Phase matching in two-dimensional coherent Raman imaging

Coherent anti-Stokes Raman scattering (CARS) is a valuable spectroscopic tool for the measurement of temperature and species concentration. In recent years, multi-dimensional CARS has seen focused development and is especially important in reacting flows. An important aspect of multi-dimensional CARS is the phase-matching scheme used. Historically, collinear and BOXCARS phase-matching schemes have been used to achieve phase matching over a broad spectral range. For 1-D and 2-D CARS imaging, two-beam or counter-propagating beam arrangements are necessary. The two-beam arrangement offers many advantages, but introduces a phase mismatch which limits the spectral response of the measurement. This work explores the tradeoffs in spatial resolution, spectral bandwidth, and CARS intensity in 2-D CARS arrangements. Calculations are made for two-beam and counter-propagating beam CARS.