Integrated 585 GHz hot-electron bolometer mixers and focal-plane arrays for imaging applications

Astronomic and atmospheric remote sensing in the THz region have driven the demand for highly-sensitive mixers/receivers and focal-plane imaging arrays. Niobium hot-electron bolometers (HEB's) have received much attention in recent years owning to their merits such as broad IF bandwidth, high sensitivity and frequency scalability.; We have designed and fabricated prototype 585 GHz niobium HEB mixers on silicon wafers. The HEB's are integrated into annular slot antennas that incorporate low-pass filters (LPF's). DC test results, including R-T and I-V measurements, indicate successful fabrication of the HEB's. RF and Y-factor measurements have been performed and a mixer conversion gain of -11.9 dB and a DSB receiver noise temperature of ∼650 K have been achieved.; In order to optimize the single element HEB mixer design and facilitate the expansion of the single mixer into a full mixer array, the induced EMF method has been applied to analyze the embedding impedance of the single annular slot antenna presented to the HEB bolometer device. Excellent agreement between the EMF analysis and the measurements has been obtained. This approach has been further expanded to analyze annular slot antenna arrays, and calculation results are presented and discussed.; 585 GHz annular slot antenna coupled HEB imaging focal-plane arrays have been designed and fabricated on the basis of previous simulation and experiment results. Initial imaging experiment results are presented and show excellent agreement with theory and simulation data, demonstrating that a diffraction-limited imaging with a resolution of ∼2.75 mm has been achieved at 585 GHz. Y-factor measurements show that DSB mixer noise temperatures of 1675 K and 3517 K, with mixer conversion gain of -14.73 dB and -17.74 dB, respectively, have been obtained for two adjacent elements in a one-D focal-plane mixer array, which is comparable to the results reported in the literature.; To our best knowledge, the HEB imaging mixer array described in this dissertation is the first HEB heterodyne focal-plane mixer array reported based on the "reverse-microscope" architecture. With this architecture, a diffraction-limited imaging is achievable and this provides an alternative approach for developing large focal-plane mixer arrays in the THz region.