Distributed antenna-coupled TES for FIR detector arrays

We report progress toward large arrays of sensitive TES bolometers for submillimeter and far-infrared wavelengths with noise equivalent power (NEP) suitable for either imaging from a cooled space telescope or ground based spectroscopy. The arrays are based on a pixel design that makes use of a distributed transition edge sensor (TES) coupled to a slot antenna array. We have electrically characterized prototype detectors consisting of 256 TiN hot-electron TES microbolometers biased in parallel with T c =50 mK. The measured electron-phonon thermal conductance of prototype devices is as low as 1.1 pW/K at 50 mK corresponding to an electrical NEP of 4×10⁻¹⁹ W/Hz½. The time constant of two detectors with different geometries and transition widths was measured under a range of bias conditions. We have measured time constants ≳10⁻³ seconds, which is long enough for straightforward multiplexing with existing multiplexer technology