Background-Free Stimulated Raman Microscopy with a Broadband Frequency-Modulation Scheme

Stimulated Raman scattering (SRS) microscopy is often regarded as a background-free technique due to the absence of the non-resonant background found in coherent anti-Stokes Raman scattering (CARS) microscopy. However, other optical processes - such as cross-phase modulation (XPM), thermal lensing (TL) and two-color-two-photon absorption (TCTPA)- can spectrally overlap with the resonant Raman signal, introducing a background signal that can limit the contrast and sensitivity of SRS measurements [1].