An array of cold-electron bolometers with SIN tunnel junctions and JFET readout for cosmology instruments

Abstract

A novel concept of the parallel/series array of Cold-Electron Bolometers (CEB) with Superconductor-Insulator-Normal (SIN) Tunnel Junctions has been proposed. The concept was developed specially for matching the CEB with JFET amplifier at conditions of high optical power load. The CEB is a planar antenna-coupled superconducting detector with high sensitivity. For combination of effective HF operation and low noise properties the current-biased CEBs are connected in series for DC and in parallel for HF signal. A signal is concentrated from an antenna to the absorber through the capacitance of the tunnel junctions and through additional capacitance for coupling of superconducting islands. Using array of CEBs the applications can be considerably extended to higher power load by distributing the power between N CEBs and decreasing the electron temperature. Due to increased responsivity the noise matching is so effective that photon NEP could be easily achieved at 300 mK with a room temperature JFET for wide range of optical power loads. The concept of the CEB array has been developed for the BOOMERanG balloon telescope and other Cosmology instruments. © 2008 IOP Publishing Ltd.