Diode-end-pumped room temperature Tm, Ho:YLF lasers

Room- temperature operation of continuous- wave and Q- switched Tm, Ho: YLF lasers are reported. A 3W CW laser- diode in an end- pumped geometry is used to generate 393mW of 2 mu m laser output, representing a 14% optical to optical efficiency. In order to achieve single frequency operation, two intra- cavity solid etalons are used. Single frequency output power of 113mW is obtained, and the threshold power is only 250mW. The single frequency laser can be used as a seed laser for either a larger oscillator or an amplifier. In the acousto- optic Q- switched operation, laser pulses with the energy of 45 mu J and 142ns FWHM width have been achieved for the pump power of 1.7W. We give the analytical formulas of the threshold pump power and slope efficiency to theoretically analyze the results obtained in the experiments, in which the energy transfer up-conversion and ground state re- absorption are taken into account. (C) 2005 Optical Society of America.