2002/07/01 by D. K. Gramotnev, Dmitri K. Gramotnev, T. A. Nieminen +3
Engineering · Materials Science · Physics and Astronomy · #Optical Coatings and Gratings #Photonic Crystals and Applications #Photonic and Optical Devices #physics.optics
paper · pdf · doi:10.1080/09500340110109403
published as Journal of Modern Optics 49(9), 1567-1585 (2002) · 16 pages, 5 figures
openalex publication_date 2002/07/01 · arxiv created 2005/09/06 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Extremely asymmetrical scattering (EAS) is an unusual type of Bragg scattering in slanted periodic gratings with the scattered wave (the +1 diffracted order) propagating parallel to the grating boundaries. Here, a unique and strong sensitivity of EAS to small stepwise variations of mean structural parameters at the grating boundaries is predicted theoretically (by means of approximate and rigorous analyses) for bulk TE electromagnetic waves and slab optical modes of arbitrary polarization in holographic (for bulk waves) and corrugation (for slab modes) gratings. The predicted effects are explained using one of the main physical reasons for EAS—the diffractional divergence of the scattered wave (similar to divergence of a laser beam). The approximate method of analysis is based on this understanding of the role of the divergence of the scattered wave, while the rigorous analysis uses the enhanced T-matrix algorithm. The effect of small and large stepwise variations of the mean permittivity at the grating boundaries is analysed. Two distinctly different and unusual patterns of EAS are predicted in the cases of wide and narrow (compared to a critical width) gratings. Comparison between the approximate and rigorous theories is carried out.