The spectroscopy investigation of ZnWO4:Tm3+ single crystal

► The spectroscopy and refractive index of single crystal ZnWO4:Tm3+ are investigated systematically. ► The Judd-Ofelt parameters are obtained. ► The gain cross sections at ∼2 μm are estimated by reciprocity method (RM). ► The laser operation at ∼2 μm is discussed.