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.Index Terms-Sub-mm wavelengths, focal plane array, frequency selective absorber, incoherent source.

Thermal kinetic inductance detectors for millimeter-wave detection

“…TKIDs have been developed as energy detectors for x-ray imaging spectroscopy 41 to simultaneously achieve high spatial and energy resolution and for thermal x-ray photon detection. 42 TKIDs have also been used as THz radiation detectors [43][44][45][46] operating at Kelvin-range temperatures. However, TKIDs have not yet been demonstrated as power detectors for millimeter-wave instruments that operate at sub-Kelvin temperatures.…”

Roadmap of Terahertz Imaging 2021

“…Ref. [414] reports development of such superconducting detector arrays for two frequency bands (0.1-0.45 THz and 0.45-0.625 THz). An unprecedentedly large number of 8208 membrane-mounted detectors was implemented on six tiles, forming an exceptionally large focal plane array with a diameter of 24 cm.…”

A Passive, Fully Staring THz Video Camera Based on Kinetic Inductance Bolometer Arrays

“…This can be compared to Eq. (1), which gives a correspondence to diffraction-limited performance with a point frequency of 400 GHz while the comparison to truly wide-band detection is more involved [27]. However, the spots become asymmetrical towards the FPA edge which can be seen as an increase of the FWHM value in y-direction, yet being well below 30 mm for the whole FOV.…”