Highly efficient dual-wavelength laser operation of cryo-cooled resonantly (in-band) pumped Ho3+:YVO4 laser

We have demonstrated a CW, multiwatt, dual-wavelength cryogenically cooled, resonantly (in-band) pumped Ho(3+):YVO(4) laser with nearly quantum-defect-limited performance. The Ho(3+)(2%):YVO(4) gain element, which was maintained at ~80 K and pumped by a Tm-fiber laser at 1966 nm, emitted at wavelengths of either 2053 or 2068 nm, or both at the same time, depending on the outcoupling loss and the pump power. We have achieved laser operation with a maximum slope efficiency of ~92%. This is, to the best of our knowledge, the highest slope efficiency ever demonstrated for any Ho(3+)-doped laser.