Electromagnetics and Photonics Commons^™

Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar

Electronic Theses and Dissertations

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 …

Single Mode Wavelength-Tunable Thulium Fiber, Dong Jin Shin

Electronic Theses and Dissertations

Thulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75μm and ends at around 2.15μm, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them uniquely suited for applications such as remote sensing. At the moment, high power beam propagation of continuous wave laser through the atmosphere in the mid-infrared range is yet to …

2 Micron Fiber Lasers: Power Scaling Concepts And Limitations, Alex Sincore

Electronic Theses and Dissertations

Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses …

Coexistence And Secure Communication In Wireless Networks, Saygin Bakşi

Electrical & Computer Engineering Theses & Dissertations

In a wireless system, transmitted electromagnetic waves can propagate in all directions and can be received by other users in the system. The signals received by unintended receivers pose two problems; increased interference causing lower system throughput or successful decoding of the information which removes secrecy of the communication. Radio frequency spectrum is a scarce resource and it is allocated by technologies already in use. As a result, many communication systems use the spectrum opportunistically whenever it is available in cognitive radio setting or use unlicensed bands. Hence, efficient use of spectrum by sharing users is crucial to increase maximize …

Coupling Radio Frequency Energy Via The Embedded Rebar Cage In A Reinforced Concrete Structure For The Purpose Of Concrete Degradation Sensing, Ryan Campiz

UNF Graduate Theses and Dissertations

This study focuses on utilizing an energy harvesting system in which a dedicated Radio Frequency (RF) power source transmits RF power via rebar in a reinforced concrete column. The RF power is received and decoupled by a receiver, and is then rectified, boosted, and stored as electrical energy in a supercapacitor, later to be used to make measurements, process data, and communicate to the source via rebar. Two design attempts are presented in this study: (a) one uses single line conduction at 2.4 GHz for RF power transfer; (b) the other uses a more conventional two-line conduction at 8.0 kHz …

Controlling Light With Metadevices, Xu Zhang

Dissertations, Master's Theses and Master's Reports

The development of metamaterials provides a new way to manipulate electromagnetic waves by sub-wavelength artificial structures, and hence brings new properties and functionalities that cannot be found with conventional materials. This leads to the possibility of previously unthought-of applications, including perfect lenses, invisibility cloaks, and perfect absorbers. However, several critical challenges need to be addressed before transiting from intriguing scientific findings to real-world usable devices.

This dissertation deals with two challenges regarding the practical use of metamaterials. Firstly, fabrication of truly three-dimensional (3D) and large-scale metamaterials is needed to increase the degrees of freedom of the functionality for device level …

The Silver Lining: A Novel, Inkjet-Printed Mesh Coplanar-Slot Antenna For The Uhf Band, Anastasios C. Karles

Undergraduate Research Posters

The Federal Communications Commission (FCC) is opening up frequencies within the television range (400MHz to 700MHz) of the Ultra High Frequency (UHF) band for use in emerging technologies, such as cognitive radio networks and machine-to-machine communication. In order for manufacturers to produce affordable antennas that can be used in these emerging technologies, inexpensive antennas are required that meet these new spectrum needs. This paper presents a mesh coplanar-slot bowtie patch antenna fabricated using commercially available inkjet-printing technology. Two antennas were fabricated: a 27x21cm copper FR4 antenna with .25mm lines and a 27x21cm silver antenna with 2mm lines fabricated using inkjet-printing. …