Optical Measurements of SuperSpec: A Millimeter-Wave On-Chip Spectrometer

• Published in: Journal of low temperature physics Vol. 176; no. 5-6; pp. 841 - 847
• Main Authors: Hailey-Dunsheath, S., Barry, P. S., Bradford, C. M., Chattopadhyay, G., Day, P., Doyle, S., Hollister, M., Kovacs, A., LeDuc, H. G., Llombart, N., Mauskopf, P., McKenney, C., Monroe, R., Nguyen, H. T., O’Brient, R., Padin, S., Reck, T., Shirokoff, E., Swenson, L., Tucker, C. E., Zmuidzinas, J.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2014
• Subjects: Channels; Characterization and Evaluation of Materials; Chips; Condensed Matter Physics; Detectors; Low temperature physics; Magnetic Materials; Magnetism; Optical measurement; Physics; Physics and Astronomy; Resonators; Spectral lines; Spectrometers; Spectroscopy; Kinetic inductance detector; Millimeter-wave
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-013-1068-2

SuperSpec is a novel on-chip spectrometer we are developing for (sub)millimeter wavelength astronomy. Our approach utilizes a filterbank of moderate resolution ( R ∼ 500 ) channels, coupled to lumped element kinetic inductance detectors (KIDs), all integrated onto a single silicon chip. The channels are half-wave resonators formed by lithographically depositing segments of superconducting transmission line, and the KIDs are titanium nitride resonators. Here we present optical measurements of a first generation prototype, operating in the 180–280 GHz frequency range. We have used a coherent source to measure the spectral profiles of 17 channels, which achieve linewidths corresponding to quality factors as high as Q filt = 700 , consistent with the designed values plus additional dissipation characterized by Q i ≈ 1440 . We have also used a Fourier Transform Spectrometer to characterize the spectral purity of all 72 channels on the chip, and measure typical out of band responses ∼ 30 dB below the peak response.