Research Of Diffraction And Polarization Properties Of Reflection Volume Holograms

The reflection volume hologram recorded in dichromated gelatin (DCG) is a kind of holographic optical element (HOE) which has non-uniform distribution in index modulation and fringe period. It has not only high diffraction efficiency and spectral selectivity, but also high polarization selectivity, and can be used as an optical element with multi-functions. In this paper, the diffraction and polarization properties of reflection volume holograms have been investigated theoretically and experimentally.In the first, several kinds of polarization beam-splitters (PBS) are introduced. The development in the research of holographic PBS and coupled wave theory are reviewed.Then, a vectorial wave equation is deduced from Maxwell's equation. And vectorial coupled wave equations is obtained, in which the non-uniformity of the medium has been considered. The models of non-uniform distribution in the medium are established as well.The diffraction efficiencies of s-polarization and p-polarization propagated in reflection volume holograms have been measured in detail. It is found that there exists "birefringence " in reflection HOEs. The average indexes of two orthogonal polarization components are reduced after DCG has been processed, and vary with the incident angles. By applying the vectorial coupled wave theory with non-uniform distribution models, the diffraction efficiencies of s-polarization and p-polarization, the average indexes of different incident angles are calculated theoretically. The results show that the theory is identical with the experiment results well. Then it is concluded that the vectorial coupled wave theory of non-uniform medium is reliable in practice.The characteristics of the reflection HOE used as a PBS have also been measured and the potential application of the HOE is discussed.Finally, the aspects for further research are presented.