Selective excitation of femtosecond coherent anti-Stokes Raman scatteringin the mixture by phase-modulated pump and probe pulses

摘要

In this paper, we present a feasible method to realize and improve the selective excitation offemtosecond coherent anti-Stokes Raman scattering (CARS) in a mixture. We theoretically showthat, by shaping both the pump and probe pulses with the 7r phase step, the CARS signal from onequantum system can be enhanced and simultaneously that from the other quantum system iseffectively suppressed. Comparing with only shaping the probe pulse [D. Oron, N. Dudovich,D. Yelin, and Y. Silberberg, Phys. Rev. Lett., 88, 063004 (2002)], the selectivity of femtosecondCARS by shaping both pump and probe pulses can be greatly improved. Finally, we experimentallycompare two shaping schemes by investigating the selective excitation of the femtosecond CARS inthe mixture of dibromomethane (CH_2Br_2) and chloroform (CHCl_3).