  We show that, in multimode Raman lasers, cascaded light scattering (CLS) not
only extends the optical frequency range, but could also modulate the laser
dynamics. The origin of this phenomenon is based on the fact that many Raman
lasing modes are directly correlated through CLS. The coupled-mode equations
only describe single-mode cascaded Raman lasers and are insufficient for
describing the multimode case. In this work, we introduce additional terms to
account for intermodal interaction and, thence, reveal the physical mechanism
behind the mode-switching phenomenon. Additionally, mode-switching controlled
solely by a single-mode pump in whispering gallery mode (WGM) silica Raman
lasers is demonstrated. As the intracavity pump power is increased, laser
switching happens between two adjacent WGMs in the same mode family.
