This book focuses on photoswitches. The objective of the book is to introduce researchers and graduate course students who are interested in "photon-working switches" not only to the fundamentals but also to the latest research being carried out in this field. Light can reach a target substrate without any physical contact to deliver energy. The energy can induce changes in the structure of the molecules included in the substrate so that its properties and functions are made switchable by light irradiation. When a substrate is able to revert to its original state, this system can be regarded as a "photon-working switch". The terms "photon-working switches" or "photoswitches" are almost equivalent in meaning to "photochromism"; however, they focus on the "switching of functions" of chemical species rather than their "reversible transformation". Most of the authors of this volume are members of PHENICS, an international research group on organic molecular photoswitches composed of research institutions from France, Japan, Russia, China and Germany. Since its inception in 2008, PHENICS has promoted active research to develop the field. This book commemorates the group's eighth year of collaborative research.

A comprehensive review to the synthesis, properties, and applications of diarylethene-based molecular photoswitches Diarylethene Molecular Photoswitches: Concept and Functionalities provides the fundamental concepts of molecular photoswitches and includes information on how the bistable photoswitches of diarylethenes modulate the functions of materials and biological activities. Written by Masahiro Irie (the inventor of photochromic diarylethene compound), the book explores the reaction mechanism, photoswitching performance, photoswitchable crystals, and the myriad applications of diarylethenes based photoswitches. This book offers academics, chemists, and engineers an essential resource for understanding the molecular photoswitches and provides a guide to the development of new photoresponsive materials. The author explores the applications based on diarylethene and its dirivatives to Field-Effect Transistors, Metal-Organic Frameworks including nanoparticles, super-resolution fluorescence microscopies, drug release, and self-healing materials. This important book: * Offers a guide to diarylethene derivatives, the most widely studied compounds worldwide among the photochromic compounds * Includes the basic concepts of molecular photoswitches * Explores the myraid applications grounded in diarylethene and its derivatives * Presents an authortative text from the inventor of the photochromic diarylethene compound Written for materials scientists, organic, polymer, and physical chemists, and electronics engineers, Diarylethene Molecular Photoswitches offers an introduction to the topic and includes recent developments in the field.

This book provides a comprehensive introduction to the theoretical and experimental studies of atomic optical bistability and multistability, and their dynamical properties in systems with two- and three-level inhomogeneously-broadened atoms inside an optical cavity. By making use of the modified linear absorption and dispersion, as well as the greatly enhanced nonlinearity in the three-level electromagnetically induced transparency system, the optical bistablity and efficient all-optical switching can be achieved at relatively low laser powers, which can be well controlled and manipulated. Until now, the rapid rate of progress in applications of multilevel systems in cross-disciplinary field has made it difficult to newcomers to the field to obtain a broad overview of this topic. This monograph will serve the purpose.

This book provides readers a good overview of some of most recent advances in the field of hybrid pixelated detectors for X-ray imaging. Coverage includes both technology and applications, with an in-depth review of the research topics conducted at leading research institutions in the world. The conversion of the X-ray signal into an analogue/digital value is discussed, as well as a review of CMOS chips used for X-ray image sensors. Applications of hybrid pixel detectors are discussed, such as medical imaging, high energy physics, space, non-destructive testing and security. Provides coverage of a broad range of topics, from international experts in academia and industry; Includes in-depth analysis of how to optimize X-ray detection and electronics for X-ray detection; Covers both technology and applications in a number of different domains.

In this chapter we review the process of parametric down-conversion (PDC) and discuss the different methods to use PDC as a heralded single-photon source. PDC is a non-linear optical process, where an incoming pump photon decays, under energy and momentum conservation, into a photon-pair. The creation of photons in pairs allows for the implementation of a single-photon source by detecting one photon (trigger) to herald the presence of its partner (signal). The engineering possibilities of PDC enable the generation of single-photons with high rates in a wide range of frequencies. This chapter is structured as follows: Section 11.2 describes the principles of PDC in non-linear media. We derive the quantum state of the generated photon-pairs, investigate the spectral purity and photon-number purity of the heralded signal photon and discuss the achievable single-photon generation rates. In section 11.3 we turn towards experimental realizations and introduce bulk crystal PDC. Section 11.4 elaborates on the use of periodic poling to engineer the PDC process. Finally, section 11.5 gives an overview over PDC in waveguides. A comparison of experimental data from various heralded singe-photon sources based on PDC is presented in section 11.6 with an overview of nonlinear materials suited for PDC given in section 11.7.

This book covers the technology of switching or modulating light in semiconductor optical waveguides. Currently a key function for optical communications systems is the conversion of data from an electrical signal to an optical signal for transmission in very low loss optical fibres and the converse process of optical to electrical conversion the O/E/O data conversion. This conversion between electronic and photonic signals imposes an energy consumption overhead on optical communication systems. So many research workers have been attracted to ultrafast all-optical switching of data in different formats. As a way of introduction to all-optical switching in semiconductor waveguides the book covers the electro-optic effect, electroabsorption and electrorefraction; effects that can be used in semiconductor optical modulation devices. But the book focuses on all-optical switching using second and third order optical nonlinearities in AlGaAs optical waveguides. It covers a variety of device configurations including integrated nonlinear couplers and Mach-Zehnder interferometers. Further, it provides design software in suit of Mathematica notebooks that can be used to explore the device design.

This chapter presents an overview of efforts to improve photon-counting detection systems through the use of hybrid detection techniques such as spatial- and time-multiplexing of conventional detectors, and frequency up-conversion. It reviews the basic operation for these methods and illustrates their utility in a number of applications showing new or improved capabilities compared with conventional methods.