Shortening of pulses emitted from a mode-locked ruby laser by deliberate broadening of the emission spectrum and reduction of the relaxation time of a saturable filter

The emission spectrum of a mode-locked ruby laser was broadened to 5 cm^–1 by a plane-parallel glass plate. The relaxation time of a saturable filter, which also influenced the pulse duration, was minimized by the use of solutions with a maximum concentration of cryptocyanine. The duration of the pulses emitted under these conditions was measured with an ultrafast saturable-filter optical switch and it was found that the pulse duration was 15 psec, which was 1.5 times shorter than in the case when a dilute cyptocyanine solution was used.