Visible astro-comb filtered by a passively-stabilized Fabry-Perot cavity

TL;DR

This paper presents a compact visible astro-comb with high spectral coverage and stability, achieved through a passively-stabilized Fabry-Perot cavity and advanced filtering techniques, suitable for astronomical spectrograph calibration.

Contribution

The work introduces a stable, high-resolution visible astro-comb with a novel filtering method using a passively-stabilized Fabry-Perot cavity, enhancing spectral purity and stability.

Findings

Achieved a 29.3 GHz comb covering 560-700nm spectrum.

Demonstrated high-resolution spectral lines in an astronomical spectrograph.

Ensured comb stability with a Rb-clock-locked seed laser.

Abstract

We demonstrate a compact 29.3 GHz visible astro-comb covering the spectrum from 560nm to 700nm. A 837 MHz Yb:fiber laser frequency comb phase locked to a Rb clock served as the seed comb to ensure the frequency stability and high side mode suppression ratio. After the visible super-continuum generation, a cavity-length-fixed Fabry-Perot cavity made by ultra-low expansion glass was utilized to filter the comb teeth for eliminating the rapid active dithering. The mirrors were home-made complementary chirped mirrors pair with zero dispersion and high reflection to guarantee no mode skipping. These filtered comb teeth were clearly resolved in an astronomical spectrograph of 49,000 resolution, exhibiting sharp linetype, zero noise floor, and uniform exposure amplitude.