Wei-Ping Huang

The perfectly matched layer (PML) boundary condition for the beam propagation method

The perfectly matched layer (PML) boundary condition for the Helmoltz equation is developed and applied to the finite-difference beam propagation method. Its effectiveness is verified by way of examples.

The perfectly matched layer boundary condition for modal analysis of optical waveguides: leaky mode calculations

The perfectly matched layer (PML) boundary condition is applied to modal analysis for optical waveguides. It is demonstrated that the PML is suitable and effective in computation of leaky modes.

Polarization rotation in semiconductor bending waveguides: a coupled-mode theory formulation

A theoretical model for the bending waveguide polarization rotator has been developed based on the full-vectorial wave equations and the coupled-mode theory. Calculation results from this model are found to agree favorably with measurement data reported in literature. It is found that the polarization conversion efficiency of this device hinges on the degree of asymmetry of the cross-sectional field profile with respect to both the x- and y-axes. Sensitivity analysis, furthermore, revealed that the device characteristics are strongly dependent on the waveguide geometry, in particular, the sidewall tilt angle and the amount of over-etch of the ridge waveguide. Finally, it is also found that the bending waveguide polarization rotator is virtually wavelength independent, making it suitable for wavelength division multiplexing (WDM) applications.

Full-vectorial wave propagation in semiconductor optical bending waveguides and equivalent straight waveguide approximations

Device characteristics of optical polarization rotators are founded upon the vector properties of the Maxwell equations. Recently, a bending waveguide based polarization rotator has been proposed and demonstrated. To provide a rigorous basis for the analysis and design of this polarization rotator, the full-vectorial wave equations for both E/spl I.oarr/ and H/spl I.oarr/-field in bending waveguides are derived. It is found from these wave equations that under a broad range of circumstances, a bending waveguide can be analyzed using the equivalent straight waveguide approximation. Details of the model for optical polarization rotators, which is based on the coupled-mode theory, will be described in a companion paper.

Full-vectorial mode analysis with considerations of field singularities at corners of optical waveguides

When electric field diverges at corners of optical waveguides, conventional numerical techniques such as the finite-difference method cannot be used for discretization of the wave equations. We have developed an algorithm for modal analysis such that singularity points at corner regions are handled properly. Calculation results are also shown to illustrate the effectiveness of this method.

Modeling and design of bending waveguide based semiconductor polarization rotators

A theoretical model for bending waveguide based semiconductor polarization rotators has been established, which is based on the full-vectorial wave equations for bending waveguides and coupled-mode theory. Calculation results obtained using this model and measurement data are found to be in good agreement.

Precision enhancement for optical waveguide analysis

The analytical form of the discretization error in modal calculations using the finite-difference method (in both one and two dimensions) has been derived. Based upon this knowledge, a linear extrapolation scheme is devised such that highly accurate propagation constants can be extracted from calculation results using coarse grids. Efficiency and precision are both improved significantly as a result.

Non-iterative Finite-Difference Scheme for Modal Calculations

The usual procedure of numerical modal calculations using finite-difference is to first discretize the Helmholtz equation