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

TL;DR

This paper introduces a novel tabletop Fourier transform spectrometer for multi-terahertz radiation, demonstrating initial performance above 10 THz and discussing its potential for axion dark matter detection.

Contribution

It presents the design and initial performance of a terahertz Fourier transform spectrometer using infrared optics and broadband pyroelectric detectors, suitable for axion dark matter searches.

Findings

Effective measurement of spectra above 10 THz.

Potential for extending measurements below 10 THz.

Application to broadband axion dark matter detection.

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 the design and initial performance measurements of a tabletop Fourier transform spectrometer (FTS) for multi-terahertz radiation 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 paves the groundwork for planned upgrades to extend below 10 THz. We also briefly discuss potential astroparticle physics applications of such FTS instruments to broadband axion dark matter searches, whose signature comprises low-rate monochromatic photons with unknown frequency.