22-MW BLUE OUTPUT POWER FROM A PR3+ FLUORIDE FIBER UP-CONVERSION LASER

From a Pr3+-doped fluoride fibre upconversion laser with a fibre length of 78 cm and an output coupling of 30%, 22 mW blue (492 nm) output power, with an overall conversion efficiency of 7.5%, has been achieved. The total pump power threshold of about 80 mW was less than the previous lowest threshold. Both the output power and the conversion efficiency are, we believe, the best reported to date for a blue Pr3+-doped fibre laser. These results demonstrated the potential for a diode-pumped solid state blue laser.