Optimally chirped CARS using fiber stretchers

High spectral resolution coherent anti-Stokes Raman scattering (CARS) spectroscopy and microscopy are demonstrated with femtosecond laser systems. We perform optimal chirping in glass fibers and demonstrate a spectral resolution enhancement to better than 26 cm −1 , which is limited by the bandwidth of the measured resonances. Considering the convolution with the resonance bandwidth this corresponds to a spectral resolution of approximately 2.5 cm −1 , which is an enhancement by a factor of 165 with respect to the use of bandwidth-limited pulses. In microscopic imaging, a water background suppression of 81.5% is achieved.