Polarized, broadly tunable, 2.3 µm continuous-wave laser operation of Tm³⁺-vanadate crystals

We report for the first time the polarized, broadly tunable, continuous-wave laser operation on the ³H₄ → ³H₅ transition in Tm³⁺-vanadate (Tm:REVO₄, RE = Gd, Y, Lu) crystals. Continuous wavelength tunings with tuning widths of about 200 nm were achieved in π-polarization for both the Tm:GdVO₄ and Tm:YVO₄ crystals. To the best of our knowledge, these tuning widths are broader than most previously reported values for wavelength tunable 2.3 µm Tm lasers. Especially for σ-polarization, all the Tm:REVO₄ lasers provide very smooth wavelength tuning curves around 2.3 µm. This work demonstrates the excellent broad wavelength tunability of the Tm:REVO₄ crystals and their great potential for supporting the generation of ultrashort pulses from mode-locked lasers.