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 vibrat ional waves, called phonon-polaritons, are generated through femtosecond pu lse irradiation of one region of a polar crystal, monitored through spatiot emporal imaging as they propagate within the crystal at light-like speeds, and manipulated through time-delayed femtosecond pulse irradiation of disti nct crystalline regions. The temporally and spatially tailored optical wave forms 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 whic h complex terahertz-frequency waveforms and signals can be synthesized and processed. (C) 2001 Elsevier Science B.V. All rights reserved.