Comparison of Laser Performance for Diode-Pumped Tm:YLF of Various Doping Concentrations

Abstract

Single-end-pumped laser performance of 2, 4, and 6at.% Tm-doped YLF rods is reported. For the pumping configuration employed, crystal fracture was observed to occur for a thermal load per unit absorption length of ~13W/cm. The 2at.% Tm-doped crystal was found to have a quantum yield of ~90% of that of 4at.% Tm. However, due to a lower thermal loading density, the maximum possible incident pump power is predicted to be >60% higher, hence offering a greater output power per rod for the lower doping concentration. Power scaling considerations are discussed with reference to crossrelaxation, upconversion, and thermal loading of the host crystal.

Thermal analysis of double-end-pumped Tm:YLF laser

“…where η h is the thermal conversion coefficient, which is the proportion that crystal absorption power is converted into a thermal load, and it is mainly decided by the crystal doping concentration; In [11], when the crystal doping concentration is lower than 4 at.%, the thermal load produced by the ETU (energy transfer upconversion) is so small that we can ignore it, and then η h = 1 − Q y λ p /λ l , λ p is pump wavelength, λ l is laser wavelength, Q y is quantum efficiency, which is also decided by the crystal doping concentration, whose value is shown in table 1.…”

“…T 0 (11) The variation in OPD across the block is equivalent to a lens of focal length satisfying [12,13]…”