Pixel design for FIR/mm/submm astronomy constituted of a set of antenna-coupled superconducting detectors feeding a metamaterial-based lenslet

Astronomy in the millimetre and sub-millimetre spectrum aims at unveiling the processes behind the origin and evolution of our Universe at various scales, from protostars to the Cosmic Microwave Background. To carry out such observations, novel imaging and spectroscopy instruments covering the Tera-Hertz range are needed. At present, high-resolution spectroscopy is carried out with heterodyne detectors, using either Superconductor-Insulator-Superconductor-mixers or Hot-Electron Bolometer mixers, inherently limited in bandwidth and difficult to multiplex. Imaging is accomplished with detectors working near photo-noise level, primarily Transition Edge Sensors or Microwave Kinetic Inductance Detectors arrays, for which the focal optics needs scaling to reach the sensitivity needed for future cosmology experiments. In this work, the simulated design of a single pixel constituted of a set of antenna-coupled detectors receiving the light focused by a metamaterial-based phase-engineered lenslet is presented. This technology relies on standard lithography fabrication techniques and enables compact and broadband imaging and spectroscopy on-chip.