A drastic change from a transparent smectic-A (SmA) phase to a light-scattering chiral nematic (N*) one is achieved in [side chain smectic-A liquid crystalline polymer (SCSmALCP)/low molecular weight nematic liquid crystal (LMWNLC/chiral dopant] a ternary composite system with a homeotropic boundary condition. The light-scattering state of the induced N* phase can be resumed into the initially transparent SmA phase on cooling slowly, and be frozen in the SmA phase on cooling rapidly. The effects of the composition of the ternary composite system on such thermo-optical characteristics are investigated.