Time-frequency imaging of a single ultrashort light pulse from angularly resolved autocorrelation

A new technique to measure the frequency-resolved temporal image of a single ultrashort light pulse is presented. This technique is based on a single-shot self-diffraction autocorrelator in which the pulse duration is related to the spatial width of a diffracted beam, the pulse spectrum is related to its divergence, and the pulse chirp appears as a curvature of the diffracted-beam wave front. An analysis of wave-front curvature by means of a slit diaphragm and a cylindrical lens results in a time-frequency image of the initial pulse when a spectrometer is not used. This image gives a simple intuitive picture of the chirp and the phase modulation of a pulse.