PREFACE

Electromagnetic simulation is an established tool across many scientific and technological disciplines, buoyed by the development of high-power computer platforms. This holds true in the field of photonics, where recent years have seen major advances in theoretical, numerical, and computational techniques. These advances have been driven by the emergence of sophisticated integrated photonic systems, on the one hand, and sub-wavelength device structuring to enhance light– matter interactions on the other, all aimed towards the generation, transmission, localisation, manipulation, detection, and use of light. The annual Optical Wave and Waveguide Theory and Numerical Modelling (OWTNM) Workshop has, since 1992, provided a forum for lively debates, intended to bring forward new ideas in the field of theoretical and computational photonics. This book brings together some of the cutting-edge work on computational methods in photonics presented at recent OWTNM meetings and addresses the physical understanding, mathematical description, and the computational treatment of guided optical waves, and related optical effects in microand nanostructures, including multi-physics effects. The first section of this book describes some numerical methodologies for computational photonics. Chapter 1 discusses the development of a finite-elementbased time-domain approach; the use of a perforated mesh increases numerical efficiency, which is compared against the well-established finite-difference time-domain (FDTD) method. Mid-infrared light sources have been intensively investigated in recent years since they can enable many applications, for example in remote sensing and medicine. Chapter 2 describes numerical investigations of some of the possibilities for obtaining mid-infrared laser action in rare earth-doped chalcogenide glass fibres, starting from some basic laser physics and progressing through the development of powerful numerical fibre laser models and the experimental techniques used to extract the model parameters. Chapter 3 then describes a hybrid analytical–numerical approach to coupled mode theory which leads to quantitative, computationally efficient and readily interpretable models for photonic integrated circuits. The application of these models is illustrated for components such as single and parallel waveguides, waveguide crossings, micro-resonators with