Author: Hampus Lundén
Publisher: Linköping University Electronic Press
ISBN: 9176851133
Category :
Languages : sv
Pages : 73
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Book Description
High power laser pulses can be a threat to optical sensors, including the human eye. Traditionally this threat has been alleviated by colour filters that block radiation in chosen wavelength ranges. Colour filters’ main drawback is that they block radiation regardless of it being useful or damaging, information is lost for wavelengths at which the filter is active. Protecting the entire wavelength range of a sensor would block or strongly attenuate the radiation needed for the operation of the sensor. Sol-gel glasses highly doped with optically non-linear chromophores have previously shown high optical quality in combination with efficient optical power limiting (OPL) through reverse saturable absorption (RSA). These filters transmit visible light unless the light fluence is above a certain threshold. A key design consideration of laser protection filters is linear absorption in relation to the threshold level. A high linear absorption means that the user’s view is degraded by the filter. To model the photokinetics of RSA chromophores, the five-level population model is widely used. It consists of three singlet and two triplet levels. Model parameters relevant for OPL performance include linear absorption cross-sections, two-photon absorption (2PA) cross-sections, lifetimes, quantum yields and inter-system-crossing (ISC) times. The dominant design paradigm is to have a highly absorbing and long-lived triplet state that is quickly populated by ISC during the beginning of a laser pulse. To simultaneously achieve a lower threshold and linear absorption a vast number of materials for self-activated filters were evaluated, either as bulk glasses or solutions. An f/5 setup was used to evaluate their OPL performance while several photophysical measurements were performed to gain an understanding of system behaviour. The first three series of methyltriethoxysilane (MTEOS) Sol-Gel glasses were doped with gold nanoparticles either solely, or with one of two Pt-acetylide chromophores. One with shorter conjugated ligands, the second with similar but longer conjugated ligands. Finally, a series of multi-branched fluorene chromophores were evaluated in solution. Their central moiety was either an organic benzene unit or an ISC promoter in the form of para-dibromobenzene or a platinum(II)-alkynyl unit. For the gold nanoparticle doped glasses, the lower performance Pt-acetylide with short ligands had its OPL threshold lowered at 600nm while the glasses doped with only gold nanoparticles showed no OPL at all. Secondly, the enhancement was most pronounced for very low gold nanoparticle concentrations. While gold nanoparticles alone showed good OPL performance at 532 nm, at this wavelength neither Pt-acetylide showed an obvious OPL enhancement beyond linear absorption losses from codoping with gold nanoparticles. The improved OPL performance at 600 nm was attributed to stronger 2PA, by electric field enhancement from the gold nanoparticles. The lack of detectable OPL improvement for 532 nm and for the higher performance Pt-Acetylide chromophore with long ligands were qualitatively explained by a lower sensitivity to 2PA on system performance. A degraded performance from linear absorption by excess nanoparticles in front of the focus explained the weakening of the enhancement at higher gold nanoparticle concentrations. All three fluorene chromophores, including the chromophore without a central ISC promoter, showed broadband OPL through the visible spectrum. The OPL performance of the two chromophores with ISC promoters was expected considering their transient absorption at microsecond time-scales. For the fluorene chromophore without an ISC-promoter, ultra-fast transient absorption was used to identify singlet excited state absorption as the source of the OPL performance. Both of these series of experiments demonstrate how a simplistic view of simply increasing desired photophysical parameters, e.g. effective 2PA cross-section or ISC quantum yield, do not always result in a noticeable increase in system performance. By employing numerical population models it was possible to identify which parameters had the highest impact on OPL performance. Laserpulser med hög effekt kan vara ett hot mot optiska sensorer, inklusive det oskyddade ögat. Traditionellt har detta hot hanterats med färgfilter som stoppar strålning inom valda våglängdsband. Färgfilters huvudsakliga begränsning ligger i att de tar bort strålning oberoende av om den är användbar eller skadlig, att information försvinner för de våglängder filtret skyddar för. Skydd över hela det våglängdsband en sensor verkar i skulle stoppa eller kraftigt försvaga strålningen som sensorn behöver för att fungera. Sol-gel glas högdopade med optiskt icke-linjära molekyler har tidigare visat hög optisk kvalité i kombination med en effektiv optisk effektbegränsning (OPL) via omvänd blekning (RSA). Dessa filter transmitterar synligt ljus så länge ljusets fluens (pulsenergi per area [J cm-2]) inte ligger över en viss begränsningsnivå. En nyckelfaktor i designen av laserskyddsfilter är linjärabsorption kontra begränsningsnivå. Genom att öka kromoforkoncentrationen så kan begränsningsnivån sänkas till kostnad av ökad linjärabsorption. Detta betyder dock att användarens omvärldsuppfattning genom filtret riskerar att minska. För att modellera fotokinetiken av RSA-molekyler har femnivåpopulationsmodellen varit vida använd. Den består av tre singlet-nivåer och två tripletnivåer. Modellparametrar relevanta för OPL-prestanda innefattar kvantverkningsgrader, olika övergångars linjärabsorptionstvärsnitt, tvåfotonsabsorptionstvärsnitt och livstider samt halveringstider för överföring mellan singlet och triplettillstånd. Den dominanta designparadigmen är att ha ett hög- absorberande och långlivat tripletläge som snabbt populeras i början av en laserpuls. För att samtidigt uppnå en lägre begränsningsnivå och lägre linjärabsorption utvärderades ett flertal självaktiverade filter, antingen i form av glas eller i vätskelösning. En f/5-uppställning användes för att utvärdera deras OPLprestanda medan en mängd fotofysiska mätningar utfördes för att få en förståelse för deras systembeteende. De tre första serierna av MTEOS Sol-Gel glas var dopade med guldnanopartiklar antingen enbart, eller med en av två Pt(II)-acetylidmolekyler. Den första hade kortare konjugerade ligandarmar, den andra var liknande men hade längre ligandarmar. Slutligen utvärderades en serie av flerarmade flourenmolekyler i vätskelösning. Deras centrala enhet bestod antingen av en organisk bensenring eller en ISC-gynnare i form av para-dibromobensen eller en Pt(II)-acetylidenhet. Guldnanopartiklarna kunde förstärka OPL-prestandan för enbart den mindre effektiva korta Pt(II)-acetylidmolekylen på 600nm men ej 532nm. Filtren dopade med enbart guldnanopartiklar visade god prestanda på 532nm men ingen på 600nm. Alla tre fluorenmolekyler visade OPL genom det synliga spektrat, även den molekylen utan ISC-gynnare. Både dessa serier experiment demonstrerar hur ett förenklat angreppsätt med att enbart öka eftertraktade fotofysiska parametrar, t.ex. effektivt 2PA-tvärsnitt eller ISC-kvantverkningsgrad, inte alltid resulterar i märkbart ökad systemprestanda. Genom att använda numeriska populationsmodeller visas hur det är möjligt att identifiera vilka parametrar som har den största inverkan på OPL-prestanda.
Author: Hari Singh Nalwa
Publisher: CRC Press
ISBN: 9780849389238
Category : Technology & Engineering
Languages : en
Pages : 898
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Book Description
This book presents an excellent overview of the exciting new advances in nonlinear optical (NLO) materials and their applications in emerging photonics technologies. It is the first reference source available to cover every NLO material published through 1995! All theoretical approaches, measurement techniques, materials, technologies, and applications are covered. With more than 1,800 bibliographic citations, 324 figures, 218 tables, and 812 equations, this book is an invaluable reference source for graduate and undergraduate students, researchers, scientists and engineers working in academia and industries in chemistry, solid-state physics, materials science, optical and polymer engineering, and computational science.
Author: Jerome V. Moloney
Publisher: Springer Science & Business Media
ISBN: 9780387985817
Category : Business & Economics
Languages : en
Pages : 270
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Book Description
Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.
Author: Robert Boyd
Publisher: Academic Press
ISBN: 0323148204
Category : Science
Languages : en
Pages : 494
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Book Description
Contemporary Nonlinear Optics discusses the different activities in the field of nonlinear optics. The book is comprised of 10 chapters. Chapter 1 presents a description of the field of nonlinear guided-wave optics. Chapter 2 surveys a new branch of nonlinear optics under the heading optical solitons. Chapter 3 reviews recent progress in the field of optical phase conjugation. Chapter 4 discusses ultrafast nonlinear optics, a field that is growing rapidly with the ability of generating and controlling femtosecond optical pulses. Chapter 5 examines a branch of nonlinear optics that may be termed nonlinear quantum optics. Chapter 6 reviews the new field of photorefractive adaptive neural networks. Chapter 7 presents a discussion of recent successes in the development of nonlinear optical media based on organic materials. Chapter 8 reviews the field of nonlinear optics in quantum confined structures. Chapter 9 reviews the field of nonlinear laser spectroscopy, with emphasis on advances made during the 1980s. Finally, Chapter 10 reviews the field of nonlinear optical dynamics by considering nonlinear optical systems that exhibit temporal, spatial, or spatio-temporal instabilities. This book is a valuable source for physicists and other scientists interested in optical systems and neural networks.
Author: Qiang Wang
Publisher: John Wiley & Sons
ISBN: 3527350594
Category : Technology & Engineering
Languages : en
Pages : 373
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Book Description
Comprehensive resource covering concepts, perspectives, and skills required to understand the preparation, nonlinear optics, and applications of two-dimensional (2D) materials Bringing together many interdisciplinary experts in the field of 2D materials with their applications in nonlinear optics, Two-Dimensional Materials for Nonlinear Optics covers preparation methods for various novel 2D materials, such as transition metal dichalcogenides (TMDs) and single elemental 2D materials, excited-state dynamics of 2D materials behind their outstanding performance in photonic devices, instrumentation for exploring the photoinduced excited-state dynamics of the 2D materials spanning a wide time scale from ultrafast to slow, and future trends of 2D materials on a series of issues like fabrications, dynamic investigations, and photonic/optoelectronic applications. Powerful nonlinear optical characterization techniques, such as Z-scan measurement, femtosecond transient absorption spectroscopy, and microscopy are also introduced. Edited by two highly qualified academics with extensive experience in the field, Two-Dimensional Materials for Nonlinear Optics covers sample topics such as: Foundational knowledge on nonlinear optical properties, and fundamentals and preparation methods of 2D materials with nonlinear optical properties Modulation and enhancement of optical nonlinearity in 2D materials, and nonlinear optical characterization techniques for 2D materials and their applications in a specific field Novel nonlinear optical imaging systems, ultrafast time-resolved spectroscopy for investigating carrier dynamics in emerging 2D materials, and transient terahertz spectroscopy 2D materials for optical limiting, saturable absorber, second and third harmonic generation, nanolasers, and space use With collective insight from researchers in many different interdisciplinary fields, Two-Dimensional Materials for Nonlinear Optics is an essential resource for materials scientists, solid state chemists and physicists, photochemists, and professionals in the semiconductor industry who are interested in understanding the state of the art in the field.
Author: Frank Träger
Publisher: Springer Science & Business Media
ISBN: 3642194095
Category : Science
Languages : en
Pages : 1704
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Book Description
This new edition features numerous updates and additions. Especially 4 new chapters on Fiber Optics, Integrated Optics, Frequency Combs and Interferometry reflect the changes since the first edition. In addition, major complete updates for the chapters: Optical Materials and Their Properties, Optical Detectors, Nanooptics, and Optics far Beyond the Diffraction Limit. Features Contains over 1000 two-color illustrations. Includes over 120 comprehensive tables with properties of optical materials and light sources. Emphasizes physical concepts over extensive mathematical derivations. Chapters with summaries, detailed index Delivers a wealth of up-to-date references.
Author: Hari Singh Nalwa
Publisher: CRC Press
ISBN: 0429611617
Category : Technology & Engineering
Languages : en
Pages : 896
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Book Description
The field of nonlinear optics emerged three decades ago with the development of the first operating laser and the demonstration of frequency doubling phenomena. These milestone discoveries not only generated much interest in laser science, but also set the stage for future work on nonlinear optics. This book presents an excellent overview of the exciting new advances in nonlinear optical (NLO) materials and their applications in emerging photonics technologies. It is the first reference source available to cover every NLO material published through 1995. All theoretical approaches, measurement techniques, materials, technologies, and applications are covered. With more than 1,800 bibliographic citations, 324 figures, 218 tables, and 812 equations, this book is an invaluable reference source for graduate and undergraduate students, researchers, scientists and engineers working in academia and industries in chemistry, solid-state physics, materials science, optical and polymer engineering, and computational science.
Author: Richard L. Sutherland
Publisher: CRC Press
ISBN: 9780824742430
Category : Technology & Engineering
Languages : en
Pages : 1122
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Book Description
Examining classic theories, experimental methods, and practical formulas for exploration of the core topics in nonlinear optics, the second edition of this acclaimed text was extensively revised to reflect recent advances in the analysis and modification of material properties for application in frequency conversion, optical switching and limiting, multiphoton absorption, and electro-optic effects. Handbook of Nonlinear Optics, Second Edition contains additional chapters on ultrafast characterization techniques, laser flash photolysis, and the electro-optic effect as well as expanded coverage of nonlinear optics in fibers and pulsed two-beam coupling.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309087007
Category : Technology & Engineering
Languages : en
Pages : 660
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Book Description
In order to achieve the revolutionary new defense capabilities offered by materials science and engineering, innovative management to reduce the risks associated with translating research results will be needed along with the R&D. While payoff is expected to be high from the promising areas of materials research, many of the benefits are likely to be evolutionary. Nevertheless, failure to invest in more speculative areas of research could lead to undesired technological surprises. Basic research in physics, chemistry, biology, and materials science will provide the seeds for potentially revolutionary technologies later in the 21st century.
Author: Richard L. Sutherland
Publisher: CRC Press
ISBN: 1135541183
Category : Technology & Engineering
Languages : en
Pages : 976
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Book Description
Examining classic theories, experimental methods, and practical formulas for exploration of the core topics in nonlinear optics, the second edition of this acclaimed text was extensively revised to reflect recent advances in the analysis and modification of material properties for application in frequency conversion, optical switching and limiting,
