Growth by liquid phase epitaxy and low threshold laser oscillation at 2.012µm of a Tm:YAG waveguide laser

We report the growth by liquid phase epitaxy and laser operation at 2.012 micrometers of Tm:YAG planar waveguides with various concentrations (4 to 10 at %), lengths (3,4 mm) and active layer thicknesses (8 to 30 micrometers ). The pumping source was 1 W GaAlAs SDL diode emitting at 785 nm and the cavity consisted of 2 plane mirrors butted to the waveguide endfaces. Initial results have been obtained with a 6% doped, 4 mm long and 14.6 micrometers thick, Tm:YAG epilayer: Thresholds occurred at respectively 60 mW and 300 mW of incident power (48 mW and 136 mW of absorbed power taking in account pump feedback by the output couplers) for output mirrors transmissions of 2% and 12% respectively. Slope efficiencies of 32% and 48% with respect to absorbed power have been achieved with these output transmissions. With Ti:sapphire pumping an using 1.8% output coupling, laser threshold as low as approximately equals 10 mW and slop efficiencies of approximately equals 30% have been obtained in a range of different Tm:YAG waveguides. This performance is comparable to the best results published until now for bulk crystals