Investigation Of Pumping Dynamics In Rare Earth Doped Solid State Laser Materials

The pumping dynamics of rare earth doped solid state laser materials are discussed here with an emphasis on the effects occurring in laser-pumped laser systems. A tunable alexandrite laser is used as the pump source for Nd3+-doped laser materials. It is found that the slope efficiency of the Nd laser operation depends strongly on the wavelength of the pump laser. For pump wavelengths resulting in low slope efficiencies strong fluorescence emission is observed from the sample in the blue-green spectral region. This is attributed to the excited state absorption of pump photons which occurs during radiationless relaxation from the pump band to the metastable state. It is shown to be an important loss mechanism in laser-pumped laser systems for specific pump wavelengths.