We present a new and simple approach to broadband coherent anti-Stokes Raman scattering (CARS) microscopy that yields background-free vibrational spectra. We present evidence for a mechanism where two different frequency components in a continuum pulse (pump/Stokes) populate molecules to vibrationally excited states and a subsequent narrowband pulse (probe) induces anti-Stokes Raman emission. This one-laser, two-pulse pump-probe configuration allows straightforward and complete suppression of the non-resonant contribution by delaying the second (probe) pulse. The resulting spectra exhibit background-free resonant peaks in the fingerprint region (<2000 cm-1).
Citation: Optics Letters
Pub Type: Journals
CARS, coherent anti-Stokes Raman scattering, non-invasive imaging, non-resonant background, optical microscopy, time-resolved spectroscopy