Ultrafast interactions in condensed matter as source of terahertz-frequency electromagnetic radiation

Terahertz (THz, 1012 Hz) frequency radiation has long proven to be elusive relative to microwaves at lower frequenc ies and infrared radiation at higher frequencies. We have investigated several solid-state materials as candidate terahertz-frequency emitters under excitation by ultra-short (12 fs) pulses of near-infrared radiation, and present the results here with a comparison between different emission mechanisms.