Coherent anti-Stokes Raman scattering microscopy using photonic crystal fiber with two closely lying zero dispersion wavelengths.

We demonstrate coherent anti-Stokes Raman scattering (CARS) microscopy of lipid-rich structures using a single unamplified femtosecond Ti:sapphire laser and a photonic crystal fiber (PCF) with two closely lying zero dispersion wavelengths (ZDW) for the Stokes source. The primary enabling factor for the fast data acquisition (84 micros per pixel) in the proof-of-principle CARS images, is the low noise supercontinuum (SC) generated in this type of PCF, in contrast to SC generated in a PCF with one ZDW. The dependence of the Stokes pulse on average input power, pump wavelength, pulse duration and polarization is experimentally characterized. We show that it is possible to control the spectral shape of the SC by tuning the pump wavelength of the input pulse and the consequence for CARS microscopy is discussed.