Pulse Characterization By Cascading Nonlinearity Inside A Spectrometer (Canis)

A complete ultrashort pulse diagnostic requires a linear spectrum associated with a nonlinear autocorrelation or interferometric measurement. A new method is presented requiring only a grating spectrometer and two second harmonic crystals. Spectra of fundamental, second harmonic, and two cascaded spectra are used to reconstruct the spectral phase. A few proof-of-concept examples with simple phases are demonstrated using Nelder-Mead algorithm. A differential evolution genetic algorithm is introduced when the pulse has a more complicated shape or phase.