Proposal Number: ECS-9623893 Principal Investigator: Mark Lee CAREER: Application of a High Tc Superconductor for Large Bandwidth Far-Infrared Mixing Receivers Superconductors have a uniquely sensitive and rapid quantum mechanical response to electromagnetic radiation near the gap frequency. The new high Tc cuprate superconductors posses an effective gap at least ten times that of Nb therefore allowing access to the higher frequency far-infrared regime, 1 to 10 THz, for the first time. This is a region in which the electromagnetic frequencies are beyond the optical range for conventional receivers. Also recent experiments show that the response bandwidth of the high Tc receivers can exceed 40 GHz, a ten-fold improvement of any existing technology. This will vastly increase the amount of information which can be carried in the THz band. The physical principles governing the electrodynamics o these superconductors are still unsettled. This work will simultaneously elucidate fundamental aspects of thigh Tc superconductivity while advancing practical detectors to fill this technological void he electromagnetic spectrum.