Superluminal propagation of an optical pulse in a Doppler broadened three-state, single channel active Raman gain medium

摘要

Using a single channel active Raman gain medium we show a $(220\pm 20)$nsadvance time for an optical pulse of $\tau_{FWHM}=15.4 \mu$s propagatingthrough a 10 cm medium, a lead time that is comparable to what was reportedpreviously. In addition, we have verified experimentally all the featuresassociated with this single channel Raman gain system. Our results show thatthe reported gain-assisted superluminal propagation should not be attributed tothe interference between the two frequencies of the pump field.