Comb-mode-resolving broadband Fourier transform spectroscopy

Abstract

This report demonstrates progress made to develop a robust turn-key astrocomb architecture for the calibration package of the HIRES spectrograph planned for installation on the upcoming Extremely-Large Telescope (ELT) which intends to enable novel research across a range of scientific disciplines. Here, we demonstrate progress towards a laser frequency comb covering optical and infra-red wavelength ranges and made possible by use of nonlinear interactions driven by a single stabilised mode-locked laser source. We also detail a proof-of-concept experiment carried out with a compact broadband Fourier-transform spectrometer to identify the subset of filtered frequency-comb modes, an important ancillary technology for any future broadband Fabry-P´erot-based astrocomb.