Terahertz polaritonics: automated spatiotemporal control over propagating lattice waves

Automated spatiotemporal coherent control over propagating terahertz waves in crystalline solids is demonstrated. Mixed electromagnetic/lattice vibrational waves, called phonon-polaritons, are generated through femtosecond pulse irradiation of one region of a polar crystal, monitored through spatiotemporal imaging as they propagate within the crystal at light-like speeds, and manipulated through time-delayed femtosecond pulse irradiation of distinct crystalline regions. The temporally and spatially tailored optical waveforms that are used can be generated through automated spatiotemporal pulse shaping. The methods permit extensive control over high-frequency lattice dynamics. They also form the basis for terahertz polaritonics, through which complex terahertz-frequency waveforms and signals can be synthesized and processed. (C) 2001 Elsevier Science B.V. All rights reserved.