35-fs diode-pumped mode-locked ytterbium-doped multi-component alkaline-earth fluoride laser

We demonstrate direct generation of sub-40 fs pulses from a diode-pumped mode-locked laser using an ytterbium-yttrium codoped multi-component alkaline-earth fluoride crystal and a semiconductor saturable absorber mirror. The Yb,Y:(Ca,Sr)F₂ laser delivers soliton pulses as short as 35 fs at 1056.7 nm, with an average output power of 182 mW at a repetition rate of ∼65.7 MHz. By increasing the transmittance of the output coupler, the average output power scales to 322 mW at a somewhat longer pulse duration (49 fs) at 1052.5 nm, corresponding to a peak power of 87.9 kW and an optical efficiency of 32.4%. To the best of our knowledge, these are the shortest pulses from a Yb-doped alkaline-earth fluoride crystal.