Transmission Line Matrix-integral Equation Research Articles

Modal and numerical analysis of the transverse magnetic-passing property of laminated cladding

An accurate investigation of an integrated optical polariser has been presented. The transverse magnetic (TM)-passing property for an asymmetrical slab with anisotropic cladding that behaves as negative or positive uniaxial crystal has been evaluated. After a modal analysis, the polarisation of the electromagnetic (EM) field is evaluated by means of transmission line matrix-integral equation (TLMIE) method which performs a 3D full-wave modelling of the structure (i) including dielectric losses and (ii) for different slant angle of the laminated cladding. The TLMIE method permits to maximise the TM-passing property for a single-mode channel with anisotropic cladding.

Analysis of an optical polarizer based on laminated-cover waveguide

A new simple form of a rib-waveguide polarizer is proposed and investigated. The cladding consists of a dielectric multilayer based on Si and SiO2; the core is a single-mode MO (magnetooptic) channel waveguide in Ce-substituted Yttrium Iron Garnet (YIG). The TM-passing property of the anisotropic cover filters out the unwanted polarization. The authors first develop a modal analysis of the rib waveguide and then perform a full-wave modeling of the polarizer by means of the transmission-line matrix integral equation (TLMIE) method. The TLMIE is an efficient three-dimensional (3-D) hybrid technique that combines the advantages of the numerical transmission-line matrix (TLM) method in dense finite regions, and those of the analytical Green's functions where available. The TLMIE method validates the modal analysis, yields an accurate physical insight of the polarization selection, and, it provides a tool for the optimization of the device

Efficient modeling of 3-D photonic crystals for integrated optical devices

We propose a full-wave numerical model of a three-dimensional (3-D) photonic crystal with the absolute photonic bandgap (PBG) centered at /spl lambda//spl sim/1.6 /spl mu/m. The analyzed structure is widely used in integrated optical circuitry. The electromagnetic analysis is performed by using the finite-element method (FEM) and transmission line matrix-integral equation (TLMIE) method. We analyze the reflection properties and compare theoretical results to experimental data. Due to its exact boundary conditions, TLMIE shows much higher accuracy with respect to FEM in the PBG optical band. As a demonstration, we have realized and analyzed a holographic polymer dispersed liquid crystal grating.

Accurate modeling of TE/TM propagation and losses of integrated optical polarizer

Photonic devices based on stacked multilayer waveguides are widely used in optical integrated architectures like polarizers, filters, photodetectors, laser, transducers for sensing applications, and microelectromechanical systems. In this paper, we present an accurate modeling of a waveguide polarizer based on an antiresonant reflecting optical waveguide (ARROW) structure utilizing birefringence form. The ARROW polarizer is the case of a structure with severe "aspect-ratio" that most of numerical technique cannot handle. The electromagnetic analysis is performed by means of a transmission-line matrix integral-equation (TLMIE) method-based solver. TLMIE is a three-dimensional full-wave hybrid technique that combines the advantages of the numerical transmission-line matrix method in dense finite regions and those of the integral-equation method in homogeneous regions where analytical and/or numerical Green's functions are available. An accurate investigation of propagation/radiation properties of TE/TM modes is performed. Theoretical results of TE/TM losses are compared to measured data showing very good agreement. Starting from this validation, it seems possible to provide design criteria for the optimization of the polarizer.

Accurate analysis and modeling of laminated multilayered 3-D optical waveguides

The theoretical investigation of waveguides having nonuniform cross-sections is an attractive and challenging problem which deserves serious interest. In this paper, we present a novel analysis of laminated multilayered three-dimensional waveguide, based on two modes: 1) a new coupled transmission line approach that considers the sloping of the layers along the longitudinal direction and 2) a transmission line matrix integral equation (TLMIE) modeling that complete and extends the investigation of the field propagation. In method 1), we neglect radiation modes and their EM coupling. All physical effects instead are accounted for by the full-wave TLMIE method. By using TLMIE, we validate the EM analysis and calculate TE/TM losses, arising from radiation modes.

Full-Wave Analysis of Photonic Bandgap Integrated Optical Components by the TLM-IE Method

This paper presents the full-wave analysis of commonly encountered optical periodic structures by the novel transmission-line matrix/integral equation (TLM-IE) method. The TLM-IE is a three-dimensional full-wave hybrid technique that combines the advantages of the numerical TLM method in dense finite regions and those of the IE method in open regions where simple Green functions are available. The pre- and postprocessing tools of the TLM-IE solver provide visualization and physical insight into the dynamics of electromagnetic propagation in such devices. The aim of this effort is twofold: 1) to analyze the diffraction and reflection characteristics of photonic bandgap gratings and 2) to define optimization guidelines for the Q factor of integrated dielectric resonators.

Accurate analysis of H-shaped antenna coupled to microstrip feed-line

An accurate investigation of a microstrip H-shaped antenna is presented, coupled by means of an aperture or via-hole to a microstrip feed-line. The EM analysis is performed by means of the hybrid transmission line matrix-integral equation method. The calculated S-parameters are compared to measured results and to those obtained by the generalised transverse resonance-diffraction method.

Accurate modeling of metal plate-loaded loop-coupled cavities with slots

In this work, we analyze the problem of the electromagnetic field radiated from apertures in coaxial fed metal enclosures loaded with metal inserts. Such situations are found, for example, in PC environments where slots and apertures are used for the purpose of heat dissipation, CD-ROMs, cable penetration etc. We derive an accurate model of the entire structure, including the coaxial line-to-loop-to-cavity feed and the inner metal planes, simulating the presence of the circuitry inside. The analysis is developed by means of the hybrid transmission line matrix-integral equation (TLM-IE) method and theoretical results are compared with experimental ones showing very good agreement. The evaluation of the reflection coefficient and of the level of radiated emission as functions of the metal plates position is very helpful toward the engineering design of the entire structure. The numerical simulations require rather low computational effort.

Efficient analysis and modelling of the radiation of microstrip lines and patch antennas by the TLM-integral equation (TLM-IE) method

A rigorous analysis of printed circuits and antennas requires a great computational effort, due to the necessity of an accurate modelling of large metallic structures, including radiating patches and feeding lines. The computational effort increases if we have to deal with radiation phenomena in large free space regions. In this contribution we present an accurate and efficient modelling of the electromagnetic field radiated by a microstrip line and by a patch antenna. The electromagnetic analysis is performed using a hybrid method, the Transmission Line Matrix-Integral Equation (TLM-IE) method. This method combines the advantages of the Transmission Line Matrix (TLM) method and the Integral Equation (IE) method, i.e. the high flexibility of the TLM method with respect to arbitrary object shapes and the effectivity of the IE method in analysing large homogeneous regions. Copyright © 1999 John Wiley & Sons, Ltd.