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Indexed by:Journal Papers

Date of Publication:2020-01-01

Journal:PROCEEDINGS OF THE ESTONIAN ACADEMY OF SCIENCES

Included Journals:EI、SCIE

Volume:69

Issue:1

Page Number:74-80

ISSN No.:1736-6046

Key Words:Fabry-Perot resonator; dual secondary coherent light source array model; fundamental mode; phase difference; diffraction efficiency

Abstract:To study the mechanism of periodic change of reflective rectangular metallic gratings' diffraction efficiencies, a dual secondary coherent light source array model was established based on the theory of Fabry-Perot resonator. It was assumed that when incident light falls on the grating surface, it transforms into two coherent sources on each grating period. One is on the upper surface of the grating, reflected by the metal surface; the other is at the entrance of the grating groove and propagates in the form of a fundamental mode (lambda(f)). Based on the above mentioned hypothesis, formulae for the phase difference Delta phi of two sources and diffraction efficiency for the first and zero order with grating height h, were established. Delta phi and h are linear relationships, the phase difference Delta phi change due to the change of grating height h is the essencial cause of periodic changes of the diffraction efficiencies. When Delta phi has a certain value, the energy is distributed only in the zero or the first order direction. The model does not only show the change regularity of each diffraction order's diffraction efficiency of reflective rectangular metallic grating, but it also shows the correlation of each diffraction order. It can help to predict diffraction performance of rectangular metallic gratings and to design gratings.