Roles of surfaces in polariton dynamics

Abstract

We develop the additional boundary conditions in the particle picture for the film medium. Then polariton dynamics can be discussed taking into account the reflection effects at the front and rear surfaces. At normal incidence of laser light with frequency larger than the longitudinal exciton, upper-branch polaritons (with small wave number) are by a few orders of magnitude more densely excited than lower ones with large wave number. In the film medium, however, they are almost equalized because the latters are accumulated in the medium although the formers escape easily from both the surfaces. Second, lower-branch polaritons are reflected into lower or upper ones with opposite wave numbers in sign so that the correlation effect among them is induced. These are discussed quantitatively refering to the observations by Kuwata and Nagasawa.