Principles Of Terahertz Time Domain Spectroscopy

Terahertz time-domain spectroscopy (THz-TDS) is a unique technique for characterizing the response of materials and devices in the far-infrared region of the electromagnetic spectrum. Based on the measurement of transmitted or reflected ultra-short electromagnetic pulses and on a Fourier-transform of the recorded waveforms, THz-TDS permits fast and precise determination of the permittivity or permeability of materials over a wide bandwidth. This book is devoted to the determination of this spectral response of samples from the recorded waveforms.

The development of new sources and methods in the terahertz spectral range has generated intense interest in terahertz spectroscopy and its application in an array of fields. Presenting state-of-the-art terahertz spectroscopic techniques, Terahertz Spectroscopy: Principles and Applications focuses on time-domain methods based on femtosecond laser sources and important recent applications in physics, materials science, chemistry, and biomedicine. The first section of the book examines instrumentation and methods for terahertz spectroscopy. It provides a comprehensive treatment of time-domain terahertz spectroscopic measurements, including methods for the generation and detection of terahertz radiation, methods for determining optical constants from time-domain measurements, and the use of femtosecond time-resolved techniques. The last two sections explore a variety of applications of terahertz spectroscopy in physics, materials science, chemistry, and biomedicine. With chapters contributed by leading experts in academia, industry, and research, this volume thoroughly discusses methods and applications, setting it apart from other recent books in this emerging terahertz field.

Terahertz time-domain spectroscopy (THz-TDS) is a unique technique for characterizing the response of materials and devices in the far-infrared region of the electromagnetic spectrum. Based on the measurement of transmitted or reflected ultra-short electromagnetic pulses and on a Fourier-transform of the recorded waveforms, THz-TDS permits fast and precise determination of the permittivity or permeability of materials over a wide bandwidth. This book is devoted to the determination of this spectral response of samples from the recorded waveforms.

This book covers the latest advances in the techniques employed to manage the THz radiation and its potential uses. It has been subdivided in three sections: THz Detectors, THz Sources, Systems and Applications. These three sections will allow the reader to be introduced in a logical way to the physics problems of sensing and generation of the terahertz radiation, the implementation of these devices into systems including other components and finally the exploitation of the equipment for real applications in some different field. All of the sections and chapters can be individually addressed in order to deepen the understanding of a single topic without the need to read the whole book. The THz Detectors section will address the latest developments in detection devices based on three different physical principles: photodetection, thermal power detection, rectification. The THz Sources section will describe three completely different generation methods, operating in three separate scales: quantum cascade lasers, free electron lasers and non-linear optical generation. The Systems and Applications section will take care of introducing many of the aspects needed to move from a device to an equipment perspective: control of terahertz radiation, its use in imaging or in spectroscopy, potential uses in security, and will address also safety issues. The text book is at a level appropriate to graduate level courses up to researchers in the field who require a reference book covering all aspects of terahertz technology.

Terahertz (THz) technology is an active area of research, but only in recent years has the application of THz waves (T waves) in food and agricultural industries been explored. Terahertz Technology: Principles and Applications in the Agri-Food Industry describes the operating principles of THz technology and discusses applications and advantages of the THz regime of the electromagnetic spectrum for use in the agri-food industry. The agri-food industry is focusing on the development of non-destructive quality evaluation techniques that can provide accurate analysis quickly and are environmentally friendly. Among such techniques is THz technology that provides a novel noninvasive approach to quality assessment and safety assurance of agri-food products. The low energy of T waves is best suited for the analysis of sensitive biomaterials and does not cause photoionization. Therefore, THz imaging is complementary to X-ray imaging. Although accessing the THz spectrum is tedious by conventional devices, the combination of optics and electronics principles has opened a dimension of research in this field. This book provides an overview of THz spectroscopy and imaging, system components, types of THz systems, and applications and advantages of THz for applications in the agri-food industry. It describes the basic working mechanism, operating principle, operation modes, and system components of THz spectroscopy and imaging. Various advancements in THz technology related to agricultural and food applications are discussed that could serve as a guidebook for all those working and interested in non-destructive food assessment techniques. Key Features: Explores broader applications of the THz regime in the agri-food sector Describes system components, different forms of THz systems, and the working principle of T waves for spectroscopic and imaging techniques Provides insights on future research needs for industrial implementation of THz technology Complements the knowledge of other existing non-destructive spectroscopy and imaging techniques for food analysis Although books on biomedical applications of THz have been published, no book is available that deals with applications in the agri-food industry. Hence, Terahertz Technology is beneficial for undergraduate and graduate students and those food industry professionals involved in research related to non-destructive quality assessment and imaging techniques.

The terahertz regime of the electromagnetic spectrum was largely unexplored due to the lack of technology needed to generate and detect the radiation. However, in the last couple of decades, there has been a dramatic increase in tools needed to harness the radiation. This remarkable progress made in the development of terahertz sources, components, and detectors has resulted in an ever-increasing inquisitiveness of the applications of terahertz technology in a wide range of fields including medicine, pharmaceuticals, security, sensing, and quality assurance. This book, Terahertz Spectroscopy - A Cutting Edge Technology, presents an overview of the recent advances in terahertz technology and their application in a vast array of fields. The scientists and students are encouraged to read and share the content of this volume. The book also provides a good starting point for researchers who are new to the terahertz regime. The various chapters of the book have been written by renowned scientists in different parts of the world who are at the forefront of terahertz research fields. It is our (InTech publisher, editor, and authors) hope that this book will enhance knowledge and stimulate more interest and future research in terahertz technology.

The recent development of easy-to-use sources and detectors of terahertz radiation has enabled growth in applications of terahertz (Thz) imaging and sensing. This vastly adaptable technology offers great potential across a wide range of areas, and the Handbook of terahertz technology for imaging, sensing and communications explores the fundamental principles, important developments and key applications emerging in this exciting field. Part one provides an authoritative introduction to the fundamentals of terahertz technology for imaging, sensing and communications. The generation, detection and emission of waves are discussed alongside fundamental aspects of surface plasmon polaritons, terahertz near-field imaging and sensing, room temperature terahertz detectors and terahertz wireless communications. Part two goes on to discuss recent progress and such novel techniques in terahertz technology as terahertz bio-sensing, array imagers, and resonant field enhancement of terahertz waves. Fiber-coupled time-domain spectroscopy systems (THz-TDS), terahertz photomixer systems, terahertz nanotechnology, frequency metrology and semiconductor material development for terahertz applications are all reviewed. Finally, applications of terahertz technology are explored in part three, including applications in tomographic imaging and material spectroscopy, art conservation, and the aerospace, wood products, semiconductor and pharmaceutical industries. With its distinguished editor and international team of expert contributors, the Handbook of terahertz technology for imaging, sensing and communications is an authoritative guide to the field for laser engineers, manufacturers of sensing devices and imaging equipment, security companies, the military, professionals working in process monitoring, and academics interested in this field. Examines techniques for the generation and detection of terahertz waves Discusses material development for terahertz applications Explores applications in tomographic imaging, art conservation and the pharmaceutical and aerospace industries

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