Concept of a mixer based on a cold-electron bolometer

A phase-sensitive terahertz heterodyne mixer of a new type based on a cold-electron bolometer is proposed. In this mixer, a normal-metal thin-film absorber is connected to a planar antenna via superconductor-insulator-normal metal (SIN) tunnel junctions, thus forming a SINIS structure. The SINIS mixer combines the advantages of a hot-electron bolometer (HEB), such as a high signal frequency at a small local oscillator power, with the advantages of an SIS mixer, including low noise level, a high intermediate frequency, and wide working temperature range (up to a critical temperature of the superconductor). In contrast to the HEB and SIS mixers, the proposed device is less sensitive to external magnetic noise and exhibits no additional noise related to the superconducting transition and the Josephson effect.