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.

Principles of Terahertz Science and Technology aims to elucidate the fundamentals of THz technology and science for potential new users. It surveys major techniques of generating, detecting, and manipulating THz waves and also discusses a number of essential processes where THz waves interact with physical, chemical, and biological systems. This book serves as an introduction to THz technology for new researchers in various fields.

Many different disciplines, such as ultrafast spectroscopy, semiconductor device fabrication, bio-medical imaging and more, involve the recent development of THz technology. It is necessary to lay down a strong, common foundation among researchers, so that communication can proceed smoothly. Previous THz research activities have concentrated on generation and detection, but the focus has now shifted to practical applications of this technology, such as high-speed optoelectronic signal processing and molecular spectroscopy.

Drawing upon years of practical experience and using numerous examples and illustrative applications Yun-Shik Lee discusses:

The major techniques of generating, detecting, and manipulating THz waves
Essential processes where THz waves interact with physical, chemical, and biological systems
Medical Applications of T-Ray Imaging including, optical properties of human tissue, cancer diagnostics, reflective imaging of skin burns and detection of dental caries
Principles of Terahertz Science and Technology is an ideal book for applied physicists, microwave engineers, biomedical engineers, electrical engineers, and analytical chemists interested in the fundamentals and applications of THz engineering.

The inherent advantages and potential payoffs of the terahertz (THz) regime for military and security applications serve as an important driver for interest in new THz-related science and technology. In particular, the very rapid growth in more recent years is arguably most closely linked to the potential payoffs of THz sensing and imaging (THz-S&I).
This book presents some of the leading fundamental research efforts towards the realization of practical THz-S&I capabilities for military and security applications. Relevant subjects include theoretical prediction and/or measurement of THz spectroscopic phenomenon in solid-state materials such as high explosives (e.g. HMX, PETN, RDX, TNT, etc.), carbon-fiber composites, biological agents (e.g. DNA, RNA, proteins, amino acids) and organic-semiconductor nanostructures. Individual papers also address the effective utilization of state-of-the-art THz-frequency technology in military and security relevant scenarios such as standoff S&I, screening of packages and personnel, and perimeter defense. Technical papers introduce novel devices and/or concepts that enhance THz source and detector performance, enabling completely new types of sensor functionality at THz frequency (e.g. detection at nanoscale/molecular levels), and defining new and innovative sensing modalities (e.g. remote personnel identification) for defense and security. Therefore, the collective research presented here represents a valuable source of information on the evolving field of THz-S&I for military and security applications.

The book presents recent and important developments in the field of terahertz radiation with a particular focus on pulsed terahertz radiation. Situated in the gap between electronics and optics, the terahertz frequency range of the electro-magnetic spectrum has long been neglected by scientists and engineers due to a lack of efficient and affordable terahertz sources and detectors. The advent of femtosecond lasers in the 1980s and photoconductive switches in 1984 have made the terahertz gap accessible, while at the same time advances in electronics and optics have made it narrower. Research activities in terahertz frequencies have risen dramatically since that time, funding has increased by a factor of 100 in the last decade. The reviews by leading experts are of interest to researchers and engineers as well as advanced students.

Product DescriptionIntense Terahertz Excitation of Semiconductors presents the first comprehensive treatment of high-power terahertz applications to semiconductors and low-dimensional semiconductor structures. Terahertz properties of semiconductors are in the center of scientific activities because of the need of high-speed electronics. This research monograph bridges the gap between microwave physics and photonics. It focuses on a core topic of semiconductor physics providing a full description of the state of the art of the field.
The reader is introduced to new physical phenomena which occur in the terahertz frequency range at the transition from semi-classical physics with a classical field amplitude to the fully quantized limit with photons. The book covers a wide range of optical, optoelectronic, and nonlinear transport processes, presenting experimental results, clearly visualizing models and basic theories. Background information for future work and exhaustive references of current literature are given. A particularly valuable feature is the thorough discussion of various technical aspects of the terahertz range like the generation of high-power coherent radiation, optical components, instrumentation, and detection schemes of short intense pulses. The book complements, for the first time in form of a monograph, previous books on infrared physics which dealt with low-power optical and opto-electronic processes. It will be useful not only to scientists but also to advanced students who are interested in terahertz research.

Terahertz frequency sensing has a unique part to play in the detection and identification of materials and objects. This frequency range, corresponding to a wavelength of around 0.1 mm, can be used to identify materials from their molecular spectra and to produce images of concealed objects. Terahertz spectra of drugs of abuse and explosives presented by a number of the contributing authors show that the presence of these materials can be detected in envelopes, packages and through clothing.

The technology of terahertz detection has largely been developed around expensive and bulky femtosecond laser systems but, as described in this book, advances in semiconductor superlattice technology are leading to compact “electronic” sources such as the quantum cascade laser, two-terminal “Gunn” type oscillators and even a THz frequency amplifier. These advances towards electronic (as opposed to optical) THz systems mean that the technology will become portable and much less costly.

Terahertz remote sensing is also discussed with the possibility of detection over distances of up to 30m using existing technology or even through the use THz waves generated locally in the vicinity of a target using only air as the transducer.