Cold-electron bolometer as a photon-noise-limited detector with on-chip electron self-cooling

摘要

After discovering the electron cooling by Super- conductor-Insulator-Normal metal (SIN) tunnel junc- tions, significant efforts were applied to obtain an ef- fective on-chip cooler for mm/IR detectors. We have developed a Cold-Electron Bolometer (CEB) with ef- fective direct electron self-cooling of the absorber [1], [2]. A photon-noise-limited pixel, consisting of an ar- ray of CEBs with self-cooling, is realized for OLIMPO Balloon Telescope for incoming power P in up to 60 pW at phonon temperature T ph = 310 mK. Operation of the bolometer at electron temperature less than phonon temperature significantly increases its sensitivity so that the noise equivalent power goes beyond the photon-noise-limited mode, which means that the internal bolometer noise is smaller than the noise of incoming signal [3]. We demonstrate the electron cooling from 310 to 120 mK without signal and from 410 to 225 mK for Pin = 60 pW at 350 GHz. The proposed technology is a potential replacement for the high-cost dilution refrigerators for space ap- plications.