Microwave modelling of optical diffraction grating devices

Abstract

Design methods for obtaining shaped radiation patterns and beam control from optical diffraction gratings are presented, based on equivalent radiating currents and measurements of radiation leakage on the grating itself or microwave models, the latter offering many advantages as an initial design process prior to optical manufacture. Under certain assumptions the design method represents a unified process that is applicable to both linear and annular gratings. Microwave model measurements on copper strip linear and annular gratings substantiate the design methods and illustrate the polarisation properties enforced by the grating and substrate structure. Novel ideas concerning possible electronic beam scanning using linear gratings on electrooptic substrates and also the creation of eye-safe broad beams using random phase hologram gratings on optical D-fibres, are examined using the design methods.