Vibration-selective coherent anti-Stokes Raman scattering with linearly chirped white-light pulses

A practical extension of selective excitation using broadband laser is reported. A specific molecular vibration is excited by stimulated Raman scattering induced by a pair of linearly chirped white-light pulses (650-900 nm). The white-light pulse is generated by filamentation produced in a focused Ti:sapphire laser beam (∼30 fs, 1.8 mJ/pulse). The excited amplitude is probed by coherent anti-Stokes Raman scattering using the third pulse with a narrow bandwidth (769.9 ± 1.5 nm). As a demonstration, the N2 and O2 molecules are respectively excited at different time intervals of the pulse pair without changing the wavelength region of the light source.

LCPS-CARS scheme with a white-light pulse as the identical source of pump and Stokes pulses.129