  We consider a system of nonlinear Schr\"{o}dinger equations related to the
Raman amplification in a plasma. We study the orbital stability and instability
of standing waves bifurcating from the semi-trivial standing wave of the
system. The stability and instability of the semi-trivial standing wave at the
bifurcation point are also studied. Moreover, we determine the set of the
ground states completely.
