Experimental observation of optical precursors in optically pumped crystals.

We experimentally observed optical precursors in optically pumped crystals using polarization-based interference. By switching the user-programmable médium among the fast light, slow light, and no-dispersion regimes, we observed an unchanged polarization state for the wave fronts. The robust polarization-encoded information carried by wave fronts suggests that precursors are the preferred carriers for both quantum and classical information in communication networks. [ABSTRACT FROM AUTHOR]