Measurement of intense u1traviolet femtosecond laser pulses

High energy density physics with extremely intense femtosecond laser pulses is currently emerging as a new field of physics. Amplification of the frequency doubled output of femtosecond dye lasers by means of excimer lasers is widely used for the generation of intense femtosecond pulses in the UV. We have developed a technique based on nonresonant degenerate four-wave mixing (DFWM) to measure the pulse width and pulse structure of UV femtosecond pulses. In short, two equally intense pulses with a variable time delay interact in a thin fused silica sample to produce a DFWM signal proportional to a third-order intensity autocorrelation function.