Accurate modeling of photonic devices is essential for the development of new, higher performance optical components required by current and future high-bandwidth communications systems. This paper reviews several key techniques for such modeling, many of which are used in commercial design tools. These include several mode-solving techniques, the beam propagation method, the method of lines, and the finite-difference time-domain technique.

Numerical techniques for modeling guided-wave photonic devices

We describe a new full-vector finite difference discretization, based upon the transverse magnetic field components, for calculating the electromagnetic modes of optical waveguides with transverse, nondiagonal anisotropy. Unlike earlier finite difference approaches, our method allows for the material axes to be arbitrarily oriented, as long as one of the principal axes coincides with the direction of propagation. We demonstrate the capabilities of the method by computing the circularly-polarized modes of a magnetooptical waveguide and the modes of an off-axis poled anisotropic polymer waveguide.

http://www.photonics.umd.edu/wp-content/uploads/pubs/ja-20/Fallahkhair_JLT_26_1423_2008.pdf

Vector Finite Difference Modesolver for Anisotropic Dielectric Waveguides

Surface plasmon polaritons (SPPs) are electromagnetic (EM) modes propagating along metal‐dielectric interfaces, in which surface collective excitations of free electrons in the metal are coupled to evanescent EM fields in the dielectric. Various SPP modes can be supported by flat and curved, single and multiple surfaces, exhibiting remarkable properties, including the possibility of concentrating EM fields beyond the diffraction limit, i.e. on the nanoscale, while enhancing local field strengths by several orders of magnitude. This unique feature of SPP modes, along with the ever-increasing demands for miniaturization of photonic components and circuits, generates an exponentially growing interest in SPP-mediated radiation guiding and SPP-based waveguide components. Here we review the current status of this rapidly developing field, starting with a brief presentation of the main planar SPP modes along with the techniques employed for their excitation and manipulation by sets of nanoparticles. We then describe in detail various SPP-based waveguide configurations that ensure two-dimensional mode confinement in the plane perpendicular to the propagation direction and compare their characteristics. Excitation of SPP waveguide modes and recent progress in the development of SPP-based waveguide components are also discussed, concluding with our outlook on challenges and possible future developments in this field. (Some figures may appear in colour only in the online journal) This article was invited by Horst-Guenter Rubahn.

http://iopscience.iop.org/article/10.1088/0034-4885/76/1/016402/pdf

Radiation guiding with surface plasmon polaritons

Smart technology for textiles and clothing - an overview and review. Electrically active polymer materials: application of non-ionic polymer gel and elastomers for artificial muscles. Heat storage and thermo-regulated textiles and clothing. Thermally sensitive materials. Cross-linked polyol fibrous substrates as multifunctional and multi-use intelligent materials. Stimuli-responsive interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(acrylic acid. Permeation control through stimuli-responsive polymer membrane prepared by plasma and radiation grafting techniques. Mechanical properties of fibre Bragg gratings. Optical responses of FBG sensors under deformations. Smart textile composites integrated with fibre optic sensors. Hollow fibre membranes for gas separation. Embroidery and smart textiles. Adaptive and responsive textile structures (ARTS. Wearable technology for snow clothing. Bio-processing for smart textiles and clothing. Tailor-made intelligent polymers for biomedical applications. Textile scaffolds in tissue engineering.

Smart fibres, fabrics and clothing

This lecture presents the perfectly matched layer (PML) absorbing boundary condition (ABC) used to simulate free space when solving the Maxwell equations with such finite methods as the finite difference time domain (FDTD) method or the finite element method. The frequency domain and the time domain equations are derived for the different forms of PML media, namely the split PML, the CPML, the NPML, and the uniaxial PML, in the cases of PMLs matched to isotropic, anisotropic, and dispersive media. The implementation of the PML ABC in the FDTD method is presented in detail. Propagation and reflection of waves in the discretized FDTD space are derived and discussed, with a special emphasis on the problem of evanescent waves. The optimization of the PML ABC is addressed in two typical applications of the FDTD method: first, wave-structure interaction problems, and secondly, waveguide problems. Finally, a review of the literature on the application of the PML ABC to other numerical techniques of elec...

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Perfectly Matched Layer (PML) for Computational Electromagnetics

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 (PML) boundary condition for the beam propagation method

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.

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

An extension of the full-vectorial beam propagation method to anisotropic media is presented. Optical waveguides made of anisotropic materials can be modeled and simulated. The polarization dependence and coupling due to both the material and the geometric effects are considered. >

A full-vectorial beam propagation method for anisotropic waveguides

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

An unconditionally stable vectorial beam propagation method for three-dimensional structures is developed and presented. The stability criteria is theoretically proved, and verified numerically. Since this new algorithm conserves power it can be used to calculate the loss of optical guided-wave structures accurately. >

C.L. Xu

Papers

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

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

A full-vectorial beam propagation method for anisotropic waveguides

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

An unconditionally stable vectorial beam propagation method for 3-D structures