Tm:YAP microchip laser under 1700 nm and 790 nm diode pumping

Abstract

Lasing of Tm³⁺-doped yttrium aluminum perovskite (Tm:YAlO3) microchip laser was investigated. A novel 1.7 μm in-band diode pumping was compared with traditional 0.8 μm pumping of thulium-doped lasers. The sample was b-cut (Pbnm) cylindrical microchip, 5 mm in length and 3 mm in diameter, with its planar surfaces polished and coated: HT for pumping wavelengths (T < 95 % at 1690 nm, T < 95% at 790 nm) and HR R < 99.8 % at 1900–2050 nm at the pumping end and R=97.5–98.5 % at 1900–2050 nm at the output end. The doping concentration was 4 at.% (Tm/Y). The sample was wrapped in an indium foil and held in a water-cooled (11°C) copper holder. For both pumping wavelengths, the sample was longitudinally pumped using a fiber (core diameter 400 μm, NA=0.22) coupled laser diode operating in QCW (25% duty cycle) and CW regime. Under the 1.7 μm diode (delivering up to 30 W at 1680 nm) pumping, obtained slope efficiency (with respect to absorbed power) was 57%. The highest obtained output power amplitude was 14.4 W in QCW and 9.4 W in CW. Under the 0.8 μm diode (delivering up to 20 W at 793 nm) pumping, obtained slope efficiency (with respect to absorbed power) was 58%. The highest obtained output power amplitude was 6.6 W in QCW and 6.9 W in CW. Laser emitted at 1988 nm under all pumping regimes.