  We demonstrate an approach for background-free three-dimensional imaging of
director fields in liquid crystals using stimulated Raman scattering
microscopy. This imaging technique is implemented using a single femtosecond
pulsed laser and a photonic crystal fiber, providing Stokes and pump
frequencies needed to access Raman shifts of different chemical bonds of
molecules and allowing for chemically selective and broadband imaging of both
pristine liquid crystals and composite materials. Using examples of model
three-dimensional structures of director fields, we show that the described
technique is a powerful tool for mapping of long-range molecular orientation
patterns in soft matter via polarized chemical-selective imaging.
