Casimir Force Between Two Spatially Dispersive Dielectric Parallel Slabs

We investigate the Casimir force F between two parallel spatially dispersive semiconductor slabs, whose dielectric response function accounts for nonlocal effects. Nonlocal effects are induced by the presence of excitonic transitions in the semiconductor slabs for which our studies consider the A _n?=?1 exciton in CdS and the Z₃1s one in CuCl. In order to explore the nonlocal effects in the Casimir force, we first calculate the S and P polarized reflection coefficients of the excitonic slabs then we use them in the functional form of F. The slabs are considered as homogeneous, and nonhomogeneous media where the latter is a periodic system having a unit cell with period d. We present numerical calculations of F as a function of the vacuum gap of width L between the slabs, different slab thicknesses, and periods. Comparisons between numerical results obtained by using a nonlocal and a local theory show that the nonlocal effects are more significant at short separations of the slabs. F suffers a small decrease as a consequence of the energy absorption induced by the excitons.