A three-beam femtosecond
stimulated Raman scattering (SRS) scheme
is formulated and demonstrated to simultaneously induce two different
SRS processes associated with Raman-active modes in the same molecule.
Two SR gains involving a common pump pulse are coupled and compete:
As one of the Stokes beam intensities increases, the other SRS is
selectively suppressed. We provide theoretical description and experimental
evidence that the selective suppression behavior is due to the limited
number of pump photons used for both of the two SRS processes when
an intense depletion beam induces one SRS process. The maximum suppression
efficiency was ∼60% with our experimental setup, where the
SR gain of the ring breathing mode of benzene is the target SRS signal,
which is allowed to compete with another SRS process, induced by an
intense depletion beam, of the CH stretching mode. We anticipate a
potential of this new switching-off concept in super-resolution label-free
microscopy
