Interferometric studies of mode-locked Nd3+: Glass lasers

A general technique for measuring the electric-field vector of the ultrashort pulses from mode-locked laser systems is described. The technique is applied to perhaps the most difficult laser to analyze, the dye mode-locked Nd³⁺:glass laser whose pulses change rapidly in bandwidth and amplitude, are chirped, and can occur in quite short pulse trains. The results of these measurements indicate a rather rapid change in the phases between modes, and a plot of the phase change as a function of mode frequency has been obtained.