Sensitivity improvement of dual-comb spectroscopy using mode-filtering technique

In this study, we demonstrated an improvement in the detection sensitivity of dual-comb spectroscopy using the repetition rate multiplication of optical frequency combs. We compared the dual-comb signals in three dual-comb setups consisting of combinations of two combs with and without mode-filtering, and investigated how the repetition rate influences the signal-to-noise ratio (SNR) of dual-comb measurements. The dual-comb setups using high-repetition-rate combs enabled the absorption lines of HCN gas to be measured with a high SNR in a short averaging time, and real-time spectral data acquisition was realized using a low-sensitivity and low-resolution RF spectrum analyzer.