Abstract

Recently, we introduced a new high-spectral-resolution and experimentally simple spectral-interferometry method for measuring the intensity and phase of potentially complicated ultrashort pulses, which we call SEA TADPOLE[1], We showed that SEA TADPOLE can exhibit spectral super-resolution. Other notable properties of SEA TADPOLE are that its entrance is an optical fiber (see Fig. 1) with a core size of only a few pm (or less) (the dispersion of this fiber cancels out of the measurement) and SEA TADPOLE is very sensitive, requiring only a few thousand photons for a measurement. For these reasons, SEA TADPOLE can measure a tiny region of a collimated, diverging, or converging beam, and it can measure a tightly focused beam. Additionally, the entrance fiber can be scanned along the unknown beam in all three directions of space so that the intensity and phase as a function of transverse and/or longitudinal position can also be measured. While techniques for characterizing the spatio-temporal field have been developed, they all require a collimated input beam and therefore cannot make the measurement at a focus[2], and the only methods available for measuring pulses at the focus simply measure the pulse vs. time, averaging over spatial variations. Thus, we believe that the technique presented here is the first technique ever developed for measuring the intensity and phase vs. space and time at and near a focus.

© 2007 IEEE