New Widely Tunable Room Temperature Terahertz Coherent Sources

The objective of this proposal was to develop a new type of THz semiconductor sources that are injection-pumped, efficient, compact, narrowband, tunable, and can operate at room temperature. The proposed device was a mid-infrared InGaAs/AlInAs Quantum Cascade Laser (QCLs) with the waveguide core containing a multi-functional coupled-quantum-well active region that supports both laser action in the mid-infrared and THz generation due to resonant coherent beating of two laser modes. During the course of the work a path was also found to substantially improve the temperature performance and directionality of conventional THz QCLs in which an electronic transition is used for the direct generation of THz radiation. The following was accomplished: first room temperature operation of an elctrically pumped quantum cascade laser based THz source, using intra-cavity nonlinear optics; record operating temperature (180K) of a conventional THz Quantum Cascade Laser, using a copper double metal waveguide for low loss; surface emitting THz QCLs with low beam divergence.

The book describes the most advanced techniques for generating coherent light in the mid-infrared region of the spectrum. These techniques represent diverse areas of photonics and include heterojunction semiconductor lasers, quantum cascade lasers, tunable crystalline lasers, fiber lasers, Raman lasers, and optical parametric laser sources. Offering authoritative reviews by internationally recognized experts, the book provides a wealth of information on the essential principles and methods of the generation of coherent mid-infrared light and on some of its applications. The instructive nature of the book makes it an excellent text for physicists and practicing engineers who want to use mid-infrared laser sources in spectroscopy, medicine, remote sensing and other fields, and for researchers in various disciplines requiring a broad introduction to the subject.

Terahertz Biomedical and Healthcare Technologies: Materials to Devices reviews emerging advances in terahertz biomedical and healthcare technologies, including advances in fundamental materials science research, device design and fabrication, applications, and challenges and opportunities for improved performance. In addition, the improvement of materials, optical elements, and measuring techniques are also explored. Other sections cover the design and development of wide bandgap semiconductors for terahertz device applications, including their physics, device modeling, characterization and fabrication concepts. Finally, the book touches on potential defense, medical imaging, internet of things, and the machine learning applications of terahertz technologies. Reviews the latest advances in the fundamental and applied research of terahertz technologies, covering key topics in materials science, biomedical engineering and healthcare informatics Includes applications of terahertz technologies in medical imaging, diagnosis and treatment Provides readers with an understanding of the machine learning, pattern recognition, and data analytics research utilized to enhance the effectiveness of terahertz technologies

Recent rapid advances in femtosecond technology have had a great impact on their industrial applications such as: ultrafast optoelectronic devices and optical telecommunication systems, ultrashort-pulse lasers and measurement systems, and the development of novel materials for ultrafast functions. In this book, a wealth of knowledge covering requirements in applications details of recent achievements in important technical areas is presented by world-prominent authors in a concise, systematic form. As a whole, this is the first comprehensive book on the emerging field of femtosecond technology.

A state-of-the-art overview of this rapidly expanding field, featuring fundamental theory, practical applications, and real-life examples.

The purpose of this book is two-fold. First, the various different methods of accessing the THz range are discussed, with a view to convince the reader that there have been qualitative and significant improvements over older, more conventional techniques. The text makes it clear that these improvements enable practical "real-world" applications of THz technology, in a manner which would not have been possible before. Second, the demonstrations and feasibility tests described serve as compelling evidence of the utility of such devices. Due to the unique characteristics of THz radiation and its interaction with materials, these devices have substantial advantages over other competing technologies in a number of different areas.

Broadly tunable lasers continue to have a tremendous impact in many and diverse fields of science and technology. From a renaissance in laser spectroscopy to Bose-Einstein condensation, the one nexus is the tunable laser. Tunable Laser Applications describes the physics and architectures of widely applied tunable laser sources. Fully updated and ex

Keeping abreast of the latest techniques and applications, this new edition of the standard reference and graduate text on laser spectroscopy has been completely revised and expanded. While the general concept is unchanged, the new edition features a broad array of new material, e.g., ultrafast lasers (atto- and femtosecond lasers) and parametric oscillators, coherent matter waves, Doppler-free Fourier spectroscopy with optical frequency combs, interference spectroscopy, quantum optics, the interferometric detection of gravitational waves and still more applications in chemical analysis, medical diagnostics, and engineering.