28.02 W LD side-pumped CW laser operated at 2.8†µm in YSGG/Er:YSGG/YSGG crystal.

We demonstrated a 978 nm laser diode (LD) side-pumped YSGG/Er:YSGG/YSGG composite crystal with a size of Ф 3 mm × 65 mm and continuous-wave (CW) mode. By optimizing resonator length and output mirror transmittance, a maximum output power of 28.02 W is generated, corresponding to slope efficiency of 17.55% and optical-optical efficiency of 12.29%, respectively. The thermal focal lengths are obtained by resonator stability condition. The laser wavelength is centered near 2.8 µm. Moreover, the beam quality factors M x2/M y2 are fitted to be 8.14 and 7.35, respectively. The above results indicate that a high-performance 2.8 µm CW laser can be achieved by LD side-pumped YSGG/Er:YSGG/YSGG composite crystal with excellent heat dissipation ability, which promotes effectively the development and applications of the mid-infrared solid-state lasers.

Polarization switching in a mid-infrared Er:YAlO3 laser.

We report on a polarization-resolved study of mid-infrared emission properties of Er3+-doped orthorhombic yttrium aluminum perovskite YAlO3 single crystal. For the 4I11/2 → 4I13/2 Er3+ transition, the stimulated emission cross section is 0.20 × 10-20 cm2 at 2919 nm for light polarization E ‖ c. Pumped by an Yb-fiber laser at 976 nm, the 10 at.% Er:YAlO3 laser delivered 1.36 W at 2919 nm with a slope efficiency of 31.4%, very close to the Stokes limit, a laser threshold as low as 33 mW and a linear polarization. Pump-induced polarization switching between E || b and E || c eigen states was observed and explained by excited-state absorption from the terminal laser level.