This book is the result of the NATO Advanced Research Workshop on Frontiers in Planar Lightwave Circuit Technology, which took place in Ottawa, Canada from September 21-25, 2004. Many of the world’s leading experts in integrated photonic design, theory and experiment were invited to give lectures in their fields of expertise, and participate in discussions on current research and applications, as well as the new directions planar lightwave circuit technology is evolving towards. The sum of their contributions to this book constitutes an excellent record of many key issues and scientific problems in planar lightwave circuit research at the time of writing. In this volume the reader will find detailed overviews of experimental and theoretical work in high index contrast waveguide systems, micro-optical resonators, nonlinear optics, and advanced optical simulation methods, as well as articles describing emerging applications of integrated optics for medical and biological applications. vii Acknowledgements We would like to acknowledge and express our gratitude to the several organizations whose support and involvement made this NATO Advanced Research Workshop possible. This workshop was of course made possible because of the initial financial grant awarded by the NATO Security through Science Programme in Brussels, Belgium. We also acknowledge the Canadian Institute for Photonic Innovation (CIPI), the Canadian Photonics Fabrication Center and the National Research Council Canada, the Center for Research in Photonics at the University of Ottawa, Carleton University, Optiwave Systems Inc. and the Canadian Microelectronic Center for their generous support and/or cooperation.