Waveguide CARS spectra of 4,4'-dibromobiphenyl dispersed in a polymethylmethacrylate optical waveguide

With the use of a waveguide geometry, CARS spectroscopy is found to be an extremely sensitive technique to detect a very low concentration of molecules dispersed in a matrix. Using a planar optical waveguide geometry, the CARS spectra of 4,4'-dibromobiphenyl dispersed in a ≈3 μm thick polymethylmethacrylate polymer film cast on a quartz substrate has been recorded using picosecond optical pulses. Different vibrational bands have been recorded using the TE₀ waveguide mode for both the pump and the probe pulses.