Theory of complementary holograms arising from electron–hole transport in photorefractive media
The time evolution of space-charge field gratings in photorefractive media is derived for a simple two-level electron–hole-transport model. At one level, charge transfer occurs by electron transport, and at the other, by hole transport, thus leading to the formation of complementary gratings. If the characteristic lifetimes of the gratings differ significantly, extended-lifetime gratings are possible. The role of the applied electric field in the evolution of such gratings is examined, and limiting cases are considered. The results of the derivation are compared with examples of complementary gratings in the literature.
This study investigates the hydrodynamic performance of a submerged two layer horizontal plate breakwater. The plate thickness is considered as non-zero in the study. In the context of linear potential theory, an analytical solution for interaction of water waves with the plates is obtained using the matched eigenfunction expansion method. The solution consists of a symmetric part and an antisymmetric part. Its validity is confirmed by comparing the numerical results of reflection and transmission coefficients for limiting cases with previous predictions. Numerical examples are given to examine the major factors that affect the reflection and transmission coefficients of the plates. Some useful results are presented for engineering design.