Spectroscopic and second harmonic generation properties of a new crystal: Yb-doped RbTiOPO4

Abstract RbTiOPO4 single crystals doped with a concentration of 1.96 × 1020 ions cm−3 of Yb3+ have been grown. These crystals exhibit a large splitting of the 2F5/2 sublevels of Yb3+ of about 70 nm, which is one of the largest crystal fields ever known for Yb-doped crystals. The larger compensation is ensured by a Nb-co-doping. As expected from the large splitting, a broadband fluorescence was observed around 1 μm, which is interesting for tunability and subpicosecond-pulse generation applications in the visible and in the infrared domains. The excited-state lifetime has a quite long value of 2.2 ms, which is favourable to get a high inversion of population under CW pumping. Measurements of second harmonic generation have shown a correlation between the fundamental wavelength of angular non-critical phase-matching and the concentration of Nb and Yb. The conversion efficiency is of the order of that of RTP.