Spectral shearing interferometry with spatially chirped replicas for measuring ultrashort pulses

A new spectral shearing interferometry technique for ultrashort pulse characterization is demonstrated. The method makes use of a spectral shear that varies across the test pulse beam profile to generate a two-dimensional interferogram that allows simultaneous reference phase measurement and pulse-field reconstruction from a single data set. The method uses a new configuration for upconversion of a single (non-spatially chirped) test pulse with two spatially chirped ancillary pulses in a medium with a highly asymmetric phase matching function. This technique is particularly suited for spectral regions where second harmonic is much easier detectable that the fundamental wavelength, such as telecom band around 1.5 μm, since all the data are available from the measurement at the upconverted wavelength. The high degree of redundancy in the two-dimensional interferogram provides a built-in check of the consistency of the reconstruction.