Time-resolved microscopy of near-infrared to visible waveforms

Laser pulses, since their first demonstration in 1960, have reached an unprecedented level of temporal confinement: light fields on a femtosecond timescale are widely available and routine in modern experiments. Nowadays, ultrashort few-cycle electric fields can be utilized to generate even shorter, attosecond pulses, establishing a new direction of optics called attosecond physics. Such short light localization provides incredibly high temporal resolution, enabling direct observation of sub-cycle dynamics of the interaction of the fundamental waveform with matter in pump-probe measurements. Generation of attosecond pulses is an extremely sophisticated task, involving highly nonlinear processes and requiring a vacuum environment. Therefore, free-space methods that allow for the reconstruction of the time-varying field oscillations and direct performance of experiments with attosecond temporal precision are being developed. As the electric field is a function of time and space, the time-varying component is not always able to fully characterize the pulse. The large bandwidth associated with ultrashort pulses can be a reason for the formation of harmful spatio-temporal distortions. They often lead to a significant peak intensity reduction and unexpected experimental outcomes. The lack of direct access to the spatio-temporal evolution of near-infrared and visible few-cycle pulses is indeed of great concern. A potential spatio-temporal metrology technique can not only detect various distortions but also probe the properties of spatially inhomogeneous samples, extending the field-resolved spectroscopic toolbox to include spatial dimensions. This dissertation aims to advance a revolutionary metrology approach for absolute space-time characterization of electric fields by extending its capacity to the near-infrared and visible spectral regions. Its application in microscopy yields detection of subwavelength-localized structures in a wide-field geometry and extraction of spatio-temporal light-matter interaction with sub-cycle temporal resolution. This work is based on a well-established technique for complete field reconstruction, referred to as electro-optic sampling. The concept of electro-optic sampling relies on a phase-stable test field to be sampled that is coincident with an ultrashort probe pulse in an electro-optic crystal. Their nonlinear interaction induces a polarization rotation of the probe pulse that is sensitive to the strength and sign of the test electric field at a given instant. By varying the time delay between the pulses and employing dedicated instruments to read out the polarization rotation, it is possible to completely reconstruct the test field. Such instruments typically average over the spatial variations of the polarization rotation, yielding a single temporal waveform. Therefore, the assumption about homogeneous spatial distribution of the investigated field has to be made in these measurements. Alternatively, the dependence of the polarization rotation on the spatial coordinates in electro-optic sampling can be recorded using a standard imaging system. In this case, absolute spatio-temporal field information about the test electric field including the carrier envelope phase can be measured. We refer to this technique as electro-optic imaging. The optical scheme for electro-optic imaging was first introduced with relatively long pulses, in the terahertz spectral range (0.1-10 THz). In the present thesis, we dramatically extend the detection limits of electro-optic imaging towards shorter wavelengths, as low as 670 nm (450 THz). For the first time, the imaging technique is applied to demonstrate the full spatio-temporal reconstruction of few-cycle pulses in the near-infrared and visible regimes. Arbitrary spatio-temporal distortions of the laser pulses are detected and analyzed by converting time-dependent field snapshots into a hyperspectral image. Direct access to spatio-temporal dynamics of the electric field is utilized to investigate innovative metasurface optical devices and their incredible control over light properties. Metasurface optics allow diffraction-limited performance to be realized without cumbersome optical designs. The imaging apparatus can open a new door to comprehensive stu-dies of absolute space-time light confinement after the interaction of metasurface optics with an incident broadband field. It is particularly intriguing that not only the far-field but also near-field radiation can be accessed with electro-optic imaging in real time. This has been demonstrated in terahertz range, where microscopic samples placed directly on a thin electro-optic crystal were imaged with subwavelength resolution. A proof-of-concept of near-field detection in the near-infra-red range is shown by utilizing field enhancement with spherical microparticles. The imaging apparatus presented in this dissertation is expected to enrich the tools of attosecond metrology by including spatial dimensions. Additionally, this field-resolved microscopy method opens a novel path towards wide-field hyperspectral and label-free imaging with subwavelength resolution for applications in nanoscience and biology.Seit ihrer ersten Demonstration im Jahr 1960 haben Laserpulse ein noch nie dagewesenes Niveau der zeitlichen Begrenzung erreicht: Lichtfelder auf der Zeitskala von Femtosekunden sind weithin verfügbar und in modernen Experimenten Routine. Solche ultrakurze elektrische Felder mit nur wenigen Schwingungszyklen können z.B. dazu genutzt werden, um noch kürzere Pulse, Attosekunden-Pulse, zu erzeugen, wodurch eine neue Richtung der Optik etabliert wurde, die Attosekunden-Physik. Eine solche kurze Lichtlokalisierung bietet eine extrem hohe zeitliche Auflösung und ermöglicht die direkte Beobachtung der Subzyklus-Dynamik zwischen Licht und Materie mit Hilfe von Pump-Probe-Messungen. Die Erzeugung von Attosekunden-Pulsen ist eine äußerst anspruchsvolle Aufgabe, die hochgradig nichtlineare Prozesse beinhaltet und eine Vakuumumgebung erfordert. Daher werden Techniken entwickelt, die die Rekonstruktion der zeitvariablen Feldschwingungen und die direkte Durchführung von Experimenten mit Attosekunden-Zeitgenauigkeit in Normalbedingungen ermöglichen. Da das elektrische Feld eine Funktion von Zeit und Raum ist, kann eine Reduktion auf die zeitliche Komponente alleinden Laserpuls im Allgemeinen nicht vollständig charakterisieren. Die große Bandbreite, die mit ultrakurzen Pulsen einher geht, kann ein Grund für die Bildung von störenden raum-zeitlichen Verzerrungen sein. Diese können zu einer signifikanten Verringerung der Spitzenintensität und zu unerwarteten experimentellen Ergebnissen führen. Das nicht Vorhanden sein einer Möglichkeit die raum-zeitlichen Entwicklung von ultrakurzen Pulsen im nahen Infrarot und Sichtbaren direkt zu bestimmen ist bedauernswert. Eine solche raum-zeitliche Messtechnik könnte nicht nur verschiedene Verzerrungen quantifizieren, sondern erlaubt es auch die Eigenschaften räumlich inhomogener Proben auf die Pulse zu untersuchen und erweitert die feldaufgelöste spektroskopische Toolbox auf die räumliche Ausdehnung der Pulse. Ziel dieser Dissertation ist die Weiterentwicklung eines revolutionären Ansatzes zur absoluten Raum-Zeit-Charakterisierung elektrischer Felder, wobei seine Kapazität auf den nahen Infrarot- und Sichtbaren Spektralbereich ausgedehnt werden soll. Seine Implementierung in der Mikroskopie ermöglicht die Detektion von subwellenlängen-lokalisierten Strukturen in einer Weitfeldgeometrie und die Extraktion von raum-zeitlicher Licht-Materie-Wechselwirkung mit subzyklischer zeitlicher Auflösung. Diese Arbeit basiert auf einer weit verbreiteten Technik zur vollständigen Feldrekonstruktion, die als elektro-optische Abtasten bezeichnet wird. Das Konzept des elektro-optischen Abtastens beruht auf einem phasenstabilen Testfeld, das mit einem ultrakurzen Abfragepuls in einem elektro-optischen Kristall koinzidierend vermessen wird. Ihre nichtlineare Wechselwirkung induziert eine Polarisationsdrehung des Abfragepulses, die proportional zur Stärke und Richtungs des vorliegenden elektrischen Testfeldes ist. Durch Variation der Zeitverzögerung zwischen den Pulsen und durch den Einsatz spezieller Instrumente zum Auslesen der Polarisationsdrehung ist es möglich, das Testfeld vollständig zu rekonstruieren. Typischerweise mitteln solche Instrumente über die räumlichen Verteilung der Polarisationsdrehung, was zu einer einzigen zeitlichen Wellenform führt. Daher muss bei diesen Messungen die Annahme einer homogenen räumlichen Verteilung des untersuchten Feldes getroffen werden. Alternativ kann die Abhängigkeit der Polarisationsdrehung von den Raumkoordinaten bei der elektro-optischen Abtastung mit einem Standard-Bildgebungssystem aufgezeichnet werden. In diesem Fall kann die absolute raum-zeitliche Feldinformation über das elektrische Testfeld einschließlich der Phase zur Einhüllenden gemessen werden. Wir bezeichnen diese Technik als elektro-optische Bildgebung. Das optische Schema für die elektro-optische Bildgebung wurde zuerst mit relativ langen Pulsen im Terahertz-Spektralbereich (0.1-10 THz) eingeführt. In der vorliegenden Arbeit erweitern wir die Nachweisgrenze der elektro-optischen Bildgebung dramatisch in Richtung kürzerer Wellenlängen, bis hinunter zu 670 nm (450 THz). Erstmals wird die bildgebende Technik dazu benutzt, um die vollständige räumlich-zeitliche Rekonstruktion von Impulsen mit wenigen Zyklen im nahen Infrarot und im sichtbaren Bereich zu demonstrieren. Beliebige räumlich-zeitliche Verzerrungen der Laserpulse werden durch die Umwandlung zeitabhängiger Feldaufnahmen in ein hyperspektrales Bild detektiert und analysiert. Mit der direkten Charakterisierung der raum-zeitlichen Dynamik des elektrischen Feldes werden innovative Optiken, mit metastrukturierte Oberflächen, und deren unglaubliche Kontrolle über die Lichteigenschaften untersucht. Diese sogenannten Metasurface-Optiken erlauben beugungsbegrenzte Abbildungen durch eine einzige optische Komponente. Die elektro-optische Bildgebung bereitet den Weg zu umfassenden Untersuchungen der absoluten Raum-Zeit-Lichtverteilung eines breitbandigen einfallenden Lichtfeldes nach der Wechselwirkung mit der Metasurface-Optik. Besonders faszinierend ist, dass nicht nur die Fernfeld-, sondern auch die Nahfeldstrahlung mit der elektro-optischen Bildgebung in Echtzeit zugänglich ist. Dies wurde im Terahertz-Bereich demonstriert, wenn mikroskopische Proben, die direkt auf einem dünnen elektro-optischen Kristall platziert sind, nicht beugungslimitiert abgebildet wurden. Ein proof-of-concept der Nahfelddetektion im nahen Infrarotbereich wird durch die Nutzung der Felderhöhung mit sphärischen Mikropartikeln gezeigt. Der in dieser Dissertation vorgestellte bildgebende Apparat bereichert die Werkzeuge der Attosekunden-Metrologie durch die zusätzliche räumliche Auflösung. Darüber hinaus eröffnet diese feldaufgelöste mikroskopische Methode eine neue Möglichkeit einer hyperspektralen und markierungsfreien nicht beugungslimitierten Weitfeld-Bildgebung für Anwendungen in den Nanowissenschaften und der Biologie

Doppler coherence imaging of ion flows and temperatures in the MAGPIE helicon plasma

A snapshot coherence imaging system has been designed to measure brightness, flows and temperatures for argon ions in a helicon plasma with expected ion temperatures of ~1 eV and subsonic ion flows less than 1000 m/s. This technique measures Doppler information from the 488 nm ion spectral line, and encodes this information in the phase and contrast of an interferogram. Taking into account line-of-sight effects, demodulation of the interferogram yields a 2D spatial map of the ion temperatures and flows. At these plasma conditions, large interferometric delays (greater than 10^4 waves) are necessary to resolve the Doppler features. Passive stabilisation and an automated online calibration system was used to counteract thermally-induced phase drifts in the birefringent delay plates. The design features of this device are presented here. Measurements are presented of the ion brightness, flows and temperatures in the MAGnetised Plasma Interaction Experiment (MAGPIE) for an argon plasma at 3 mTorr gas pressure, forward power of 1 kW and a 0.08 T peak magnetic field (in a magnetic pinch configuration). Spatial scans taken longitudinally along the chamber shows the peak brightness occurs in the high magnetic field region and the radial profile is centrally peaked with secondary wing-like features. There are also high ion temperatures in the plasma edge which indicate a secondary ion heating mechanism. In the magnetic pinch region the azimuthal ion flows are largest and the axial ion flows show a flow reversal. Measurements of the brightness, ion temperature and ion flows are also examined over a range of magnetic field configurations and gas pressures and ion flow measurements are confirmed using a Mach probe. The results of this study demonstrate that, with careful consideration to instrument design, coherence imaging can be used to study ion features in cold plasmas. This opens opportunities for measurements of ion dynamics in laboratory-based plasmas across a range of research areas

Small business innovation research. Abstracts of 1988 phase 1 awards

Non-proprietary proposal abstracts of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA are presented. Projects in the fields of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robots, computer sciences, information systems, data processing, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

MIMO Systems

In recent years, it was realized that the MIMO communication systems seems to be inevitable in accelerated evolution of high data rates applications due to their potential to dramatically increase the spectral efficiency and simultaneously sending individual information to the corresponding users in wireless systems. This book, intends to provide highlights of the current research topics in the field of MIMO system, to offer a snapshot of the recent advances and major issues faced today by the researchers in the MIMO related areas. The book is written by specialists working in universities and research centers all over the world to cover the fundamental principles and main advanced topics on high data rates wireless communications systems over MIMO channels. Moreover, the book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity

Symbiotic Organisms Search Algorithm: theory, recent advances and applications

The symbiotic organisms search algorithm is a very promising recent metaheuristic algorithm. It has received a plethora of attention from all areas of numerical optimization research, as well as engineering design practices. it has since undergone several modifications, either in the form of hybridization or as some other improved variants of the original algorithm. However, despite all the remarkable achievements and rapidly expanding body of literature regarding the symbiotic organisms search algorithm within its short appearance in the field of swarm intelligence optimization techniques, there has been no collective and comprehensive study on the success of the various implementations of this algorithm. As a way forward, this paper provides an overview of the research conducted on symbiotic organisms search algorithms from inception to the time of writing, in the form of details of various application scenarios with variants and hybrid implementations, and suggestions for future research directions

The telecommunications and data acquisition report

Progress in the development and operations of the Deep Space Network is reported. Developments in Earth-based radio technology as applied to other research programs are also reported. These programs include geodynamics, astrophysics, and radio searching for extraterrestrial intelligence in the microwave region of the electromagnetic spectrum

Snapshot spectral imaging using image replication and birefringent interferometry : principles and applications

This thesis explores the image-replicating imaging spectrometer (IRIS). This relatively recent invention is a two-dimensional, snapshot spectral-imaging technology, capable of recording the spectral and spatial data from a scene instantaneously. Whereas conventional spectral-imaging technologies require multiple detector frames to record the entire data set, IRIS is able to record the data set in a single frame, a capability which is useful for highly dynamic scenes. The IRIS concept and the design of IRIS systems are explained in detail, and constraints on the performance of IRIS are determined. Practical issue in the use of IRIS systems are identi ed and solutions are identi ed and appraised. Some applications of IRIS are also shown, demonstrating its viability as a spectral imaging technology. Novel aspects of this work include the re nement of the IRIS design, demonstration of a registration algorithm for IRIS, designs for achromatic Wollaston prisms, a comparison of the IRIS technology with conventional spectral imaging technologies, and the application of IRIS to practical problems.Engineering and Physical Sciences Research Council (EPSRC)Selex Galile

Intelligent Circuits and Systems

ICICS-2020 is the third conference initiated by the School of Electronics and Electrical Engineering at Lovely Professional University that explored recent innovations of researchers working for the development of smart and green technologies in the fields of Energy, Electronics, Communications, Computers, and Control. ICICS provides innovators to identify new opportunities for the social and economic benefits of society.　 This conference bridges the gap between academics and R&D institutions, social visionaries, and experts from all strata of society to present their ongoing research activities and foster research relations between them. It provides opportunities for the exchange of new ideas, applications, and experiences in the field of smart technologies and finding global partners for future collaboration. The ICICS-2020 was conducted in two broad categories, Intelligent Circuits & Intelligent Systems and Emerging Technologies in Electrical Engineering