SITE-SELECTION SPECTROSCOPY, ENERGY-TRANSFER, AND LASER-EMISSION IN ND-3+-DOPED BA2MGGE2O7

A detailed spectroscopic and pump wavelength dependent laser study has been performed on Nd3+ ions in Ba2MgGe2O7. Site-selection spectroscopy experiments reveal fifteen distinct crystal field sites for the Nd3+ ions. At room temperature, excitation of ions in any one of these sites is followed by efficient, thermally activated energy transfer to ions in a site having a laser emission transition at 1054 nm. Laser-pumped laser experiments were performed to determine the pumping threshold and slope efficiency of laser action in this material for different monochromatic pump wavelengths. The measured slope efficiencies were found to be pump wavelength dependent and ranged from 6% to 22%. Excited-state absorption of pump photons was shown to be responsible for this variation in the slope efficiency.