作者： Kun Chen, Tao Wu, Yan Li,Haoyun Wei
Coherent anti-Stokes Raman scattering (CARS) spectroscopy is a noninvasive and chemically specific for studying inhomogeneous systems. However, the complicating influence of the nonresonant response on the CARS signal severely limits its sensitivity and specificity and especially limits the extent to which CARS has been used as a fully quantitative tool. We establish a dual-soliton Stokes based coherent anti-Stokes Raman scattering (CARS) spectroscopy scheme capable of quantifying the sample molecular concentration and chemical composition within inhomogeneous samples, using a single fiber laser.
This dual-soliton CARS scheme utilizes a differential configuration to achieve efficient suppression of nonresonant background and therefore allows extraction of quantitative composition information. Besides, our all-fiber based excitation source can probe the most fingerprint region (1100–1800 cm–1) with a spectral resolution of 15 cm-1 under the spectral focusing mechanism, where is considerably more information contained throughout an entire spectrum than at just a single frequency within that spectrum. Quantitative capability is experimentally demonstrated by the determination of oleic acid concentration based on the linear dependence of signal on different Raman vibration bands.The combination of compact excitation source and background-free capability opens new opportunities for quantitative compositional analysis of different species within biological and material system.