Design, Fabrication and Characterization of a Submillimeter-Wave Niobium HEB Mixer Imaging Array Based on the “Reverse-Microscope” Concept

Abstract

Prototype one-dimensional (1-D) superconducting hot-electron bolometer (HEB) imaging mixer arrays with four pixels, designed for operation at 585 GHz, and based on slot-ring antennas arranged in the "reverse-microscope" configuration have been fabricated and implemented. Electromagnetic simulations with Agilent's Momentum software package have been performed to study the self-and mutual-impedances of the slot-ring antenna (SRA) array corresponding to various element spacings. Moreover, the element SRA off-axis radiation patterns (with an extended silicon lens) have been calculated using ray-tracing techniques and the imaging angular resolution has been predicted. Fabrication of the arrays and HEB elements are discussed, and measurements for a single mixer element are presented, yielding a double sideband (DSB) receiver noise temperature of approximately 650 K at 585 GHz.

Design Optimization of Silicon-Based Optically Excited Terahertz Wave Modulation

“…At the same time, with different wavelengths of excitation light, the absorption coefficient α and reflectivity e R of silicon also change, thus affecting the generation of photogenerated carriers, which in turn has an impact on the performance of the THz modulator. Figure 8 shows the absorp tion coefficient α and reflectance ex R of silicon at different excitation light wavelengths [32]. Figure 9a shows the variation of THz wave reflectivity R for different excitation wave lengths and power densities P. Figure 9b shows the variation of MD for different excitation wavelengths ex λ and power densities P. It can be seen that with the increasing excitation optical power, the THz reflection R will show the characteristic of decreasing firstly and then increasing rapidly.…”