Applications of metamaterials in optical waveguide isolator

Abstract

Optical waveguide isolators are vital integrated optic modules in advanced optical fiber communication systems. This study demonstrates an integrated optical isolator which has simple structure consisting of three layers. The thin magnetic garnet film is sandwiched between linear dielectric cover and metamaterial (MTM) substrate. The effective refractive indexes for both forward and backward fields are analytically calculated by deriving the dispersion equation of the TM fields. The difference Δβ between the phase constant for forward and backward propagation is calculated numerically for different values of MTMs permittivity (ε_s) and permeability (μ_s). In all the calculations, the value of ε_sμ_s is kept equal to 4. Δβ is also plotted as a function of the film thickness. Results show that the value of Δβ changes with the parameters of MTMs and the film thickness. This helps in selecting the optimal design for the isolator at which Δβ approaches zero. The results are encouraging to propose an optical isolator.