Download or read book Generation of Sub picosecond Terahertz Radiation by Laser produced Plasmas written by Harald Hamster and published by . This book was released on 1993 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sub picosecond Laser Produced Plasmas written by Margaret Murnane and published by . This book was released on 1989 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book THz Radiation from Laser written by Amrutha Gopal and published by . This book was released on 2021* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Terahertz waves are the last part of the electro magnetic spectrum to be measured and therefore relatively less explored compared to other spectral bands. They are considered to be harmless to living beings on exposure thanks to their low photon energy and possess many unique properties such as quasi static (~ps) electric and magnetic fields, which can observe, excite and control multitude of physical phenomena like solvation of water molecules in biological systems, non-equilibrium dynamics in unconventional superconductors, ferrites, semiconductors, magnetic materials and investigation of protein folding dynamics etc. thus making them the light wave of the future. Intense THz pulses with MV/cm fields are required for nonlinear vibrational spectroscopy, generation of high energy photons (XUV radiation) and for studying higher order nonlinear effects.There are various established techniques to generate high-power THz pulses. Laser-plasma based sources are a promising alternative to the established schemes due to their compactness and scalability. The work presented here investigates the generation of high-power, broadband terahertz radiation from thin foil targets at incident laser intensities above I > 10^18 W/cm^2. THz radiation from the foil rear surface has been proposed for the first time and showed that the radiation itself can be employed as a novel diagnostic to understand the charged particle dynamics. A detailed experimental investigation on the terahertz generation with respect to the incident laser and target parameters and its characterization are presented. Numerical calculations based on the charge particle detected from the rear surface was carried out and the results were compared with the experimental observations. The analysis points out that three main processes give rise to coherent THz radiation corresponding to the experimental observation of three temporally separated sub picosecond pulses.

Download or read book Sub picosecond Laser produced Plasmas written by Margaret Mary Murnane and published by . This book was released on 1989 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Generation of Intense Terahertz Sources by Ultrashort Laser Pulses written by Pedro González de Alaiza Martínez and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electromagnetic spectrum has a narrow frequency band, lying between microwaves and infrared, known as terahertz (THz) waves and extending from 0.1 to 30 THz. These waves, inaccessible until a recent past because they are situated at the boundary between electronics and optics, are raising interest because of their promising applications in several areas such as medical imaging and remote identification of explosives. However, producing intense THz radiation with amplitude belonging to the GV/m range should allow us to probe efficiently remote materials, which still remains an open issue. The goal of this thesis is precisely to study the generation of such intense THz radiation by coupling two ultrashort laser pulses -the fundamental and its second harmonic- able to ionize a gas target (for example, air or argon). The plasma created by photoionization then acts as a nonlinear frequency converter, transforming part of the laser energy into the THz band via a wide range of physical mechanisms including the Kerr effect, the photoionization and ponderomotive forces induced inside the plasma. By means of an analytical and numerical modeling of these key mechanisms, we have comprehensively examined the generation of THz pulses at laser intensities ranging from characteristic intensities met in laser filamentation (1012-1014 W cm−2) to sub-relativistic intensities (1015-1018 W cm−2), this latter intensity range having been little investigated so far in this domain. It is already known that at low intensities laser-induced photionization dominates in terahertzgeneration, which strongly depends on the configuration of the laser colours (or harmonics). We demonstrate here that, beyond the classical two-colour laser setup, coupling several laser frequencies following the harmonics of a sawtooth waveform is optimal to enhance THz production. Simulations predict a laser-to-THz energy conversion efficiency of 2% with four colours, a record value unequalled so far. Moreover, with an experiment realized in air, we identify the Kerr signature in the emitted THz spectrum, which, even weaker, looks complentary to the plasma signature. When the intensity of the laser pulse is increased beyond 1015 W cm−2, we prove that the growth of the emitted terahertz radiation is nonmonotonic, due to the fact that that there exists an optimal intensity value that maximizes the THz energy produced by each electronic shell of the irradiated atom. Finally, we have studied in 2D geometry the combined effect of photoionization and ponderomotive forces at intensities close to 1018 W cm−2, allowing us to obtain THz fields exceeding the GV/m threshold in argon. These latter forces increase with the laser intensity and thus open interesting perspectives for the generation of very intense terahertz fields in the relativistic regime of laser-matter interaction.

Download or read book Experiments and Computational Theory for Electrical Breakdown in Critical Components written by and published by . This book was released on 2016 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the development of ultra-short pulse laser (USPL) induced terahertz (THz) radiation to image electronic plasmas during electrical breakdown. The technique uses three pulses from two USPLs to (1) trigger the breakdown, (2) create a 2 picosecond (ps, 10 -12 s), THz pulse to illuminate the breakdown, and (3) record the THz image of the breakdown. During this three year internal research program, sub-picosecond jitter timing for the lasers, THz generation, high bandwidth (BW) diagnostics, and THz image acquisition was demonstrated. High intensity THz radiation was optically-induced in a pulse-charged gallium arsenide photoconductive switch. The radiation was collected, transported, concentrated, and co-propagated through an electro-optic crystal with an 800 nm USPL pulse whose polarization was rotated due to the spatially varying electric field of the THz image. The polarization modulated USPL pulse was then passed through a polarizer and the resulting spatially varying intensity was detected in a high resolution digital camera. Single shot images had a signal to noise of %7E3:1. Signal to noise was improved to %7E30:1 with several experimental techniques and by averaging the THz images from %7E4000 laser pulses internally and externally with the camera and the acquisition system (40 pulses per readout). THz shadows of metallic films and objects were also recorded with this system to demonstrate free-carrier absorption of the THz radiation and improve image contrast and resolution. These 2 ps THz pulses were created and resolved with 100 femtosecond (fs, 10 -15 s) long USPL pulses. Thus this technology has the capability to time-resolve extremely fast repetitive or single shot phenomena, such as those that occur during the initiation of electrical breakdown. The goal of imaging electrical breakdown was not reached during this three year project. However, plans to achieve this goal as part of a follow-on project are described in this document. Further modifications to improve the THz image contrast and resolution are proposed, and after they are made, images of photo-induced carriers in gallium arsenide and silicon will be acquired to evaluate image sensitivity versus carrier density. Finally electrical breakdown will be induced with the first USPL pulse, illuminated with THz radiation produced with the second USPL pulse and recorded with the third USPL pulse.

Download or read book Recent Optical and Photonic Technologies written by Ki Young Kim and published by BoD – Books on Demand. This book was released on 2010-01-01 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research and development in modern optical and photonic technologies have witnessed quite fast growing advancements in various fundamental and application areas due to availability of novel fabrication and measurement techniques, advanced numerical simulation tools and methods, as well as due to the increasing practical demands. The recent advancements have also been accompanied by the appearance of various interdisciplinary topics. The book attempts to put together state-of-the-art research and development in optical and photonic technologies. It consists of 21 chapters that focus on interesting four topics of photonic crystals (first 5 chapters), THz techniques and applications (next 7 chapters), nanoscale optical techniques and applications (next 5 chapters), and optical trapping and manipulation (last 4 chapters), in which a fundamental theory, numerical simulation techniques, measurement techniques and methods, and various application examples are considered. This book deals with recent and advanced research results and comprehensive reviews on optical and photonic technologies covering the aforementioned topics. I believe that the advanced techniques and research described here may also be applicable to other contemporary research areas in optical and photonic technologies. Thus, I hope the readers will be inspired to start or to improve further their own research and technologies and to expand potential applications. I would like to express my sincere gratitude to all the authors for their outstanding contributions to this book.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2002 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sensing with Terahertz Radiation written by Daniel Mittleman and published by Springer. This book was released on 2013-02-26 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book All electronic Generation and Detection of Terahertz Free space Radiation with Subpicosecond Pulses written by Daniel Warren Van Der Weide and published by . This book was released on 1992 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Review written by and published by . This book was released on 1996-06 with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publishes papers that report results of research in statistical physics, plasmas, fluids, and related interdisciplinary topics. There are sections on (1) methods of statistical physics, (2) classical fluids, (3) liquid crystals, (4) diffusion-limited aggregation, and dendritic growth, (5) biological physics, (6) plasma physics, (7) physics of beams, (8) classical physics, including nonlinear media, and (9) computational physics.

Download or read book Terahertz Liquid Photonics written by Xi-cheng Zhang and published by World Scientific. This book was released on 2023-07-26 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Introduction to THz Wave Photonics written by Xi-Cheng Zhang and published by Springer Science & Business Media. This book was released on 2009-12-01 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Terahertz (THz) radiation, which is electromagnetic radiation in a frequency int- val from 0.3 to 10 THz (1 mm–30 ?m wavelength), is the next frontier in science and technology. This band occupies a large portion of the electromagnetic sp- trum between the infrared and microwave bands. Basic research, new initiatives, and developments in advanced sensing and imaging technology with regard to the THz band remain unexplored compared to the relatively well-developed science and technology in the microwave and optical frequencies. Historically, THz technologies were used mainly within the astronomy c- munity for studying the background of cosmic far-infrared radiation, and by the laser-fusion community for the diagnostics of plasmas. Since the ?rst demonstration of THz wave time-domain spectroscopy in the late 1980s, there has been a series of signi?cant advances (particularly in recent years) as more intense THz sources and higher sensitivity detectors provide new opportunities for understanding the basic science in the THz frequency range.

Download or read book Longitudinally Polarised Terahertz Radiation for Relativistic Particle Acceleration written by Matthew. J Cliffe and published by Springer. This book was released on 2017-01-11 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book elaborates on the acceleration of charged particles with ultrafast terahertz electromagnetic radiation. It paves the way for new, and improves many aspects of current, accelerator applications. These include providing shorter electron bunches for ultrafast time-resolved pump-probe spectroscopy, enabling complex longitudinal profiles to be imparted onto charged particle bunches and significantly improving the ability to synchronise an accelerator to an external laser. The author has developed new sources of terahertz radiation with attractive properties for accelerator-based applications. These include a radially biased large-area photoconductive antenna (PCA) that provided the largest longitudinally polarised terahertz electric field component ever measured from a PCA. This radially biased PCA was used in conjunction with an energy recovery linear accelerator for electron acceleration experiments at the Daresbury Laboratory. To achieve even higher longitudinally polarised terahertz electric field strengths, and to be able to temporally tune the terahertz radiation, the author investigated generation within non-linear optical crystals. He developed a novel generation scheme employing a matched pair of polarity inverted magnesium-oxide doped stoichiometric lithium niobate crystals, which made it possible to generate longitudinally polarised single-cycle terahertz radiation with an electric field amplitude an order of magnitude larger than existing sources.

Download or read book Terahertz Aqueous Photonics written by Qi Jin and published by . This book was released on 2020 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Developing efficient and robust terahertz (THz) sources is of incessant interest in the THz community for their wide applications. For instance, THz waves are widely applied to nondestructive evaluation and biomedical imaging. Intense THz fields can be used for nonlinear interactions and electron acceleration. With successive efforts in past decades, numerous groups have achieved THz wave generation from solids, gases, and plasmas. However, liquid, especially liquid water has never been demonstrated as a THz source. One main reason leading the impediment is that water has strong absorption characteristics in the THz frequency regime. In this dissertation, a thin water film under intense laser excitation was introduced as the THz source to mitigate the considerable loss of THz waves from the absorption. Laserinduced plasma formation associated with a ponderomotive force-induced dipole model was proposed to explain the generation process. Compared with gas targets, water has a lower photon-ionization energy, but three orders of magnitude higher molecular density. Compared with solid targets, water does not suffer from permanent damage caused by the intense laser pulses. For the one-color excitation scheme, the water film generates a higher THz electric field than the air does under the identical experimental condition. Unlike the case of air, THz wave generation from liquid water prefers a subpicosecond (200-800 fs) laser pulse rather than a femtosecond pulse (~50 fs). This observation results from the plasma generation process in water. For the two-color excitation scheme, the THz electric field is enhanced by one-order of magnitude in comparison with the one-color case. Meanwhile, coherent control of the THz field is achieved by adjusting the relative phase between the fundamental pulse and the second-harmonic pulse. To eliminate the total internal reflection of THz waves at the water-air interface of a water film, a water line produced by a syringe needle was used to emit THz waves. As expected, more THz radiation can be coupled out and detected. As a supplement to the research of Terahertz Aqueous Photonics, THz wave generation from other liquids were also tested. For example, the THz electric field obtained from ?-Pinene is 1.8-times stronger than that from water under the same experimental condition, which mainly arises from the much weaker absorption of ?-Pinene for THz waves. Historically liquid water has been sworn off as a THz source. This dissertation not only demonstrates that water can be used to generate THz waves but also contributes to enthralling insight into the development of intense THz sources. The work also indicates that THz waves can be a great tool for the investigation of laser-liquid interaction"--Pages xii-xiii.

Download or read book Microwave Photonics Second Edition written by Chi H. Lee and published by CRC Press. This book was released on 2013-03-21 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-frequency systems. The book features contributions by leading international researchers, many of whom are pioneers in the field. They examine wave generation, measurement, detection, control, and propagation in detail, as well as the devices and components that enable ultrawide-band and ultrafast transmission, switching, and signal processing. These devices and components include optical-controlled microwave devices, optical transmitters, receivers, switching devices, detectors, and modulators. The book explores the theory, techniques, and technologies that are fueling applications such as radio-over-fiber, injection-locked semiconductor lasers, and terahertz photonics. Throughout, the contributors share insights on overcoming current limitations and on potential developments. What’s New in This Edition Two new chapters, on fiber Bragg gratings for microwave photonics applications and ultrawide-band sub-THz photonic wireless links Updates throughout, reflecting advances in the field New illustrations in each chapter Fully illustrated with more than 300 figures and tables, this book offers a detailed, wide-ranging overview of the current state and future directions of this burgeoning technology.

Download or read book Terahertz Biomedical Science and Technology written by Joo-Hiuk Son and published by CRC Press. This book was released on 2014-06-13 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of applications including scientific spectroscopy, security screening, and medical imaging have benefitted from the development and utilization of new and emerging terahertz (THz) generation and detection techniques. Exploring recent discoveries and the advancements of biological behaviors through THz spectroscopy and imaging and the development of THz medical techniques, Terahertz Biomedical Science and Technology contains contributions from scientists and researchers in the terahertz biomedical field and is exclusively dedicated to new and emerging terahertz biomedical research and applications. This text offers an assessment of terahertz technology, and provides a compilation of fundamental biological studies conducted using terahertz waves. It introduces THz electromagnetic waves as a new tool for convergent studies, includes laser-based generation techniques and solid-state devices, contains a number of detectors, and discusses high-field generation methods. The material covers recent advancements in terahertz imaging for medical applications—most specifically in cancer diagnosis—reviewing the current status of the THz imaging technique for diagnosing cancers, and exploring the potential medical applications of THz radiation. It also considers the development of future medical applications using terahertz technology. Summarizes the recent progress made in THz waveguides, which are absolutely essential in the development of THz endoscopes Describes the dynamic imaging of drug absorption in skin, exploiting the sensitivity of THz waves to pharmaceutical materials Explores the principle and applications of THz molecular imaging techniques using nanoparticle probes Scientists and engineers involved in biological research and medical applications using optical techniques, as well as graduate students and instructors in optics, physics, electrical engineering, biology, chemistry, and medicine can benefit from this text which highlights new and emerging biomedical studies utilizing novel THz wave techniques.