Technology and Lab

Our work in experimental cosmology often requires us to build new instruments and detector technologies from scratch.

On-Chip Millimeter-Wave Spectrometers

Line intensity mapping (LIM) at millimeter wavelengths requires spectroscopy to resolve cosmic structure as a function of redshift. Contemporary mm-wave spectrometers (e.g., diffraction gratings or heterodyne recievers) are bulky or limited in bandwidth, and are difficult to scale up. Our group is pioneering the use of on-chip spectrometers, in which the spectral separation is done entirely on a silicon wafer. Using thin-film superconductors and techniques from CMB detector fabrication, our planar filter-bank technology promises to enable next-generation LIM focal planes with the sensitivity for LIM cosmology.

In 2025 we deployed SuperSpec – our first prototype on-chip spectrometer, covering 190-300 GHz with R~200 spectral resolution – to the Large Millimeter Telescope on the Volcan Sierra Negra in Mexico. Analysis of these data is underway. Stay tuned for results, including detection of emission lines in nearby galaxies!

Waveguide Spectrometers

While SuperSpec and SPT-SLIM already offer a dramatic sensitivity increase over previous technologies, they are still not as efficient as they could be. We are also developing waveguide spectrometers, which orient the spectrometer out of the focal plane to allow more efficient use of focal plane area, and enable much higher spectral resolution.

Boston University Lab

Our lab in the Physics Research Building (PRB 270) is designed to test millimeter-wave detectors in multiple configurations before deployment in a telescope:

• Our BlueFors helium dilution refrigerator, equipped with multiple RF lines and windows/filters, allows us to probe superconducting detector physics with dark measurements and optically with configurations that simulate what they will experience on sky.
• Our millimeter-wave optics bench, equipped with a free-space mm-wave vector network analyzer and a Fourier Transform spectrometer, allows for warm tests of waveguide spectrometers and mm-wave optics.
• We make extensive use of the Boston University Optoelectronic Processing Facility for spectrometer fabrication and the Scientific Instrument Facility for machine shop work.