Error bars in intensity and phase measurements of ultrashort laser pulses

Abstract

It is now possible to measure a pulse's intensity and phase versus time. The most commonly used method, frequency-resolved optical gating (FROG), generates the full pulse intensity and phase versus time without making any assumptions about the pulse. As a result, it is potentially accurate, limited only by the accuracy of the measured trace. Just how accurate is a given FROG measurement of a pulse. Some indication of the measured pulse accuracy is available from the FROG error-the rms difference between the measured and retrieved FROG traces. However, a method for determining the error in each of the retrieved intensity and phase points is needed. In other words, we need to be able to place error bars on the intensity and phase at each time (and frequency). We present a simple, robust, and general method for doing this. We apply this method to both theoretical and experimental FROG measurements of pulses and show that it gives reasonable results.