A robust, alignment-free broadband CARS system based on stimulated processes in heavy water

We have established a new method for realizing a typical “2-color” collinear CARS (coherent anti-Stokes Raman scattering) system. The system mainly consists of a laser source, a D2O cell, and a spectrometer. The pump/probe beam and the Stokes beam are provided by SBS (stimulated Brillouin scattering) and BSRS (backward stimulated Raman scattering) of D2O, respectively. The CARS system is statistically stable, and it is also a broadband and alignment-free system. Measurement of N2 signal in air with this system is demonstrated. Detection of N2 in 0.006 bar air is realized with this system. Time-resolved pulse shapes of SBS and BSRS are measured to confirm their generation. Transference of energy from the SBS pulse to the BSRS pulse is realized with a Rhodamine 101 dye cuvette and discussed. This results in a better energy distribution between the pump/probe and Stokes pulses for CARS.