Diode-pumped cw and fs laser based on Yb:CaF2

Results of diode-pumped cw and fs laser operation of an Yb3+:CaF2 single crystal are reported. With a 5-at.-% Yb3+-doped sample we obtained 5.8 W output power at 1053 nm, for 15 W of incident pump power at 980 nm. In passively mode-locked diode-pumped regime, using a Brewster-cut, 5-at.-% Yb3+-doped sample and prisms for dispersion compensation, the oscillator provided pulses as short as 150 fs, with 880 mW of average power and up to 1.4 W average output power, with pulse duration of 220 fs, centred at 1049 ran. The laser wavelength could be tuned from 1018 nm to 1072 nm in cw regime and from 1040 nm to 1053 nm in mode-locked regime. Using chirped mirrors for dispersion compensation, we obtained up to 1.74 W of average power, with pulse duration of 230 fs. For all these reasons, Yb:CaF2 crystal is showing the great potential as active medium for high average power femtosecond oscillators and as amplifier medium for femtosecond pulses.