Theory of Many Wannier Excitons. II. Absence of Self-Induced Transparency

The present paper has the dual purposes. As the first purpose, it is demonstrated that the boson description of Wannier excitons introduced in the preceding paper is suitable also to discussion of non-linear coherent interaction of Wannier excitons with the radiation field. The second purpose is to discuss the possibility of self-induced transparency due to Wannier excitons on the basis of the boson description by making clear the difference between a two-level atomic system and a system of excitons which can propagate in a crystal as polariton. As a result, stable pulse propagation of the radiation field is shown to be prevented by the polariton effect of excitons.