Femtosecond Time-Space Holograms: Diffraction on the Edge of Time

Time- and space domain (TSD) holography [1-3] can be viewed upon as a more general case of conventional holographic process, in which the recording media re members, in addition to the spatial picture, also the spectral intensity of the illuminating light. The resolution of TSD-holograms in time is Fourier-related to the spectral properties of the recording media. The longest time interval that can be recorded is given by the inverse value of the homogeneous width of the zero-phonon line and the shortest time is given by the inverse value of the width of the inhomogeneous distribution in the frequency dimension. By using photochemical spectral hole-burning in organic dye-polymer systems with very broad inhomogeneous bands TSD-holograms of full scenes of ultrafast events with subpicosecond time resolution have been recorded [4, 5].