METHODS FOR THE MEASUREMENT OF THE DURATION OF HIGH-HARMONIC PULSES

We present two methods for measuring the duration of ultrashort high-h armonic pulses produced by an intense laser pulse propagating in an at omic gas. Both methods rely on the nonlinearity of ionization of atomi c gases by optical laser pulses. In the first method, the same medium is used for the dual purpose of generating and measuring the high harm onics. The second method uses atomic photoionization in an intense low -frequency laser field to produce the optical analog of a ''streak cam era'' capable of subfemtosecond resolution.