Avoidance of four-wave mixing in optical fiber bundle for coherent anti-Stokes Raman scattering endomicroscopy

We propose and demonstrate a method of suppressing four-wave mixing (FWM) in an optical fiber bundle to realize coherent anti-Stokes Raman scattering (CARS) endomicroscopy, which is the leading candidate for a definitive diagnosis of gastrointestinal cancer. Two excitation laser beams with different wavelengths are delivered via different cores to suppress FWM and are then combined with a polarization prism and a dual-wavelength wave plate and are focused to a spot. The background emission from the optical fiber bundle was suppressed to 1/3289, and we demonstrated CARS imaging of a polystyrene bead using the proposed method.