1-W average power levels and tunability from a diode-pumped 2.94-microm Er:YAG oscillator

A tunable Er:YAG laser, side pumped by a quasi-cw InGaAs diode array, generates > 500 mW of power at 2.936 microm. The cavity is a 4-cm plano-concave resonator that uses total internal reflection on the pump face of the Er:YAG crystal to couple the diode emission into the resonating modes of the oscillator. Tuning is accomplished by angle tuning a 300-microm-thick YAG étalon. The tuning range is 2.933-2.939 microm. Thermal lensing limits the duty factor to 4% or 8%, depending on the Er:YAG crystal thickness (2 or 1 mm). A 2.5-cm-long resonator operates at an 11% duty factor and generates 1.3 W of average power.