Coherent anti-Stokes Raman scattering (CARS) can be used to identify biological molecules from their vibrational spectra in tissue. A single double-chirped broadband optical pulse can excite a broad spectrum of resonant molecular vibrations in the fingerprint spectral region. Such a pulse also excites nonresonant CARS, particularly from water. We describe a theoretical technique to design an optical pulse to selectively excite coherent vibrations in a target molecular species so that the CARS signal generated is increased. The signal from other molecules is reduced, since the incident pulse does not excite them to have coherent vibrations. As an example, we apply the technique to design pulses to elicit increased CARS signal from a mixture of one or more of the alcohols methanol, ethanol, and isopropanol. We also show how such pulse designs can be used to selectively excite one member of closely related complex biological species. As measured interferometrically, the CARS signal from three phosphodiester stretch modes of DNA can be increased to more than ten times that of the analogous signal from RNA when the pulse design technique is used.

Original languageEnglish (US)
Article number718311
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
StatePublished - 2009
EventMultiphoton Microscopy in the Biomedical Sciences IX - San Jose, CA, United States
Duration: Jan 25 2009Jan 27 2009


  • Coherent anti-Stokes Raman scattering (CARS)
  • Nonlinear interferometric vibrational imaging (NIVI)
  • Optical pulse shaping

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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