Finite Element Analysis of Optical Waveguide Discontinuity Problem

Purpose

Transmission properties of optical waveguide devices are analyzed in frequency domain (Continuous wave with a given wavelength is assumed as an incident wave).

Overview

As shown in the follwing figure, first, computational domain including waveguide device to be solved is discretized using triangular element (or tetrahedral element for 3D analysis), then the field distribution in each element is assumed to be expressed by simple polynomial function. The unknown field amplitudes are determined by minimizing the functional corresponding to the differential equation to be solved. The left figure shows the waveguide geometry, the center figure shows the finite element mesh, and the right figure shows the propagating optical field in frequency domain.

Considering time harmonic term, the time domain propagation behavior can be shown as an animation as following figure.

Numerical Example

Three dimensinal Y-branching waveguide

Inputted light is equally divided and transmits into two output ports. The following figure shows the propagating field in Y-branching waveguide.