title: Coherent anti-Stokes Raman scattering microscopy imaging with suppression of four-wave mixing in optical fibers.
abstract: We demonstrated an optical fiber delivered coherent anti-Stokes Raman scattering (CARS) microscopy imaging system with a polarization-based mechanism for suppression of four-wave mixing (FWM) signals in delivery fiber. Polarization maintaining fibers (PMF) were used as the delivery fiber to ensure stability of the state of polarization (SOP) of lasers. The pump and Stokes waves were coupled into PMFs at orthogonal SOPs along the slow and fast axes of PMFs, respectively, resulting in a significant reduction of FWM signals generated in the fiber. At the output end of PMFs, a dual-wavelength waveplate was used to realign the SOPs of the two waves into identical SOPs prior to their entrance into the CARS microscope. Therefore, it allows the pump and Stokes waves with identical SOPs to excite samples at highest excitation efficiency. Our experimental results showed that this polarization-based FWM-suppressing mechanism can dramatically reduce FWM signals generated in PMFs up to approximately 99%. Meanwhile, the PMF-delivered CARS microscopy system with this mechanism can still produce high-quality CARS images. Consequently, our PMF-delivered CARS microscopy imaging system with the polarization-based FWM-suppressing mechanism potentially offers a new strategy for building fiber-based CARS endoscopes with effective suppression of FWM background noises.
authors.affiliation: Bioengineering and Informatics Program, The Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, Texas 77030, USA. Zhwang@ieee.org
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Gao
authors.forename: Pengfei
authors.initials: P
authors.lastname: Luo
authors.forename: Yaliang
authors.initials: Y
authors.lastname: Yang
authors.forename: Ahmad A
authors.initials: AA
authors.lastname: Hammoudi
authors.forename: Kelvin K
authors.initials: KK
authors.lastname: Wong
authors.forename: Stephen T C
authors.initials: ST
authors.lastname: Wong
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007089:Image Enhancement / Q000295:instrumentation*; D008027:Light; D008853:Microscopy / Q000295:instrumentation*; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*