Laser operation of cleaved single-crystal plates and films of Tm:KY(MoO₄)₂

We report on the crystal growth, spectroscopy and first laser operation of a novel double molybdate compound - Tm:KY(MoO₄)₂. This orthorhombic (sp. gr. Pbna) crystal exhibits strong anisotropy of the spectroscopic properties due to its layered structure. The maximum stimulated emission cross-section for the ³F₄ → ³H₆ transition is 2.70×10^-20 cm² at 1856nm with a bandwidth of >110 nm (for E || b). The lifetime of the ³F₄ state is 2.29 ms. Crystalline films and plates (thickness down to 70 µm) of high optical quality are obtained by mechanical cleavage along the (100) plane. Continuous-wave diode-pumped laser operation is achieved in such thin films and plates yielding a maximum output power of 0.88 W at ∼1.9 µm with a slope efficiency of 65.8% and a linearly polarized laser output. Vibronic lasing is demonstrated at ∼2.06 µm. Tm:KY(MoO₄)₂ is promising for microchip and thin-disk lasers.