We describe a testbed to characterize the optical response of compact superconducting on-chip spectrometers in development for the Experiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) mission. EXCLAIM is a balloonborne far-infrared experiment to probe the CO and CII emission lines in galaxies from redshift 3.5 to the present. The spectrometer, called u-Spec, comprises a diffraction grating on a silicon chip coupled to kinetic inductance detectors (KIDs) read out via a single microwave feedline. We use a prototype spectrometer for EXCLAIM to demonstrate our ability to characterize the spectrometers spectral response using a photomixer source. We utilize an on-chip reference detector to normalize relative to spectral structure from the off-chip optics and a silicon etalon to calibrate the absolute frequency.
@article{arxiv.2312.07656,
title = {Optimization of an Optical Testbed for Characterization of EXCLAIM u-Spec Integrated Spectrometers},
author = {Maryam Rahmani and Emily M. Barrentine and Eric R. Switzer and Alyssa Barlis and Ari D. Brown and Giuseppe Cataldo and Jake A. Connors and Negar Ehsan and Thomas M. Essinger-Hileman and Henry Grant and James Hays-Wehle and Wen-Ting Hsieh and Vilem Mikula and S. Harvey Moseley and Omid Noroozian and Manuel A. Quijada and Jessica Patel and Thomas R. Stevenson and Carole Tucker and Kongpop U-Yen and Carolyn G. Volpert and Edward J. Wollack},
journal= {arXiv preprint arXiv:2312.07656},
year = {2023}
}