Ultrashort pulse chirp measurement via transverse second-harmonic generation in random nonlinear crystals

The second order transverse autocorrelation technique, using a nonlinear crystal with a random-size and distribution of antiparallel nonlinear domains, has been recently proved to be an effective method for ultrashort pulse characterization in the range of 200 fs, allowing the pulse duration and initial chirp measurement [1]. In this work we show that this method can be extended to the measurement of shorter pulses down to 30 fs. This technique permits an in-situ analysis of the pulse evolution and provides a simple way to measure the pulse chirp acquired during propagation in the optical system.