Room-temperature CW laser operation at ∼1.55 μm (eye-safe range) of Yb:Er and Yb:Er:Ce:Ca/sub 2/Al/sub 2/SiO/sub 7/ crystals

Abstract

Room-temperature CW laser operation at 1.55 /spl mu/m of Yb:Er:Ca/sub 2/Al/sub 2/SiO/sub 7/ (CAS) single crystal pumped at 940 nm and 975 nm has been achieved for the first time. Introduction of a third doping ion, Ce/sup 3+/, decreases the Er/sup 3+4/I/sub 11/2/ excited-state lifetime and improves the laser properties. For Yb:Er:Ce:CAS single crystal, a maximum of 20 mW output power is produced for 285 mW absorbed power. With this material, a low threshold of 20 mW and a relatively high slope efficiency of /spl sim/5.5% are obtained. Preliminary results indicate possible improvement in the near future. Experimental threshold values and laser properties of CAS crystals with various compositions are in good agreement with calculations, performed using the rate-equations modeling. Comparison with a Yb:Er:phosphate glass laser is also presented.