Kerr-lens mode-locked Tm-doped sesquioxide ceramic laser

Kerr-lens mode-locked solid-state laser operation at ∼2µm is investigated. Using a Tm³⁺-doped (Lu,Sc)₂O₃ "mixed" sesquioxide ceramic as a gain medium, pulses as short as 58 fs are generated at ∼2081nm via soft-aperture Kerr-lens mode locking. The average output power amounts to 220 mW at a pulse repetition rate of 84.8 MHz. The emitted spectrum at the long-wavelength wing extends to >2.2µm which is attributed to vibronic transitions of the Tm³⁺ ions. The latter is found to be essential for generating pulses with durations in the 50 fs range.