Experimental study on measuring pulse duration in the far field for high-energy petawatt lasers.

We study the feasibility of measuring pulse duration in the far field in high-energy petawatt lasers using single-shot autocorrelation. This single-shot autocorrelation technique makes use of parametric upconversion in media with randomly oriented ferroelectric domains, which supports transverse second-harmonic generation with two counter-propagating fundamental beams. We show that this technique possesses a large time window, capable of measuring pulses with temporal duration ranging from a sub-picosecond to tens of picoseconds. We test the performance of this technique in the presence of multipulse structures, intensity modulations in the near field, and spatial-temporal coupling in fundamental beams. We also investigate the influence of beam pointing discrepancy on the measurement. Our study can serve as a preliminary experiment for robustly characterizing pulse duration in high-energy petawatt lasers.