Open AccessRaman Microscopy based on Doubly-Resonant Four-Wave Mixing (DR-FWM)
Author(s) -
Tyler Weeks,
Sebastian WachsmannHogiu,
Thomas Huser
Publication year - 2009
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.017044
Subject(s) - raman scattering , raman spectroscopy , microscopy , four wave mixing , coherent anti stokes raman spectroscopy , optics , resonance (particle physics) , materials science , mixing (physics) , nonlinear optics , physics , laser , atomic physics , quantum mechanics
Doubly-resonant four-wave mixing (DR-FWM) is a nondegenerate four-wave mixing process in which four photons interact to coherently probe two distinct Raman resonances. We demonstrate DR-FWM microscopy as a label-free and nondestructive molecular imaging modality with high chemical specificity on the submicron scale by imaging alkyne-substituted oleic acid in both aqueous and lipid-rich environments. DR-FWM microscopy is contrasted to coherent anti-Stokes Raman scattering (CARS) microscopy and it is shown that the coherent addition of two simultaneously probed Raman resonances leads to a significant increase in signal without increasing the non-resonant background. Thus, this scheme enables the detection of weak Raman signals through amplification by a strong Raman resonance, potentially increasing the overall detection sensitivity beyond what has been demonstrated by either CARS or stimulated Raman scattering (SRS).