Effects of P co-doping on X-ray/450 nm LD induced photodarkening in Dy3+ doped silica glass and fiber laser

Abstract

Effects of P-codoping on X-ray/450 nm LD induced photodarkening in Dy3+ doped silica glass and fiber were investigated to develop a visible fiber laser. P and Dy concentrations in Dy-P-doped silica glass were optimized to reduce Rayleigh scattering. It was found in optimized glass that X-ray-induced photodarkening can be well suppressed by P co-doping. 450 nm LD pumped laser oscillation was firstly observed in the fiber using optimized glass. The slope efficiency is 4.2% which is lower than those in Dy–Al-and Dy–Al–Ge-doped fibers previously reported. Contrary to the results of X-ray-induced PD, 450 nm LD-induced photodarkening easily occurred.