title: Investigation of a four-wave mixing signal generated in fiber-delivered CARS microscopy.
abstract: We studied the nonlinear signal generated in the fiber at an anti-Stokes wavelength during the delivery of the picosecond (ps) pump and Stokes beams in coherent anti-Stokes Raman scattering (CARS) microscopy. A small non-phase-matched four-wave mixing (FWM) signal was prevalently observed in the fiber at the power level where other nonlinear processes, including self-phase modulation and cross-phase modulation, were well suppressed. We analyzed the features of the FWM signal generation by varying the location of temporal overlap between two input pulses in the fiber to compare this to the CARS signal generated in the sample. Numerical modeling based on the nonlinear Schrödinger equation was also conducted and clearly explains the results in the experiment. In addition, we experimentally verified the interferometric feature of this FWM signal with the CARS signal by employing a phase-shifting unit, which potentially suggests the use of the FWM signal as a local oscillator for the interferometric CARS system.
authors.affiliation: Fiber Optics Laboratory, Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, South Korea.
authors.forename: Chang Su
authors.initials: CS
authors.lastname: Jun
authors.forename: Byoung Yoon
authors.initials: BY
authors.lastname: Kim
authors.forename: Ju Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Eun Seong
authors.initials: ES
authors.lastname: Lee
authors.forename: Dong-Il
authors.initials: DI
authors.lastname: Yeom
mesh_terms: D007368:Interferometry; D009716:Numerical Analysis, Computer-Assisted; D055100:Optical Fibers; D013059:Spectrum Analysis, Raman; D041623:Tomography, Optical Coherence