Dual-wavelength laser of heavily Yb3+-doped NaGd(WO4)2 crystals

NaGd(WO4)2 crystals with 10 at%, 15 at%, 20 at% and 30 at% Yb3+-doped concentrations have been grown by the Czochralski method. The spectroscopic properties of Yb3+: NaGd(WO4)2 with different Yb3+ concentrations have been studied detailed in this paper. We found that the emission cross sections and the lifetime increased with the increase of Yb3+ concentration. However, by comparing their laser output power, 10 at% Yb3+: NaGd(WO4) is more appropriate for laser operation. Finally, the orthogonally polarized dual-wavelength laser operation of 10% Yb3+: NaGd(WO4)2 crystal was realized. The maximum output power of the dual-wavelength laser is 1.86 W with T = 3.0%, which is calculated with the 1000 Hz, 0.3 duty ratio pulses. The dual-polarization and dual-wavelength laser oscillated at 1046 nm in σ polarization and 1053 nm in π polarization. For T = 2, 5, 7%, the gaps of dual-wavelength are all about 5 nm.