Design and performance of a terahertz Fourier transform spectrometer for axion dark matter experiments

Abstract

Dedicated spectrometers for terahertz radiation with [0.3, 30] THz frequencies using traditional optomechanical interferometry are substantially less common than their infrared and microwave counterparts. This paper presents public documentation for the design and initial performance measurements of a tabletop Fourier transform spectrometer (FTS) for terahertz spectral analysis using infrared optics in a Michelson arrangement. This is coupled to a broadband pyroelectric photodetector designed for [0.1, 30] THz frequencies. We measure spectra of narrowband and broadband input radiation to characterize the performance of this instrument above 10 THz, where signal-to-noise is high. This device is constructed in the context of research-and-development for the recently-proposed Broadband Reflector Experiment for Axion Detection (BREAD), where the optical components can be applied to ongoing efforts for testing the pilot experiment.