Flexible dual-soliton manipulation for coherent anti-Stokes Raman scattering spectroscopy

Though dual soliton is used as the Stokes source in coherent anti-Stokes Raman scattering (CARS) experiments, the mechanism behind it is still not fully investigated. In this paper, dual-soliton pulses generation with a highly birefringent photonic crystal fiber (PCF) is numerically explored and experimentally verified. The simulated pulse exhibits various characteristics in the temporal and spectral domains with respect to the input linear polarization angle, and can be classified into four regions based on distances in the temporal and spectral domain of the soliton pair. By tuning input power and polarization angle, a soliton pair with desirable spectral coverage and temporal delay for CARS applications can be flexibly generated before the two solitons overlap in time domain. The simulated results are then experimentally validated by comparing their temporal and spectral characteristics. In addition, the benefit of using dual-soliton sources, such as Stokes beam, in CARS experiments is also demonstrated. The results and methods presented in this work can improve CARS spectroscopy and microscopy techniques, and may also be beneficial to other dual-wavelength source applications.