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.

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.

A method to determine the focal length of a thermal lens and pumping laser beam waist in the gain medium in laser-diode-pumped solid-state lasers is presented. This method, using resonator transform circle theory, is both simple and reliable. The measured focal length of the thermal lens is used to calculate the beam waist of pumping laser inside the gain medium. The effect of the thermal lens on the output power is also measured and analyzed.

Er31-doped tellurite glass microspheres were fabricated. The microspheres were made by a spin method. A tapered fiber was used to couple the pump into the microsphere and couple out the laser. L-band microsphere laser is demonstrated. This miniature Er31-doped tellurite glass microsphere laser can be used in photonic microdevices.

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.