{"id":167,"date":"2026-06-17T13:42:54","date_gmt":"2026-06-17T17:42:54","guid":{"rendered":"https:\/\/sites.bu.edu\/karkarelab\/?page_id=167"},"modified":"2026-06-17T13:45:22","modified_gmt":"2026-06-17T17:45:22","slug":"tech","status":"publish","type":"page","link":"https:\/\/sites.bu.edu\/karkarelab\/tech\/","title":{"rendered":"Technology and Lab"},"content":{"rendered":"<p>Our work in experimental cosmology often requires us to build new instruments and detector technologies from scratch.<\/p>\n<h3>On-Chip Millimeter-Wave Spectrometers<\/h3>\n<p>Line intensity mapping (LIM) at millimeter wavelengths requires\u00a0<strong>spectroscopy<\/strong> 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 <em>on-chip<\/em> 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.<\/p>\n<p>In 2025 we deployed <strong>SuperSpec\u00a0<\/strong>&#8211; our first prototype on-chip spectrometer, covering 190-300 GHz with R~200 spectral resolution &#8211; 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!<\/p>\n<h3>Waveguide Spectrometers<\/h3>\n<p>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\u00a0<strong>waveguide spectrometers<\/strong>, which orient the spectrometer out of the focal plane to allow more efficient use of focal plane area, and enable much higher spectral resolution.<\/p>\n<h3>Boston University Lab<\/h3>\n<p>Our lab in the <a href=\"https:\/\/maps.app.goo.gl\/5qwadU7BcjVTaGbq8\">Physics Research Building<\/a> (PRB 270) is designed to test millimeter-wave detectors in multiple configurations before deployment in a telescope:<\/p>\n<ul>\n<li>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.<\/li>\n<li>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.<\/li>\n<li>We make extensive use of the Boston University <a href=\"https:\/\/www.bu.edu\/photonics\/sharedfacilities\/opf\/\">Optoelectronic Processing Facility<\/a> for spectrometer fabrication and the <a href=\"http:\/\/sif.bu.edu\/\">Scientific Instrument Facility<\/a> for machine shop work.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>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\u00a0spectroscopy 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 [&hellip;]<\/p>\n","protected":false},"author":24451,"featured_media":0,"parent":0,"menu_order":4,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/pages\/167"}],"collection":[{"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/users\/24451"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/comments?post=167"}],"version-history":[{"count":4,"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/pages\/167\/revisions"}],"predecessor-version":[{"id":174,"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/pages\/167\/revisions\/174"}],"wp:attachment":[{"href":"https:\/\/sites.bu.edu\/karkarelab\/wp-json\/wp\/v2\/media?parent=167"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}