Multiplexed sub-Doppler spectroscopy with an optical frequency comb

TL;DR

This paper demonstrates a rapid, multiplexed sub-Doppler spectroscopy technique using an optical frequency comb generated by an electro-optic modulator, enabling simultaneous observation of hyperfine transitions in atomic potassium within microseconds.

Contribution

It introduces a novel method for sub-Doppler spectroscopy with an optical frequency comb that allows fast, simultaneous measurement of hyperfine transitions without slow scanning or prior frequency knowledge.

Findings

Hyperfine transitions observed simultaneously with 200 kHz spacing

Interferograms recorded in as little as 5 microseconds

Sub-Doppler features measured within the Doppler profile without scanning

Abstract

An optical frequency comb generated with an electro-optic phase modulator and a chirped radiofrequency waveform is used to perform saturation and pump-probe spectroscopy on the $D_1$ and $D_2$ transitions of atomic potassium. With a comb tooth spacing of 200 kHz and an optical bandwidth of 2 GHz the hyperfine transitions can be simultaneously observed. Interferograms are recorded in as little as 5 $\mu$s (a timescale corresponding to the inverse of the comb tooth spacing). Importantly, the sub-Doppler features can be measured as long as the laser carrier frequency lies within the Doppler profile, thus removing the need for slow scanning or a priori knowledge of the frequencies of the sub-Doppler features. Sub-Doppler optical frequency comb spectroscopy has the potential to dramatically reduce acquisition times and allow for rapid and accurate assignment of complex molecular and atomic spectra which are presently intractable.