Single-shot chirped-pulse spectral interferometry used to measure the femtosecond ionization dynamics of air

A novel interferometry technique is presented by which, in one shot, one ca n measure phase changes with a resolution of tens of femtoseconds while ext ending the measurement over picoseconds or even longer. The method is based on spectral (frequency-domain) interferometry with a pair of linearly chir ped pules as probes. With this technique we obtained single-shot measuremen ts of the rapid phase changes induced by optical field ionization of air. T his allowed us to calculate the time profile of the electron density create d by an intense short laser pulse. (C) 2000 Optical Society of America. OCI S codes: 320.7100, 260.3160, 260.3230, 350.5400.