A Dual-Band Focal Plane Array of Kinetic Inductance Bolometers Based on Frequency-Selective Absorbers

Abstract

Passive imaging cameras at submillimeter wavelengths with large format focal plane arrays (FPAs) are being developed as the next generation of security screening systems. In this contribution, a dual-band FPA for security imagers at submillimeter wave frequencies is presented. The detectors are based on bolometric superconducting kinetic inductance resonators, which allow the development of large FPAs at medium-cooled temperatures. Two frequency-selective absorber (FSA) sets coupled to superconductive resonator lines are designed to implement a dual-color security imager. The performance of the dual-band imager is evaluated using spectral analysis approach that combines Fourier optics with a Floquet-mode field representation. The geometry of the unit cells is based on a Jerusalem cross configuration and the designed FSAs show a stable angular response and a rejection 1 to 3 of the undesired bandwidth. The detectors in the dual-band FPA are distributed over a hexagonal grid to maximize their physical size and then improve their sensitivity. The effective point spread function of the imager coupled to a black-body point source over a wide frequency band (1:6) was demonstrated experimentally with excellent agreement to the one estimated by using the proposed spectral technique.