Design and Analysis of Laser to Fibre Coupling System Using Holographic Optical Element

Abstract

This paper focuses on design of cost effective, light – weight holographic coupler to couple laser light to optical fibre with reasonably appreciable diffraction efficiency. Optimization of  film thickness , index modulation depth  and fringe spacing  have been made to design holographic optical element recorded in high resolution silver halide film  for achieving  maximum coupling efficiency for Laser-to-Fiber coupling systems within specific optical windows. A theoretical investigation has been conducted under the light of coupled wave theory-based formula to analyze the variation in diffraction efficiency with wavelength for different values of ‘ ’,   and  . Theoretical analysis revealed that for on-Brag illumination, diffraction efficiency of recorded hologram does not changes significantly with change in fringe spacing hence optimization of  thickness (d) and refractive index modulation depth (  ) for a fixed fringe spacing to achieve peak efficiency for transmission window  and . was made. The results on optimization of parameter ‘ ’ and  to achieve a single laser to fibre coupler for the two optical windows  and , operating at  and 1  respectively are presented. The paper also discusses the advantages on use of Holographic Optical Elements (HOEs), such as lightweight, thin-film geometry, cost-effectiveness, and ease of fabrication. The paper also emphasizes on role of use of HOEs in technological advancement of optical communication for real world application.