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

Abstract

Passive imaging cameras at sub-millimeter wavelengths with large format focal plane arrays are being developed as the next generation of security screening systems. In this contribution, a dual-band focal plane array (FPA) for security imagers at submillimeter wave frequencies is presented. The detectors are based on bolometric superconducting kinetic inductance resonators, which allows 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.