Picosecond time-interval measurement and intensity correlations using the two-quantum photoelectric effect

A technique based on the two-quantum photoeffect has been used to measure second-order intensity correlations, pulse shapes from a mode-locked argon ion laser, and time delays in the picosecond domain. Good agreement was obtained between the mode distribution computed from the intensity autocorrelation data and that observed with a scanning Fabry-Perot when the laser was run in the mode-locked condition. Additionally, the contrast ratios observed in both the mode-locked and free-running condition were in good agreement with a theory by Weber and Danielmeyer.