[PDF] Broadband Terahertz Photonics eBook

Author : David Patrick Burghoff
Publisher :
Page : 190 pages
File Size : 36,47 MB
Release : 2014
Category :
ISBN :

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In recent years, quantum cascade lasers have emerged as mature semiconductor sources of light in the terahertz range, the frequency range spanning 1 to 10 THz. Though technological development has pushed their operating temperatures up to 200 Kelvin and their power levels up to Watt-level, they have remained unsuitable for many applications as a result of their narrow spectral coverage. In particular, spectroscopic and tomographic applications require sources that are both powerful and broadband. Having said that, there is no fundamental reason why quantum cascade lasers should be restricted to narrowband outputs. In fact, they possess gain spectra that are intrinsically broad, and beyond that can even be tailored to cover an octave-spanning range. This thesis explores the development of broadband sources of terahertz radiation based on quantum cascade lasers (QCLs). The chief way this is done is through the development of compact frequency combs based on THz QCLs, which are able to continuously generate milliwatt levels of terahertz power covering a fractional bandwidth of 14% of their center frequency. These devices operate on principles similar to microresonator-based frequency combs, and make use of the quantum cascade laser's fundamentally large nonlinearity to phase-lock the cavity modes. These devices will enable the development of ultra-compact dual comb spectrometers based on QCLs, and will potentially even act as complete terahertz spectrometers on a chip. This thesis also uses broadband terahertz time-domain spectroscopy to analyze the behavior of THz QCLs. By using QCLs as photoconductive switches, the usual limitations imposed by optical coupling are circumvented, and properties of the laser previously inaccessible can be directly observed. These properties include the gain and absorption of the laser gain medium, the populations of the laser's subbands, and properties of the waveguide like its loss and dispersion. Knowledge of these properties were used to guide frequency comb design, and were also used to inform simulations for designing better lasers.

Author : Jianjun Yu
Publisher : Springer Nature
Page : 275 pages
File Size : 45,76 MB
Release : 2021-06-28
Category : Science
ISBN : 9811631603

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This book highlights the comprehensive knowledge and latest progress in broadband terahertz (THz) technology. THz communication technology is believed to be one of the major choices that succeed the fifth-generation (5G) communication technology. With years of efforts, the author’s team has created a number of world records in the generation, transmission, and reception of ultra wideband THz signal, realizing the MIMO transmission and reception of THz communication, the THz signal transmission with communication capacity of 1 Tbit / s, and the optical fiber and THz integrated transmission. A variety of linear and nonlinear algorithms for multi-carrier and single-carrier THz communication systems are developed, which greatly improves the transmission performance of broadband systems. The book covers in details the broadband THz signal generation, long-distance transmission, and high sensitivity detection. It is of great reference value for researchers, engineers, and graduate students in optical and wireless communications.

Author : Francesco D'Angelo
Publisher :
Page : 101 pages
File Size : 14,95 MB
Release : 2016
Category :
ISBN : 9789463280402

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"Terahertz (THz) spectroscopy is a well-established technique which allows for measuring the complex-valued dielectric properties of materials, specifically semiconductors, in the THz range. As THz photons have a low energy, typically comparable to intraband transitions, they are ideal probes of important phenomena such as the momentum relaxation of charge carriers and optical phonons. Because of the intrinsic phase-matching limitations imposed by the materials employed in conventional THz emitters and detectors, most femtosecond-laser based THz spectrometers can only cover a narrow spectral range, typically 0.1-3 THz. However, by employing the same laser source as conventional THz spectrometers, an air-photonics based THz spectrometer can access a much broader spectral range, extending beyond 30 THz. As air is virtually non-dispersive, the optical-THz phase-matching condition is automatically met. As a result, intense, sub-50-fs electromagnetic transients can be achieved with THz air photonics. The enhanced characteristics in terms of time-resolution, bandwidth, and field strength offer unique opportunities for THz spectroscopy, such as monitoring the dynamics of the charge carriers on the timescale of the carrier-lattice interaction. In this thesis, we explore the capabilities of THz air photonics by performing steady-state ultra-broadband THz spectroscopy of some common polymers, and transient ultra-broadband THz spectroscopy of, respectively, solution processed methylammonium lead iodide perovskite films and undoped gallium arsenide. In addition, we present explicit guidelines for ultra-broadband transient THz spectroscopy, including a novel method for self-referenced signal acquisition minimizing the phase error, and a numerically-accurate approach to the transient reflectance data analysis."--Samenvatting auteur.

Author : Xi-cheng Zhang
Publisher : World Scientific
Page : 297 pages
File Size : 44,72 MB
Release : 2023-07-26
Category : Science
ISBN : 9811265658

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As a bridge between electronics and photonics, terahertz science and technology has made tremendous progress in the past decades. While terahertz wave generation from gas, solid and plasma with femtosecond laser excitation has been widely used, terahertz liquid photonics is a newly emerging topic in recent years. This book includes the most recent experimental results, theoretical analysis, and simulated calculations on terahertz emission and detection from liquid materials under ultrashort-pulse laser excitation, providing readers a comprehensive understanding of current developments in terahertz liquid photonics. By comparing with traditional sources, distinctive properties of terahertz wave generation from liquids are discussed in detail, which provides a new perspective in exploring laser-matter interactions.

Author : Abdolkarim Afroozeh, Reza Mosalanezhad, Seyed Ebrahim Pourmand, Alireza Zeinalinezhad
Publisher : American Academic Press
Page : 118 pages
File Size : 19,55 MB
Release : 2015-04-02
Category : Science
ISBN : 1631817280

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Terahertz technology is increasingly becoming an important part of communication systems such as fiber optic communication, RoF (radio over fiber) and wireless systems. The terahertz carrier wave can be generated by quantum transitions of light. In this study, terahertz wave will be generated using a micro ring resonator (MRR) for wide range of wavelengths in medical and RoF. THz radiation has also been used to differentiate tissues based on the abilities. The spectral information from THz pulses has been used to distinguish different types of soft tissues, such as muscle, fat, and kidney tissues.

Author : Susan L. Dexheimer
Publisher : CRC Press
Page : 358 pages
File Size : 42,73 MB
Release : 2017-12-19
Category : Technology & Engineering
ISBN : 142000770X

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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.

Author : Salman Alfihed
Publisher :
Page : 0 pages
File Size : 18,94 MB
Release : 2019
Category : Electronic books
ISBN :

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This chapter explores the terahertz (THz) emission from biased semiconductor photoconductive devices. The photoconductive device is an optoelectronic device that is able to emit broadband THz radiation under the optical excitation, by an ultrafast laser, in the existence of a bias field. This chapter explains the basic principle of photoconductive devices with focusing on the main device components, being the photoconductive material and the photoconductive structure. Then, various materials and structures are discussed toward improving the performance of the photoconductive THz emitters. Furthermore, the main limitations and considerations are presented with insight into the different saturation and screening effects due to the bias field and pump fluence. Ultimately, the recent advances and studies of photoconductive THz emitters are presented in terms of material and structure, including the quantum dots, the nanostructure, the use of dielectric materials, and the grating structure on the photoconductive surfaces.

Author : Yun-Shik Lee
Publisher : Springer Science & Business Media
Page : 348 pages
File Size : 26,15 MB
Release : 2009-03-02
Category : Technology & Engineering
ISBN : 0387095403

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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.

Author : Thomas Kürner
Publisher : Springer Nature
Page : 510 pages
File Size : 18,17 MB
Release : 2021-12-07
Category : Science
ISBN : 3030737381

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This book describes the fundamentals of THz communications, spanning the whole range of applications, propagation and channel models, RF transceiver technology, antennas, baseband techniques, and networking interfaces. The requested data rate in wireless communications will soon reach from 100 Gbit/s up to 1 Tbps necessitating systems with ultra-high bandwidths of several 10s of GHz which are available only above 200 GHz. In the last decade, research at these frequency bands has made significant progress, enabling mature experimental demonstrations of so-called THz communications, which are thus expected to play a vital role in future wireless networks. In addition to chapters by leading experts on the theory, modeling, and implementation of THz communication technology, the book also features the latest experimental results and addresses standardization and regulatory aspects. This book will be of interest to both academic researchers and engineers in the telecommunications industry.