Phase-controlled dual-comb coherent anti-Stokes Raman spectroscopic imaging

TL;DR

This paper introduces a dual-comb coherent anti-Stokes Raman spectroscopic imaging method that achieves high-resolution, broadband, and rapid chemical imaging, overcoming previous trade-offs between speed and specificity in biological systems.

Contribution

A novel dual-comb scheme with spectral focusing enables fast, high-resolution vibrational imaging across a broad spectral range in complex living systems.

Findings

Sub-microsecond vibrational measurement over 700 cm-1 spectral span

High signal-to-noise ratio in rapid imaging

Demonstrated imaging of chemical distributions in plant cells

Abstract

Coherent Raman microscopy provide label-free imaging by interrogating the intrinsic vibration of biomolecules. Nevertheless, trade-off between high chemical-specificity and high imaging-speed currently exists in transition from spectroscopy to spectroscopic imaging when capturing dynamics in complex living systems. Here, we present a novel concept in dual-comb scheme to substantially beat this trade-off and facilitate high-resolution broadband coherent anti-Stokes Raman spectroscopic imaging based on down-converted, automatically varying delay-time in spectral focusing excitation. A rapid measurement of vibrational microspectroscopy on sub-microsecond scale over a spectral span ~700 cm-1 with solid signal-to-noise ratio provides access to well-resolved molecular signatures within the fingerprint region. We demonstrate this high-performance spectroscopic imaging of spatially inhomogeneous distributions of chemical substances as well as the carotenoids accumulation in plant cells. This technique offers an unprecedented route for broadband CARS imaging with hundreds of kHz frame rate using available 1-GHz oscillators.