Temporal interferometric measurement of femtosecond spectral phase

Fourier spectral analysis of temporal interference resulting from beats between a reference optical frequency and a number of spectral components of a femtosecond optical pulse yields the spectral phase directly without the need for iterative calculations. A periodic multiple-slit mask placed in the Fourier plane of a femtosecond pulse shaper selects an ensemble of frequency components for measurement by cross correlation. An additional, out-of-period slit selects the reference frequency so that none of the desired beat tones overlaps redundant tones. We measure positive and negative cubic phase distortion introduced when the pulse shaper lens is tilted and the phase discontinuity of a 0-pi pulse (odd pulse) with a 13-slit mask. Finally, we demonstrate measurement of the spectral phase associated with true time delays with 17 slits.