Direct Visualization of Collective Wavepacket Dynamics

Direct spatiotemporal imaging of optic phonon−polariton wavepackets in polar crystals is demonstrated experimentally and described theoretically. Spatiotemporal imaging permits monitoring of wavepackets as they move through host samples at lightlike speeds. Different imaging methods may be used optimally for wavepackets with different spatial distributions, including spatially periodic or nonperiodic wavepackets. Spatiotemporal imaging holds particular promise for coherent phonon−polariton wavepacket control using spatiotemporal femtosecond pulse shaping.