We report on the first observation of the emission of electromagnetic radiation from coherent lattice vibrations in a semiconductor. Coherent optical phonons are excited by ultrashort laser pulses in single-crystal tellurium. THz frequency radiation emitted by the Dember-field-driven phonons is detected by time-resolved THz-emission spectroscopy. The measurements are complemented by optical pump-probe experiments with a polarization-sensitive detection scheme utilizing the symmetry of the Raman tensor.

• Received 22 July 1994

DOI:https://doi.org/10.1103/PhysRevLett.74.738