Optical spectroscopy and efficient continuous-wave operation near 2 μm for a Tm, Ho:KYW laser crystal

The growth, spectroscopy and lasing performance of a novel Tm, Ho:KY(WO4)2 crystal are reported. The peak emission cross-section of the Ho3+ 5I7→5I8 transition and lifetime of the 5I7 excited state were determined to be 4.8×10−20 cm2 and 1.8 ms, respectively, in a spectral range at around 2060 nm. Using a Ti:sapphire laser as a pump source at 802 nm, a maximum slope efficiency of up to 44% has been achieved with a corresponding output power of 460 mW at 2056 nm during continuous-wave operation of a Tm, Ho:KY(WO4)2 laser at room temperature. A tuning range of 1890–2080 nm has been demonstrated.