DIRECT DEMONSTRATION OF PICOSECOND-PULSE FREQUENCY SWEEP

Abstract

A direct measurement using time-resolved spectroscopy with response times in the picosecond regime shows that wave groups of different frequencies within an ultrashort pulse generated by a Nd-glass mode-locked laser arrive at a given point at different times. A curve depicting wavelength versus arrival time for a typical pulse is constructed. The frequency sweep is nonlinear and positive across the most intense portion of the spectrum.