Ultra-high-speed coherent anti-Stokes Raman spectroscopy with a hybrid dual-comb source

TL;DR

This paper introduces a hybrid dual-comb CARS system that significantly increases spectroscopic imaging speed, enabling rapid chemical sensing and imaging in the high-wavenumber C-H stretching region.

Contribution

The authors develop a hybrid dual-comb CARS system combining a broadband fiber laser and a frequency-modulated electro-optic comb, achieving record-high refresh rates for spectroscopic imaging.

Findings

Achieved multiplex CARS spectra at 1 MHz refresh rate

Demonstrated fast CARS imaging of liquid mixtures

Enabled spectral measurements in high-wavenumber C-H region at unprecedented speed

Abstract

Coherent anti-Stokes Raman scattering (CARS) spectroscopy with time-delayed ultrashort pulses and a single-pixel photodetector has shown great potential for spectroscopic imaging and transient studies in chemistry and biological research. However, those systems rely on mechanical delay lines or two asynchronous optical combs with inflexible repetition frequencies, technically limiting their acquisition speeds. Here, we demonstrate a hybrid dual-comb CARS system involving a broadband fiber laser and a highly-flexible, frequency-modulated electro-optic comb. We achieve multiplex CARS spectra (2800-3200 cm-1), with a moderate resolution (22 cm-1), at a maximum refresh rate of 1 MHz, limited by the radio-frequency synthesizer we use. Fast spectroscopic CARS imaging is demonstrated for liquid mixtures. Our system enables spectral measurements in the high-wavenumber C-H stretching region at a record speed that is an order of magnitude higher than state-of-the-art systems, which may open up new opportunities for fast chemical sensing and imaging.