Design considerations for a background limited 350 micron pixel array using lumped element superconducting microresonators

Future submillimeter telescopes will demand arrays with similar to 10(6) pixels to fill the focal plane. MAKO is a 350 mu m camera being developed to demonstrate the use of superconducting microresonators to meet the high multiplexing factors required for scaling to large-format arrays while offering background-limited single-pixel sensitivity. Candidate pixel designs must simultaneously meet many requirements. To achieve the desired noise equivalent powers it must efficiently absorb radiation, feature a high responsivity, and exhibit low intrinsic device noise. Additionally, the use of high resonator quality factors of order similar to 10(5) and resonant frequencies of order f(res) approximate to 100 MHz are desirable in order to reduce the per-pixel bandwidth to a minimum set by telescope scan speeds. This allows a maximum number of pixels to be multiplexed in a fixed electronic bandwidth. Here we present measurement results of the first MAKO prototype array which meets these design requirements while demonstrating sufficient sensitivity for background-limited operation at ground-based, far-infrared telescopes.