Terahertz radiation cools quantum dot sensors
Several emerging applications of terahertz radiation, including chemical characterization of materials, communication, medical imaging and security screening, have stimulated intense research to access this region of the electromagnetic spectrum, where availability of sources and detectors is quite limited. In an upcoming issue of Nano Letters, Georgetown University scientists Dr. Mohamed Rinzan and Prof. Paola Barbara and their collaborators at the University of Maryland and Northwestern University report on a new, highly-sensitive detector of terahertz radiation. These detectors can determine the radiation frequency, unlike traditional detectors such as bolometers, and can easily detect femtowatts of power. By using on-chip antennas, the coupling of radiation to the detectors was dramatically increased. The work also shows a new, strikingly counterintuitive effect: exposure to radiation cools the sensors, which further improves their performance; bolometers and many other detectors are heated by exposure to radiation. These results can potentially be applied to graphene and pave the way to practical, highly sensitive terahertz spectral analyzers.