This paper reviews and summarizes the progress in research on high-T c 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-T c HEBs are given.
A 2 2 array of YBa 2 Cu 3 O 7 (YBaCuO) transition edge bolometers has been fabricated on an MgO substrate. The bolometers are of the meander type with line width and line spacing of 40 m. The meander length of a single bolometer is 12.5 mm, covering an area of 1 mm 1 mm. The voltage responsivity of each pixel, at 10 m wavelength, has been studied as a function of modulation frequency. The array exhibits a uniform response and an electrical noise equivalent power (NEP) of 4.2 10 12 W/ Hz or an optical NEP of 1 10 9 W/ Hz. Thermal crosstalk between adjacent pixels has been also studied and first imaging results are presented.
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