Excited-state absorption and upconversion pumping of Tm3+-doped potassium lutetium double tungstate

Identifier:  imarina:9299802

Handle: https://hdl.handle.net/20.500.11797/imarina9299802

Authors:  Tyazhev, A; Loiko, P; Guillemot, L; Kouta, A; Sole, RM; Mateos, X; Aguilo, M; Diaz, F; Dupont, H; Georges, P; Druon, F; Braud, A; Camy, P; Hideur, A

Abstract:
We report on a bulk thulium laser operating on the 3H4 → 3H5 transition with pure upconversion pumping at 1064 nm by an ytterbium fiber laser (addressing the 3F4 → 3F2,3 excited-state absorption (ESA) transition of Tm3+ ions) generating 433 mW at 2291 nm with a slope efficiency of 7.4% / 33.2% vs. the incident / absorbed pump power, respectively, and linear laser polarization representing the highest output power ever extracted from any bulk 2.3 µm thulium laser with upconversion pumping. As a gain material, a Tm3+-doped potassium lutetium double tungstate crystal is employed. The polarized ESA spectra of this material in the near-infrared are measured by the pump-probe method. The possible benefits of dual-wavelength pumping at 0.79 and 1.06 µm are also explored, indicating a positive effect of co-pumping at 0.79 µm on reducing the threshold pump power for upconversion pumping.