Optimization of the Microwave Properties of the Kinetic-Inductance Bolometer (KIBO)
in: IEEE Transactions on Applied Superconductivity (2017)
Silicon nitride membrane based cryogenic bolo-meters exhibit high sensitivity and enable ultra-sensitive detector applications. Multi-pixel instruments were already introduced as devices for submillimeter-wave imaging. Nevertheless, the numbers of pixels are limited by the readout process which is typically a time- or code-division multiplexing (TMD or CDM) technique. To overcome this challenge a replacement of the transition-edge sensor (TES) as thermometer by a lumped-element resonance circuit seems to be a promising solution. Therefore, one can benefit by the intrinsic capability of frequency-division multiplexing (FDM) which allows the simultaneous readout of large detector arrays in real-time. The number of pixels is then limited by the available readout bandwidth and the quality factors of each individual resonance circuit. Based on our feasibility study we successfully demonstrated the principal operation of such a device, which we call kinetic-inductance bolometer (KIBO). However, the overall performance of the achievable noise-equivalent power (NEP) was limited by design implementation. Redesigned devices were fabricated with niobium thin-film technology and we estimate the improvement of the NEP value.