Efficient simulation and analysis of quantum ballistic transport in nanodevices with AWE

Quantum-mechanical modeling of ballistic transport in nanodevices usually requires solving the Schrdinger equation at multiple energy points within an energy band. To speed up the simulation and analysis, the asymptotic waveform evaluation is introduced in this paper. Using this method, the wave function is only rigorously solved at several sampled energy points, whereas those at other energies are computed through Pad approximation. This allows us to obtain the physical quantities over the whole energy band with very little computational cost. In addition, the accuracy is controllable by a complex frequency hopping algorithm. The validity and efficiency of the proposed method are demonstrated by detailed study of several multigate silicon nano-MOSFETs. © 2006 IEEE.published_or_final_versio

Terahertz and Millimetric Rectennas

In recent years, the energy market has witnessed increasing demand on green electromagnetic energy resources to meet the next generation devices requirements. While energy harvesting in the lower gigahertz band has witnessed many improvements leading to market-ready solutions, the terahertz harvesting is, still, in an immature state. As will be demonstrated later, the electromagnetic radiation frequency identifies the theory of operation and so the rectifiers are categorised, into lower and upper frequency bands. While the theoretical framework for the lower frequency rectifiers is more "uniform", there are many theories to explain the rectifier operation for upper frequency bands. For the latter case, Simmons and the transfer matrix method models are chosen and elaborated in more details. An optimisation framework that deploys the transfer matrix method to calculate the voltage-current relationship of a tunnelling diode and improve the relevant figures of merit will be also suggested. New and novel techniques leading to optimized wireless energy transmission will be elaborated. In this context, the time-modulated array technique will be considered and studied, for a range of frequencies extending to 28 GHz, as a possible substitution to the lossy linear phased array control circuits. The novel frequency-diverse array technique, leading to distance-dependent radiation pattern behaviour, will be also discovered. A market-ready solution for an efficient 2.4 GHz energy-harvesting device is presented and tailored to work in harsh electromagnetic environments. Starting from a simple and generic rectifier model, the design is upgraded to reach an end-product prototype together with its measurements in a real-world scenario. In the end, an efficient and fast simulation method capable to calculate the received power by wireless sensors is also presented. Thanks to the integral solver simulation, the results are more accurate than typical finite difference simulation and are obtained much faster as demonstrated in the corresponding chapter

Modern Applications in Optics and Photonics: From Sensing and Analytics to Communication

Optics and photonics are among the key technologies of the 21st century, and offer potential for novel applications in areas such as sensing and spectroscopy, analytics, monitoring, biomedical imaging/diagnostics, and optical communication technology. The high degree of control over light fields, together with the capabilities of modern processing and integration technology, enables new optical measurement systems with enhanced functionality and sensitivity. They are attractive for a range of applications that were previously inaccessible. This Special Issue aims to provide an overview of some of the most advanced application areas in optics and photonics and indicate the broad potential for the future