White-light gated holography in Li NbO/sub 3/

CWE6 Fig. 1 Upper: Schematic (top curve) showing a strong ultrashort pulse after propagating through an absorbing gas and hence with a free-induction-decay tail, containing the gas absorption information. Ifthis waveform is gated, as shown in the in the second curve, then the waveform shown as the third curve results. Lower: Absorption spectrum of a weak narrowband absorbtion in the spectrum of an ultrashort laser pulse (thin curve). The narrow absorption dip corresponds to a slow free-induction decay following the ultrashort pulse. Gating out most of the ultrashort pulse in time reduces the broad background relative to the narrowband absorber and improves the depth of the dip relative to the background and hence the sensitivity (thick curve).