The effect of pulse to pulse variation on ultrashort pulsewidth measurements

An alternate interpretation is presented for the exponential shapes of the second harmonic autocorrelation functions obtained from synchronously pumped mode locked dye laser systems. The shape is reinterpreted as being due to a weighted average of pulses of varying widths and smoothly varying pulse shapes in time. Such pulse width measurements in the past have averaged over a large number of pulses. Several pulse shapes and pulse width distributions are examined all leading to exponential shaped autocorrelation functions. This interpretation implies that the currently determined pulsewidths are shorter, possibly many times shorter than the actual average pulsewidths. A method for selectively descriminating the shortest pulses from the train to increase the time resolution of current laser systems is presented.