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.
© 2010 Optical Society of America
Original Manuscript: March 29, 2010
Revised Manuscript: June 10, 2010
Manuscript Accepted: June 14, 2010
Published: July 6, 2010
Vol. 5, Iss. 11 Virtual Journal for Biomedical Optics
Chang Su Jun, Byoung Yoon Kim, Ju Hyun Park, Jae Yong Lee, Eun Seong Lee, and Dong-Il Yeom, "Investigation of a four-wave mixing signal generated in fiber-delivered CARS microscopy," Appl. Opt. 49, 3916-3921 (2010)