Coherent Raman Scattering (CRS) is a powerful non-invasive microscopy technique, enabling label-free imaging of tissues and cells at high speed. A popular form of CRS is Coherent Anti-Stokes Raman Scattering (CARS) [1], which has the advantage of being a background-free process, but has the following drawbacks: it presents a non-resonant background (NRB), which distorts the resonant signal of interest, and it scales as the square of concentration N, preventing detection of dilute species. On the other hand, Stimulated Raman Scattering (SRS) is inherently free from NRB, scales as N but it measures a weak differential transmission signal sitting on the large background, thus requiring sophisticated high-speed modulation and lock-in detection [2]. Here we introduce balanced-detection Raman Induced Kerr Effect (BD-RIKE) as a novel CRS technique which combines the advantages of SRS (absence of NRB, linear scaling with the concentration) and CARS (background-free signal). RIKE relies on the Raman-induced birefringence occurring when the pump-Stokes frequency detuning is in resonance with a vibrational transition, leading to a polarization rotation of the Stokes field that we measure using a balanced detection configuration [3].
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