Design and fabrication of two-dimensional superconducting bolometer arrays

We have been developing an architecture for producing large format, two-dimensional arrays of close-packed bolometers, which will enable far-infrared to millimeter wavelength (λ=100 μm-2 mm) cameras and spectrometers to obtain images and spectra orders of magnitude faster than present instruments. The low backgrounds achieved in these instruments require very sensitive detectors with NEPs ranging from 10 ^-17 to 10 ^-19 W/√Hz. Superconducting transition edge sensor bolometers can be close-packed using the Pop-Up Detector (PUD) format, and SQUID multiplexers operating at the detector base temperature can be intimately coupled to them. The array unit cell is 8×32 pixels, using 32element detector and multiplexer components. We have fabricated an engineering model array with this technology featuring a very compact, modular approach for large format arrays. We report on the production of the 32-element components for the arrays. Planned instruments using this array architecture include the Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory, the South Pole Imaging Fabry-Perot Interferometer (SPIFI) for the AST/RO observatory, the Millimeter Bolometer Camera for the Atacama Cosmology Telescope (MBC/ACT), and the Redshift "Z" Early Universe Spectrometer (ZEUS).