Exploration of Novel Applications for Optical Communications using Silicon Nanophotonics

Silicon photonics is considered to have the potential to enable future communication systems with optical input-outputs to circumvent the shortcomings of electronics. Today silicon is the material of choice for photonic and optoelectronic circuits, mainly due to its excellent material properties, established processing technology, low-cost, compact device footprint, and high-density integration. From sensing and detection to computing and communications, silicon photonics has advanced remarkably in the last couple of decades and found numerous applications. This thesis work focusses on three novel applications of silicon photonics for optical communications. The first application is the design and demonstration of a differential phase shift keying (DPSK) demodulator circuit using a ring resonator. DPSK-based transceivers are being actively considered for short-haul optical communication systems due to their advantages in terms of high extinction ratio, dispersion tolerance, and improved sensitivity. The ring resonator utilizes the concept of coherent perfect absorption and results into a compact demodulator circuit that can be easily integrated into an all-optical system. The next application involves a nonlinear optical process, namely, four wave mixing (FWM) inside a silicon nanowire. For FWM to occur efficiently, phase matching between the real propagation constants of all the frequency components is a key requirement. However, this condition cannot be easily satisfied in integrated optics semiconductor platforms. We propose an altogether new approach to achieve signal gain within the context of non-Hermitian photonics and parity-time (PT) symmetry and show that the phase matching criterion is not necessary to achieve efficient nonlinear interactions. Instead by introducing losses only to the idler components while leaving the pump and signal waves intact, we analyze a coupled-wave system of silicon nanowires using finite difference time domain technique and find that signal gain is indeed possible in such a system, irrespective of the fulfillment of the phase-matching condition. The final application of silicon photonics in this thesis is the engineering of zero group velocity dispersion (GVD) point in the C-band of communication channel. The problem of pulse broadening due to chromatic dispersion is becoming an increasingly important factor for signal degradation. We propose a hybrid silicon/plasmonic waveguide that can change the zero-GVD point by altering the geometry and material of the waveguide components. In addition, such hybrid system also has the potential to transmit both optical and electronic signals along the same circuitry

Dedication to Professor Michael Tribelsky

Professor Tribelsky's accomplishments are highly appreciated by the international community. The best indications of this are the high citation rates of his publications, and the numerous awards and titles he has received. He has made numerous fundamental contributions to an extremely broad area of physics and mathematics, including (but not limited to) quantum solid-state physics, various problems in light–matter interaction, liquid crystals, physical hydrodynamics, nonlinear waves, pattern formation in nonequilibrium systems and transition to chaos, bifurcation and probability theory, and even predictions of the dynamics of actual market prices. This book presents several extensions of his results, based on his inspiring publications

Energy. A continuing bibliography with indexes, issue 36, January 1983

This bibliography lists 1297 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1982 through December 31, 1982

Integrated design approach for responsive solar-shadings in double skin facades in hot arid climate

Ph. D. Thesis.To deliver climate adaptive architecture, current trends in architecture are directed towards dynamic and responsive building skins. ‘Responsive building skin’ is used to describe the ability of building envelopes to adapt in real time in response to external environmental conditions. Recent attention has focused on ‘soft robotics’ approach which uses soft and/or extensible materials to deform with muscle‐like actuation, mimicking biological systems. Material embedded actuation can autonomously alter shading systems’ morphology stimulated by external environmental conditions. Passively thermally‐activated shading systems offer responsive actuation by solar‐radiation and stratified hot air in a double skin façade (DSF) without recourse to energy consuming systems. This research identifies the intersection between bio‐inspiration, folding principles and smart materials to integrate the underlying mechanisms in responsive solar‐shading systems and assesses their environmental performance. The thesis proposes an interdisciplinary mixed methodology linking hands‐on experimentation with environmental performance simulation of responsive building skins. ‘Practice‐led approach’ is used to explore the design potential of responsive systems using smart materials. ‘Computational Fluid Dynamics’ (CFD) numerical methods are used to measure the impact of responsive solar‐shading systems on multiple environmental factors in a DSF cavity. This helps the design decisions, selection and customisation of smart materials. Hands‐on experimentation is used to explore various prototypes, leading to the selection of a folded prototype, to be simulated for environmental performance. Solar‐shading systems are tested within a DSF, in an hot arid climate. Flat and folded solar‐shading devices are installed in a DSF cavity with three aperture sizes (30%, 50% & 70%) to represent the responsive system states. Point‐in‐time simulations are carried at 9:00 am, 12:00 pm and 15:00 pm in peak summer and winter day. The developed analytical design framework presents different design parameters for responsive solar‐shading systems to guide decision‐making in research of climate actuated smart shading systems. Keywords: Responsive skins, Adaptive facades, Soft robotics, Bio‐inspiration, Origami, Deployable structures, Actuation, Smart materials, Shape memory alloys, Double skin facades, Energy efficiency, Digital simulation, CFD Modelling

The Second Conference on Lunar Bases and Space Activities of the 21st Century, volume 1

These papers comprise a peer-review selection of presentations by authors from NASA, LPI industry, and academia at the Second Conference (April 1988) on Lunar Bases and Space Activities of the 21st Century, sponsored by the NASA Office of Exploration and the Lunar Planetary Institute. These papers go into more technical depth than did those published from the first NASA-sponsored symposium on the topic, held in 1984. Session topics covered by this volume include (1) design and operation of transportation systems to, in orbit around, and on the Moon, (2) lunar base site selection, (3) design, architecture, construction, and operation of lunar bases and human habitats, and (4) lunar-based scientific research and experimentation in astronomy, exobiology, and lunar geology

Proceedings of the Seventh Annual Summer Conference. NASA/USRA: University Advanced Design Program

The Advanced Design Program (ADP) is a unique program that brings together students and faculty from U.S. engineering schools with engineers from the NASA centers through integration of current and future NASA space and aeronautics projects into university engineering design curriculum. The Advanced Space Design Program study topics cover a broad range of projects that could be undertaken during a 20-30 year period beginning with the deployment of the Space Station Freedom. The Advanced Aeronautics Design Program study topics typically focus on nearer-term projects of interest to NASA, covering from small, slow-speed vehicles through large, supersonic passenger transports and on through hypersonic research vehicles. Student work accomplished during the 1990-91 academic year and reported at the 7th Annual Summer Conference is presented