Highly sensitive direct femtosecond pulse characterization using electro-optic spectral shearing interferometry

We report the first experimental demonstration of spectral shearing interferometry using a electrooptic temporal phase modulator to generate the spectral shear. This approach achieves far better sensitivity in comparison with the nonlinear optical pulse characterization techniques, including other version of spectral shearing interferometry. Linear temporal phase modulation is conceptually simple and is implemented easily with telecommunication components. The technique is versatile and a wide range of pulse duration can be measured with minimal changes in the setup. We experimentally demonstrate the accurate characterization of a 156 MHz train of 1540-nm pulses with durations from 750 fs to more than 30 ps after various amounts of chirping, at average powers below 1 mW.