Spectral focusing dual-comb coherent anti-Stokes Raman spectroscopic imaging

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 antiStokes 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.

Broadband Coherent Raman Scattering Microscopy

“…The dual comb approach has also been used by Chen et al. in combination with SF to take advantage of a more efficient excitation with respect to the previous FT dual comb CARS implementations. Recently, the dual‐comb approach has been extended to a fiber‐format laser system, based on two Yb‐fiber oscillators followed by spectral broadening in a PCF, to generate sub‐20‐fs pulses …”

Two-dimensional electronic spectroscopy of bacteriochlorophyll a with synchronized dual mode-locked lasers

“…Although the automatic time delay scanning scheme referred to as ASOPS was proposed and demonstrated in 1987, 26 the application of ASOPS to coherent multidimensional spectroscopy has not been achieved, even though the ASOPS has been employed in the development of dual-frequency comb spectroscopic techniques. 27,28 Recently, synchronized MLs without photodetector array nor mechanical timedelay devices have been used to perform Raman microspectroscopy 29,30 , dual-frequency comb 2DES 31 , and time-and frequency-resolved transient absorption and refraction spectroscopy [32][33][34] .…”

Surface‐Enhanced Dual‐Comb Coherent Raman Spectroscopy with Nanoporous Gold Films

“…Dual‐comb coherent anti‐Stokes Raman spectroscopy (CARS) circumvents these difficulties by providing a motionless multi‐photon pump–probe scheme, combing high resolution reaching the intrinsic linewidth of Raman transitions, short measurement times down to a few microseconds, high contrast against spectral background due to time and frequency filtering, and simultaneous detection, with a single detector, of a broadband spectrum. This multiheterodyne technique has been refined by further developments respecting rapidness and broad bandwidth possibly covering the entire molecular fingerprint region (400–3300 cm −1 ) .…”