High−power mode−locked TEA CO2 laser using an unstable resonator

A passively mode−locked TEA CO2 laser has been operated with an unstable resonator, and mode−locked trains with peak powers ≳150 MW, together with near diffraction−limited beams, have been obtained. Single axial mode operation at a power level of 14 MW has also been achieved. These results represent a significant improvement over similarly dimensioned systems using stable resonators.