Analysis of a Polarization Splitter With a Multilayer Filter Using a Pade-Operator-Based Power-Conserving Fourth-Order Accurate Beam-Propagation Method

A(1,1)Pade-operator-based fourth-order accurate finite-difference beam-propagation method is described for the analysis of the transverse-magnetic(TM)wave, with an emphasis on power conservation. As an application, a polarization splitter with a multilayer filter is analyzed. Reflectivities of more than 98% for the transverse-electric wave and transmissivities of more than 94% for the TM wave are obtained over a wide wavelength range of 1.1-1.65 μ

Antenna System Composed of T-Shaped Elements Coupled to an Open Radial Waveguide

An antenna system composed of an activated open radial waveguide (RadWG) and parasitic T-shaped elements is proposed as a high-gain antenna, where the radiation beam is steerable around the system axis. The T-shaped elements are proximity-coupled to the RadWG. It is found that the upper round plate for the RadWG contributes to forming a desirable beam and increasing the gain. The beam steering with a gain of greater than targeted 9 dBi in 16 azimuthal directions is obtained by changing the location of open-state T-shaped elements whose height is 0.18 wavelength. Effects on the radiation characteristics of the system parameters, including the RadWG height, upper round plate diameter, ground plane diameter, and number of open-state T-shaped elements, are also analyzed and discussed

A Three-Dimensional Multistep Horizontally Wide-Angle Beam-Propagation Method Based on the Generalized Douglas Scheme

A three-dimensional horizontally wide-angle beam-propagation method is formulated on the basis of the multistep method for higher order Pade approximants, together with the alternating-direction implicit scheme. The fourth-order accurate finite-difference formula is used to enhance the efficiency of the method. The effectiveness is demonstrated through the analyses of a tilted step-index waveguide and a multimode interference coupler

Semivectorial Mode Analysis of a Rib Waveguide by an Imaginary-Distance Beam-Propagation Method Based on the Generalized Douglas Scheme

The field profile and effective index of a rib waveguide are calculated using an improved semivectorial beam-propagation method using the imaginary-distance procedure. Convergence behavior of the effective index is compared with that obtained by the conventional Crank-Nicholson scheme and with that derived from a Bierwirth-type formula, demonstrating the effectiveness of the present method. Field discontinuities at the interface between different materials are clearly displayed

Leakage Loss and Phase Variation of a Buried Directional Coupler on a Silicon Substrate

Effects of the presence of a silicon substrate on the leakage loss and phase variation of silica-based parallel waveguides are investigated using the imaginary-distance beam-propagation method. The leakage loss is evaluated as a function of the distance between the core and the substrate. Calculation shows that the loss of the directional coupler can be estimated using the single waveguide with the same cross section. It is also found that the beat length becomes longer than that without the substrate except the case where the core is extremely close to the substrate. In terms of the loss reduction, the insertion of a SiO2. film with a 1-μm thickness corresponds to an increase in the distance between the core and the substrate without the SiO2. film by about 2μm