Reflection and transmission characteristics of rectangular dielectric waveguide junction with transverse displacement

Abstract

AbstractIn the case where rectangular dielectric waveguides with identical cross sections and relative permittivity are connected with a lateral offset, the reflection and transmission coefficients of the guided mode in this portion are calculated and the radiation power is obtained. First, the boundary condition to be satisfied by the electromagnetic field in the junction plane (perpendicular to the direction of propagation) at the offset junction is determined. Next, a double Fourier transform is applied to this boundary condition and the latter is solved in the spectral domain. The reflection and transmission coefficients thus obtained are used as the first‐order approximation and the parameters corresponding to the phase constants introduced separately in the spectral domain are corrected successively. By means of this approach, the reflection and transmission coefficients of the guided mode can be converged to constant values. The reflection and transmission coefficients obtained in this manner are used for calculation of the radiated power generated at the offset discontinuity. It is confirmed that the energy conservation law holds almost at this offset junction. Hence, the numerical accuracy is believed sufficient. A portion of the results was compared with the experimental data and good agreement was found. The present analysis method is believed to be useful for such integrated circuit design as calculation of the allowable offset values in an optical communication system in which rectangular dielectric waveguides are connected with offset.