Theoretical and experimental studies of light diffraction anisotropy by holograms in a-As-S-Se films

摘要

Diffraction anisotropy (DA) defined as the polarization dependence of the amplitudes (amplitude DA) and phases (phase DA) of the diffracted light waves is studied in the case of a sinusoidal transmission amplitude-phase grating both theoretically and experimentally. Theoretical analysis was mainly based on the Kogelnik's coupled wave theory (KCWT) and also on the conclusions of rigorous coupled wave theory (RCWT) and effective medium theory (EMT). Experimentally gratings with 0.42 μm period in a-As-S-Se films at 632.8 nm were studied. KCWT predictions were compared with those of RCWT and EMT as well as with the experimental DA results. It is found that KCWT properly describes the first order amplitude DA, and more roughly also the zeroth order amplitude DA. The zeroth order phase DA is wrongly described by KCWT. It is also found that polarization dependent Fresnel reflection effect is much stronger than DA therefore p-polarized hologram recording is preferable.