Tunable all-silicon Fabry–Perot spectrometer for submillimeter astronomy

In this paper, we present the development and experimental characterization of a cryogenic Fabry–Perot spectrometer, proposed for on-chip integration with submillimeter wave detectors. The Fabry–Perot interferometer design was chosen for its compactness, compatibility with polarimetric imaging, and versatile spectral resolution capabilities. By using dielectric Bragg mirrors, the presented Fabry–Perot mitigates the absorption losses typical of conventional metallic mesh mirrors, thereby enhancing transmission efficiency while keeping high finesse. We discuss the theoretical framework and performance considerations of a Fabry–Perot interferometer based on silicon Bragg reflectors and provide an analysis of spectral responses obtained from cryogenic optical measurements. These results demonstrate the potential of Bragg-mirror Fabry–Perot spectrometers as a viable approach for future medium- and high-resolution, multi-functional submillimeter imaging detection systems for ground- and space-based observatories.