Quantum-noise-limited optical frequency comb spectroscopy

TL;DR

This paper demonstrates a quantum-noise-limited optical frequency comb spectroscopy system achieving unprecedented sensitivity and resolution, enabling rapid, high-precision molecular absorption measurements.

Contribution

The authors developed a cavity-enhanced frequency comb spectroscopy system reaching the highest sensitivity for comb-based techniques, combining a high-finesse cavity, fast Fourier transform spectrometer, and ultra-low-noise detection.

Findings

Achieved absorption sensitivity of 1.7×10⁻¹² cm⁻¹ per spectral element.

Spectra with SNR above 1000 acquired within seconds.

Measured lineshapes match theoretical predictions.

Abstract

We achieve a quantum-noise-limited absorption sensitivity of 1.7/times10$^{-12}$ cm$^{-1}$ per spectral element at 400 s of acquisition time with cavity-enhanced frequency comb spectroscopy, the highest demonstrated for a comb-based technique. The system comprises a frequency comb locked to a high-finesse cavity and a fast-scanning Fourier transform spectrometer with an ultra-low-noise autobalancing detector. Spectra with a signal-to-noise ratio above 1000 and a resolution of 380 MHz are acquired within a few seconds. The measured absorption lineshapes are in excellent agreement with theoretical predictions.