Angular chirp and tilted light pulses in CPA lasers

Abstract.

We investigate analytically and experimentally various aspects of the angular chirp of ultrashort laser pulses. This type of chirp is easily produced by slight misalignment of standard pulse stretcher and/or compressor setups. Angular chirp leads to tilted pulse fronts in the near field and to a strong reduction of intensity in the focus. The effect is rather difficult to observe with standard diagnostic techniques. We present a method that is based on interferometric field autocorrelation and allows us to measure the angular chirp reliably. Suggestions on how to avoid this effect are outlined as well.