New autocorrelation technique for the IR FEL optical pulsewidth measurements

In this paper we will present a new autocorrelation method for the IR FEL optical pulsewidth measurements at Vanderbilt University. This method is based on absorption of radiation due to two-photon absorption (TPA) of Ge, InAs, and Te semiconductors. The theory of this method, along with the experimental setup and autocorrelation measurements utilized are presented. Also results of this method are compared with the standard method of second harmonic generation (SHG).