Recent progress in high-temperature superconductor bolometric detectors: from the mid-infrared to the far-infrared (THz) range

This paper reviews and summarizes the progress in research on high-Tc superconducting infrared bolometers since the discovery of high-temperature superconductor (HTSC) materials. After mentioning previous review articles and their particular themes in the introduction, we recall bolometer basics in section 2, where key parameters are presented and design principles summarized. The latter include incident radiation to HTSC thermometer coupling techniques (absorber and antenna approaches) and the thermal balance inside the active region. Section 3 (which forms the largest part of the article) is devoted to medium and near-infrared transition edge bolometers (0.8-20 µm wavelength range), covering both monolithic and composite (absorber coupled) devices. The main landmarks and state-of-the-art devices are described in the order of the increasing degree of technological complexity (thick substrates, thinned or suspended substrates, micromachined silicon-based structures), while keeping in mind the sensitivity versus time response compromise and the aimed competitiveness with photon detectors. The last section treats far-infrared (antenna coupled) hot electron bolometers (HEBs), whose emergence has benefited from newly developed superconducting nanostructures and which are promising candidates for terahertz heterodyne detection. Finally, recent results on both HTSC and (more mature) low-Tc HEBs are given.