Silicon-organic hybrid photonics: Overview of recent advances, electro-optical effects and CMOS-integration concepts

In recent decades, much research effort has been invested in the development of photonic integrated circuits, and silicon-on-insulator technology has been established as a reliable platform for highly scalable silicon-based electro-optical modulators. However, the performance of such devices is restricted by the inherent material properties of silicon. An approach to overcoming these deficiencies is to integrate organic materials with exceptionally high optical nonlinearities into a silicon-on-insulator photonic platform. Silicon–organic hybrid photonics has been shown to overcome the drawbacks of silicon-based modulators in terms of operating speed, bandwidth, and energy consumption. This work reviews recent advances in silicon–organic hybrid photonics and covers the latest improvements to single components and device concepts. Special emphasis is given to the in-device performance of novel electro-optical polymers and the use of different electro-optical effects, such as the linear and quadratic electro-optical effect, as well as the electric-field-induced linear electro-optical effect. Finally, the inherent challenges of implementing non-linear optical polymers on a silicon photonic platform are discussed and a perspective for future directions is given

Piezoelectric Materials

The science and technology in the area of piezoelectric ceramics are extremely progressing, especially the materials research, measurement technique, theory and applications, and furthermore, demanded to fit social technical requests such as environmental problems. While they had been concentrated on piezoelectric ceramics composed of lead-containing compositions, such as lead zirconate titanate (PZT) and lead titanate, at the beginning because of the high piezoelectricity, recently lead water pollution by soluble PZT of our environment must be considered. Therefore, different new compositions of lead-free ceramics in order to replace PZT are needed. Until now, there have been many studies on lead-free ceramics looking for new morphotropic phase boundaries, ceramic microstructure control to realize high ceramic density, including composites and texture developments, and applications to new evaluation techniques to search for high piezoelectricity. The purpose of this book is focused on the latest reports in piezoelectric materials such as lead-free ceramics, single crystals, and thin films from viewpoints of piezoelectric materials, piezoelectric science, and piezoelectric applications

Noise Suppression in OCDMA Networks using Nonlinear Optical Devices

Optical code division multiple access (OCDMA) is a multiplexing technique that has a number of inherent advantages that make it suitable for use in passive optical networks, such as allowing subscribers to transmit information in an asynchronous fashion over a single optical fibre. This form of multiplexing can provide a higher degree of flexibility and simplicity in comparison to other techniques. However, due to the asynchronous nature of transmission, OCDMA networks suffer from multiple access interference (MAI) and optical beat noise which severely impairs system performance. A number of solutions have been proposed to mitigate these noise sources. Increasing the optical code lengths used can reduce the level of optical beat noise, however this is generally at the expense of transmission speed and increased transmitter complexity. MAI suppression can be achieved through the use fibre-based nonlinear thresholders or optical time-gating. One problem with these solutions is the requirement of long lengths of nonlinear fibre that are susceptible to changes in environmental conditions. Therefore, this thesis focuses on the development and testing of a nonlinear optical receiver based on semiconductor devices for the suppression of noise in OCDMA systems. The nonlinear optical process of two-photon absorption (TPA) in a commercially available 1.3 micron Fabry-P´erot laser is investigated as a method for optical thresholding in an OCDMA system. It is shown that the use of a saturable absorber (SA) directly before the TPA-based detector can provide additional suppression of MAI noise. However, the level of beat noise that is present on the optical signal can be increased due to the nonlinear responses of both devices. As a result, a gain-saturated semiconductor optical amplifier (SOA) is demonstrated as a method for the reduction of optical beat noise. It is shown that error-free performance can be achieved in an optical testbed designed to simulate an OCDMA system using an SA-SOA-TPA-based receiver. The performance improvement due to the suppression of MAI and beat noise using an SA-SOA receiver is examined in relation to a current fibre-based thresholding technique; a Mamyshev filter. It is shown that the SA-SOA receiver can offer a similar level of improvement when compared to the performance of a Mamyshev filter

Project Cyclops: a Design Study of a System for Detecting Extraterrestrial Intelligent Life

The requirements in hardware, manpower, time and funding to conduct a realistic effort aimed at detecting the existence of extraterrestrial intelligent life are examined. The methods used are limited to present or near term future state-of-the-art techniques. Subjects discussed include: (1) possible methods of contact, (2) communication by electromagnetic waves, (3) antenna array and system facilities, (4) antenna elements, (5) signal processing, (6) search strategy, and (7) radio and radar astronomy

The Q(weak) experimental apparatus

The Jefferson Lab experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise (e) over right arrowp asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. The experiment employed 180 mu A of 89% longitudinally polarized electrons whose helicity was reversed 960 times per second. The electrons were accelerated to 1.16 GeV and directed to a beamline with extensive instrumentation to measure helicity-correlated beam properties that can induce false asymmetries. Muller and Compton polarimetry were used to measure the electron beam polarization to better than 1%. The electron beam was incident on a 34.4 cm liquid hydrogen target. After passing through a triple collimator system, scattered electrons between 5.8 degrees and 11.6 degrees were bent in the toroidal magnetic field of a resistive copper-coil magnet. The electrons inside this acceptance were focused onto eight fused silica Cherenkov detectors arrayed symmetrically around the beam axis. A total scattered electron rate of about 7 GHz was incident on the detector array. The detectors were read out in integrating mode by custom-built low-noise pre-amplifiers and 18-bit sampling ADC modules. The momentum transfer Q(2)=0.025 GeV2 was determined using dedicated low-current (similar to 100 pA) measurements with a set of drift chambers before (and a set of drift chambers and trigger scintillation counters after) the toroidal magnet. (C) 2015 Elsevier B.V All rights reserved

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented

Doppler Encoded Excitation Patterning (DEEP) Microscopy

Traditional optical imaging systems rely on lenses and spatially-resolved detection to probe distinct locations on the object. We develop a novel computational approach to 2D and 3D imaging that instead measures the object\u27s spatial Fourier transform using a single-element detector and without requiring precision optics. This wide-field technique can be used to image biological and synthetic structures in fluoresced or scattered light using coherent or broadband illumination. It employs dynamic structured illumination, acousto-optics, RF electronics, and tomographic algorithms to circumvent several trade-offs in conventional imaging, such as the dependence of the optical transfer function on the imaging lenses and the coupling of resolution and depth of field. We use Fourier optics concepts to derive the dynamic optical transfer function, evaluate different Fourier sampling strategies, and investigate and compare tomographic algorithms for 2D and 3D image synthesis. We also develop conceptual and analytical models to describe imaging of fluorescent as well as amplitude and phase scattering objects, the effects of broadband and spatially-incoherent illumination, and nonlinear wide-field super-resolution imaging. We consider sources of noise, analyze and simulate SNR behavior for several types of noise and Fourier sampling strategies, and compare the sensitivity of the technique to conventional imaging. We describe several experimental proof-of-concept systems and present two-dimensional high-resolution tomographic image reconstructions in both scattered and fluoresced light demonstrating a thousandfold improvement in the depth of field compared to conventional lens-based microscopy. Finally, we explore approaches for high-speed Fourier sampling and propose several related sensing techniques, including wide-field fluorescence imaging in scattering media

Hydrogen Research at Florida Universities

This final report describes the R&D activities and projects conducted for NASA under the 6-year NASA Hydrogen Research at Florida Universities grant program. Contained within this report are summaries of the overall activities, one-page description of all the reports funded under this program and all of the individual reports from each of the 29 projects supported by the effort. The R&D activities cover hydrogen technologies related to production, cryogenics, sensors, storage, separation processes, fuel cells, resource assessments and education. In the span of 6 years, the NASA Hydrogen Research at Florida Universities program funded a total of 44 individual university projects, and employed more than 100 faculty and over 100 graduate research students in the six participating universities. Researchers involved in this program have filed more than 20 patents in all hydrogen technology areas and put out over 220 technical publications in the last 2 years alone. This 6 year hydrogen research program was conducted by a consortium of six Florida universities: Florida International University (FIU) in Miami, Florida State University (FSU) and Florida A&M University (FAMU) in Tallahassee, University of Central Florida (UCF) in Orlando, University of South Florida (USF) in Tampa, and University of Florida (UF) in Gainesville. The Florida Solar Energy Center (FSEC) of the University of Central Florida managed the research activities of all consortium member universities except those at the University of Florida. This report does not include any of the programs or activities conducted at the University of Florida, but can be found in NASA/CR-2008-215440-PART 1-3