate glass pumped with a 970 nm diode laser is presented. The red upconversion emission results from a two-photon excitation process. The green emission results from a two- or three-photon excitation process with the two-photon process dominating at low pumping power. Based on measurement of the excitation and emission spectra, a model of the three-photon excitation process has been developed. This model provides a good basis for explaining the effect of the three-photon process on the saturation of 1.54 mm laser power of Er, Yb-codoped phosphate glass laser.

Er3+,Tm3+-codoped NaY(WO4)2 crystal was prepared by using Czochralski (CZ) pulling method. Absorption spectra, emission spectra and excitation spectra of this crystal were measured at room temperature. Such optical parameters as intensity parameters, spontaneous emission probabilities, branch ratios and lifetimes are calculated from absorption spectra with Judd-Ofelt theory. Transition processes of the energy levels of Er3+, Tm3+ are analyzed in details and the cross-relaxations: 1G4(Tm3+) + 4I15/2(Er3+)→3F2(Tm3+) + 4I13/2(Er3+), 1G4(Tm3+) + 4I15/2(Er3+)→3F4(Tm3+) + 4F9/2(Er3+) and 3H4(Tm3+) + 4I9/2(Er3+)→3F4(Tm3+) + 4S3/2(Er3+) or 2H11/2 between the two ions are put forward. Through the experiments, we have found that, in this crystal, Tm3+ strengthens luminescence of Er3+ in the green and red regions evidently. The above energy transfer processes provide potential applications of Tm3+ in Er3+-doped laser materials.

We report on the temperature dependence of L-band laser emission of fiber-taper-coupled Er31-doped tellurite glass microsphere. The microsphere laser emission threshold increased and the emitted laser wavelength shifted with temperature. The experimental results are explained with a quasi-four-level model, showing that a significant reduction of laser threshold can be achieved at lower temperatures and higher Q values of this microsphere laser.

Rate-equation analysis and experiments on a pulsed dual-wavelength Ti:sapphire laser are reported in the paper. A four-energy-level system with two lower-energy levels is put forward and numerical calculations are given. A simple optical setup with two sub-resonators is constructed, which yields a total energy from dual-wavelength lasers up to 41.8mJ. The largest tunable range is over 110nm. Laser characteristics of dual-wavelength pulses are observed. Experimental results are in accord with rate-equation-theory results.