Accurate characterization of complex pulses by delay-controlled fringe-free interferometry of spectral high-resolution technique

We discuss the disadvantage in conventional Spectral Phase Interferometry for Direct Electric-field Reconstruction (SPIDER) technology in complex femtosecond pulse measurement. An improved version of conventional technology named DC-FISH is presented, where single replica of the unknown pulse upconverts synchronously with two frequency-shifted narrow-banded long pulses. The spectral phase of the unknown pulse can be directly calculated from the fringe-free spectra with the introduction of a suitable small delay between the upconverted pulses. The numerical simulation results are achieved to identify a higher efficiency and lower requirements on measurement in novel approach.