Abstract

We report and demonstrate what is to our knowledge the first measurement of the intensity and phase of a single femtosecond UV pulse. The technique, which we call frequency resolved optical gating (FROG), is inexpensive, easy to implement, and provides an output that graphically displays the instantaneous frequency vs. time of the pulse. It uses the well-known polarization-spectroscopy optical-gate arrangement with an instantaneously responding χ⁽³⁾ sample medium such as quartz. Here, however, the pulse gates itself. The signal spectrum is then measured as a function of delay between the two input pulses. Because the gate is shorter than the input pulse, it reveals, for a given delay, the frequency of a particular temporal component of the ultrashort pulse. For reasonably well-behaved pulses, the output plot of intensity vs. frequency and delay graphically displays the pulse instantaneous frequency vs. time.

© 1992 Optical Society of America