SuperSpec: On-Chip Spectrometer Design, Characterization, and Performance

Abstract

SuperSpec is an integrated, on-chip spectrometer for millimeter and sub-millimeter astronomy intended to pave the way for large-scale, multi-beam spectrometer instruments. SuperSpec is demonstrating a three beam, dual-polarization instrument for observing star formation in distant galaxies on the Large Millimeter Telescope , a 50 m telescope on Volcan Sierra Negra in Mexico. SuperSpec provides moderate resolution ( $$R \sim 270-290$$ ) in the 1 mm atmospheric window (200–300 GHz) with a lithographically patterned filterbank on a 3.5 cm x 5.5 cm chip. The filterbank intended for deployment is implemented in niobium, fed by a lensed antenna, and using a extremely low-volume ( $$2.6 \mu m^3$$ ) titanium nitride lumped element kinetic inductor detectors (LEKIDs) as the sensors. The small size of the spectrometer and inherent multiplexibility of the kinetic inductance detectors will allow the future use of SuperSpec in larger, multi-pixel/multi-object spectrometers far beyond the three-pixel spectrometer being demonstrated soon. We report the design of the spectrometer, laboratory characterization of devices for the upcoming SuperSpec deployment. This involves laboratory testing of the filterbank spectral response, and observing noise in the TiN KIDs.