Influence of Stark splitting levels on the lasing performance of Yb3+ in phosphate and fluorophosphate glasses

Lasing properties have been investigated for Yb3+ doped glasses with similar emission cross sections (sigma(emi)) and lifetime while possessing different Stark levels. Narrow Stark splitting of Yb3+-phosphate glass is responsible for severe heat generation, narrow emission band and much smaller semi at lasing wavelength, making Yb3+-phosphate glass unsuccessful to achieve laser output, whereas 1.166W cw laser was obtained in Yb3+-fluorophosphate (FP) glass with broader Stark splitting. Analysis on laser system levels reveals that under room temperature, Yb3+ laser is quasi-3.13-level in phosphate glass and quasi-3.36-level in FP glass. These demonstrations suggest that unless the Stark splitting is enlarged, conventional Yb3+-phosphate glass is not a good gain medium for bulk Yb3+-laser. (C) 2015 Optical Society of America