Femtosecond-pulse laser chirp compensated by cavity-mirror dispersion

The duration of pulses generated from a simple colliding-pulse mode-locked cw dye laser is measured as a function of cavity-mirror dispersion. The optimum amount of mirror dispersion of ø (omega) congruent with + 1.8 x 10(-28) sec(2) and a suitable mirror coating for upchirp compensation are identified. The adjustment of mirror dispersion only, without additional dispersive elements, generates continuous trains of pulses as short as 50 fsec.