Nonlinear Dynamics in Multimode Optical Fibers

Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal and anomalous dispersion regimes. In the anomalous dispersion regime, the nonlinearity leads to a formation of spatiotemporal 3-D solitons. Unlike in single-mode fibers, these solitons are not unique and their properties can be modified through the additional degrees of freedom offered by these multimoded settings. In addition, soliton related processes such as soliton fission and dispersive wave generation will be also drastically altered in such multimode systems. Our theoretical work unravels some of the complexities of the underlying dynamics and helps us better understand these effects. The nonlinear dynamics in such multimode systems can be accelerated through a judicious fiber design. A cancelation of Raman self-frequency shifts and Blue-shifting multimode solitons were observed in such settings as a result of an acceleration of intermodal oscillations. Spatiotemporal instabilities in parabolic-index multimode fibers will also be discussed. In the normal dispersion regime, this effect can be exploited to generate an ultrabroad and uniform supercontinuum that extends more than 2.5 octaves. To do so, the unstable spectral regions are pushed away from the pump, thus sweeping the entire spectrum. Multimode parabolic pulses were also predicted and observed in passive normally dispersive tapered MMFs. These setting can obviate the harsh bandwidth limitation present in single-mode system imposed by gain medium and be effectively used for realizing high power multimode fiber lasers. Finally, an instant and efficient second-harmonic generation was observed in the multimode optical fibers. Through a modification of initial conditions, the efficiency of this process could be enhanced to a record high of %6.5

Structural requirements and launcher validation process for MECSE CubeSat

MECSE is the first CubeSat being developed at UBI - University da Beira Interior, and it is an under development nanosatellite, resulting from the collaboration between C-MAST - Center for Mechanical and Aerospace Science and Technologies and CEiiA - Centre of Engineering and Product Development. MECSE’s mission, aside from the education aims to provide hands-on experience to universitary students in space projects, it intends to demonstrate that is possible the manipulation of plasma layer using an electromagnetic field that will mitigate the RF - Radio Frequency blackout, which occurs when a space vehicle re-enter in the Earth’s Atmosphere. In this dissertation, an overview of the requirements for a structural configuration, design, dimensioning, verification and validation are presented, using several references. Nevertheless, the ECSS - European Cooperation for Space Standardization documents was where the most of the information was consulted, in order to identify and present the requirements from a systems engineering and structural perspective. Therefore, it was initially identified the main structural requirements, such as the mechanical environment, the interconnection between CubeSat and launcher, and the minimum natural frequency required for the satellite structure. Followed by the main structural requirements are the conditions under which the verifications and validations must be performed in a satellite structure. This led to the definition of the verification methods and to the organization, planning and methodology of the verification processes, which are normally used for a CubeSat validation. Knowing that the validation is only granted if the verifications and validation conditions are followed, applied and accomplished in the numerical and experimental verifications, such as for ROD’s - Reviews of Design and inspections. In a final phase of this work, a set of launchers was analysed with the objective of identifying a suitable proposal for MECSE project. The launchers Bloostar, Electron, LauncherOne and Vector-R were the launchers with better performance for the analysed parameters. The analysis of the various launchers was also carried out in order to recognize the most demanding mechanical environment among the cases taken into account, so that MECSE project could be designed and analysed according to the worst case scenario, while the final launcher is not selected. In this same phase a proposal is made for a possible approach to the verification process, with the main focus on the numerical models to be developed, on the experimental test methodology which was defined by a hybrid approach with a structural model, an engineering qualification model and a protoflight model, as well as identified the levels and duration of the tests and analyses to be performed in these same numerical and experimental models.MECSE é o primeiro CubeSat desenvolvido na UBI - Universidade da Beira Interior e é um nanosatélite em desenvolvimento resultante de uma parceria entre o C-MAST - Center for Mechanical and Aerospace Science and Technologies e o CEiiA - Centre of Engineering and Product Development. O objectivo do MECSE, além de ser educacional e de providenciar experiência prática a alunos universitários em projetos espaciais, tem como missão demonstrar que é possível manipular a camada de plasma, usando um campo electromagnético que irá permitir a mitigação da perda de sinal de rádio frequência que ocorre quando um veículo espacial reentra na atmosfera terrestre. Nesta dissertação, uma visão geral dos requisitos para a configuração, design, dimensionamento, verificação e validação são apresentados usando diversas referências, sendo dos documentos da ECSS - European Cooperation for Space Standardization que a maior parte da informação foi consultada, de forma a identificar e apresentar os requisitos de uma perspetiva da engenharia de sistemas e estrutural. Posto isto, foi inicialmente identificado os principais requisitos estruturais, tais como o ambiente mecânico, a interconexão entre CubeSat e lançador e a frequência natural mínima exigida à estrutura do satélite. De seguida foram assinaladas as condições pelas quais as verificações e validações se devem realizar numa estrutura espacial. Tendo as condições de verificação e validação levado à definição dos métodos de verificação e à organização, planeamento e metodologia dos processos de verificação que normalmente são aplicados num CubeSat para a sua validação. Sabendo que a validação só é obtida se forem seguidas as condições definidas para a realização das verificações numéricas e experimentais, tal como das ROD’s - Reviws of Design e das inspeções a proceder. Numa fase final deste trabalho, foi analisado um conjunto de lançadores com o objetivo de identificar uma proposta adequada para o projeto MECSE, tendo sido os lançadores Bloostar, Electron, LauncherOne e o Vector-R com melhor desempenho para os parâmetros analisados. A análise dos vários lançadores foi realizada também com o intuito de reconhecer qual o ambiente mecânico mais exigente de entre os casos tidos em conta, de forma a que o projeto MECSE possa ser desenhado e analisado segundo esse mesmo caso, enquanto o lançador final não é selecionado. Também nesta fase é realizada uma proposta para uma possível abordagem ao processo de verificação, com o principal foco para os modelos numéricos a desenvolver, para a metodologia de testes experimentais, foi definida uma abordagem híbrida com o intuito de ser construido um modelo estrutural, um modelo de qualificação de engenharia e um modelo protoflight, tal como é definido os níveis e duração dos testes a realizar nesses mesmos modelos numéricos e experimentais

Technology for large space systems: A special bibliography with indexes (supplement 04)

This bibliography lists 259 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1980 and December 31, 1980. Its purpose is to provide information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology Program. Subject matter is grouped according to systems, interactive analysis and design. Structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments

Time-resolved imaging of guided wave phenomena

In the past decade, increasing demand and rapid developments in classical and quantum sciences resulted in advanced novel multipixel single photon detector arrays engineered on a single electronic chip. Silicon single photon avalanche detector (Si-SPAD) is one of the mainstream solution for low level light detection in visible and near-infrared wavelength region due to the dependable amplification of light signal. This thesis mainly focusses on three key experiments to showcase the potential applications of a single photon detector (Megaframe 32) consists of 32×32 square array Si-SPADs with picosecond timing circuits. With ≈ 50 ps timing resolution, each SPAD can perform time-correlated single photon counting independently. First, the concept of multiplexed single-mode wavelength-to-time mapping (WTM) of multimode light was investigated. The spacetime imaging capability of the Megaframe was then demonstrated by imaging the spatial modes emerging from a few-mode fibre enabling WTM of spatial modes. Finally, timeresolved discrete imaging in laser inscribed photonic lattices was demonstrated. By placing a photonic lattice in a linear cavity and re-injecting the output mode profile back to the lattice, the propagation of light was measured in quasi-real time manner. The experimental demonstrations using Megaframe will find applications in Raman spectroscopy, soliton imaging, quantum optics, and discrete waveguide optics

Proceedings of the 8th International Conference on Civil Engineering

This open access book is a collection of accepted papers from the 8th International Conference on Civil Engineering (ICCE2021). Researchers and engineers have discussed and presented around three major topics, i.e., construction and structural mechanics, building materials, and transportation and traffic. The content provide new ideas and practical experiences for both scientists and professionals

Web GIS in practice X: a Microsoft Kinect natural user interface for Google Earth navigation

This paper covers the use of depth sensors such as Microsoft Kinect and ASUS Xtion to provide a natural user interface (NUI) for controlling 3-D (three-dimensional) virtual globes such as Google Earth (including its Street View mode), Bing Maps 3D, and NASA World Wind. The paper introduces the Microsoft Kinect device, briefly describing how it works (the underlying technology by PrimeSense), as well as its market uptake and application potential beyond its original intended purpose as a home entertainment and video game controller. The different software drivers available for connecting the Kinect device to a PC (Personal Computer) are also covered, and their comparative pros and cons briefly discussed. We survey a number of approaches and application examples for controlling 3-D virtual globes using the Kinect sensor, then describe Kinoogle, a Kinect interface for natural interaction with Google Earth, developed by students at Texas A&M University. Readers interested in trying out the application on their own hardware can download a Zip archive (included with the manuscript as additional files 1, 2, &3) that contains a 'Kinnogle installation package for Windows PCs'. Finally, we discuss some usability aspects of Kinoogle and similar NUIs for controlling 3-D virtual globes (including possible future improvements), and propose a number of unique, practical 'use scenarios' where such NUIs could prove useful in navigating a 3-D virtual globe, compared to conventional mouse/3-D mouse and keyboard-based interfaces