We explore strategies for optimizing selectivity, specificity, and sensitivity in broadband CARS by precalculating
pulse shapes using an evolutionary algorithm. We show the possibility of selective excitation of a single constituent
in a test case of a mixture of five resonant compounds. The obtainable contrast ratio for a test case
of PMMA in a mixture of five resonant compounds is predicted to be 2000:1, and is related the uniqueness of
the complex vibrational response of the compound of interest compared to that of the surrounding molecules.
Furthermore we investigate how the effects of homodyne mixing in the focal volume affect the obtainable contrast
ratio and how noise affects the optimization. We also show preliminary results of experimental optimization of
the CARS signal from PMMA microspheres, resulting in high contrast imaging, free of non-resonant background
By spectral phase shaping of both the pump and probe pulses in coherent anti-Stokes Raman scattering (CARS)
spectroscopy we demonstrate the extraction of the frequencies of vibrational lines using an unamplified oscillator.
Furthermore we demonstrate chemically selective broadband CARS microscopy on a mixed sample of 4 μm
diameter polystyrene (PS) and poly(methyl methacrylate) (PMMA) beads. The CARS signal from either the
PS or the PMMA beads is shown to be enhanced or suppressed, depending on the phase profile applied to the
broadband spectrum. Using a combination of negative and positive (sloped) π-phase steps in the pump and
probe spectrum the purely non-resonant background signal is removed.