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Measurement of Optical Fiber Bandwidth in the Frequency Domain

Description: Abstract: The design, evaluation, and performance of a system for determining the magnitude of the transfer function (hence, the bandwidth) of a multimode optical fiber are presented. The system operates to about 1450 MHz using a tracking generator/spectrum analyzer combination for narrowband detection. It is constructed, almost entirely, from commercially available components. The system is less complex and easier to use than an equivalent time domain system and the measurement precision is comparable. Background information on time and frequency domain specifications, fiber bandwidth limitations, and alternate frequency domain techniques is also presented.
Date: September 1981
Creator: Day, G. W.
Partner: UNT Libraries Government Documents Department

The Characterization of Optical Fiber Waveguides: A Bibliography with Abstracts, 1970-1980

Description: Abstract: This bibliography contains approximately 450 citations of papers concerning the characterization of optical fiber waveguides. Papers from scientific journals, trade journals and conferences are included along with book chapters. The citations of organized by parameter measured and measurement method. Where published abstracts are available they are included.
Date: June 1981
Creator: Day, G. W.
Partner: UNT Libraries Government Documents Department

Fault warning device using fiber-optic partial discharge sensor for prevention of destructive arc faults in metal-clad electrical switchgear and bus. [Semiannual report, May 1 - October 31, 1999]

Description: Progress made and problems encountered so far is discussed with reference to the Statement of Work which was submitted as part of the grant application. This work plan breaks down the project into fourteen numbered tasks grouped into three phases: Development of Improved Sensor Materials (Phase 1), Laboratory Testing of Improved Prototype on 15 kV Switchgear (Phase 2),and Field Testing of Beta Prototype and Start of Commercialization (Phase 3).
Date: December 2, 1999
Creator: Forsyth, Keith W.
Partner: UNT Libraries Government Documents Department

Photonic Power Delivery Through Optical Fiber Using Very High Power Laser Diode Arrays

Description: Described is a system that will provide isolated electric power for a circuit that drives the core reset of a pulsed power modulator. This can be accomplished by coupling light from a number of diode laser bars to bundles of 200 um multimode optical fibers. This is then coupled to photo-voltaic power converters that will deliver 16 V 29mA of electricity from 1 watt of optical power. Spot size at the bundle face is a Gausian ellipse with a major axis of 1.4 mm radius and a minor axis of four bundles of 12 fibers generating a total of 24 W of electrical power. Various schemes are used to maximize coupling into the optical filber while limiting the number of optical components, and comparing components such as fresnel and aspheric lenses and lens ducts for effectiveness and cost. This will provide a completely isolated low power source for high voltage, high current environments where tradional isolation techniques yield inadequate isolation or prove too cumbersome.
Date: May 1, 1999
Creator: Heino, Matthew & Saethre, Robert
Partner: UNT Libraries Government Documents Department

A FEMTOSECOND-LEVEL FIBER-OPTICS TIMING DISTRIBUTION SYSTEM USING FREQUENCY-OFFSET INTERFEROMETRY

Description: An optical fiber-based frequency and timing distribution system based on the principle of heterodyne interferometry has been in development at LBNL for several years. The fiber drift corrector has evolved from an RF-based to an optical-based system, from mechanical correctors (piezo and optical trombone) to fully electronic, and the electronics from analog to fully digital, all using inexpensive off-the-shelf commodity fiber components. Short-term optical phase jitter and long-term phase drift are both in the femtosecond range over distribution paths of 2 km or more.
Date: October 17, 2009
Creator: Staples, J.W.; Byrd, J.; Doolittle, L.; Huang, G. & Wilcox, R.
Partner: UNT Libraries Government Documents Department

Compact, low-crosstalk, WDM filter elements for multimode ribbon fiber data links

Description: We have been developing the optical components for a source-routed wavelength division multiplexed (WDM) computer interconnect fabric that uses multi-mode fiber ribbon cable as the transmission medium. We are developing wavelength selectable VCSEL transmitters, interference filters, and a compact broadcast element. Here we report on key results from our interference filter development activities. Our WDM filter approach is based upon post-market machining of the commercially available molded plastic �MT� fiber ribbon connector. We use III-IV semiconductors grown by MBE or MOCVD as the filter materials. The high indices of our thin film materials enable us to use multimode fiber and maintain narrow passbands without the need for micro-optics. We have fabricated both 2-port and 3-port devices based upon this approach. Our current work focuses on 2-port WDM filters suitable for a broadcast and select architecture. Our single-cavity Fabry- Perot (FP) filters have demonstrated insertion losses of < 2 dB for 4 nm passbands. The maximum crosstalk suppression for the single-cavity FP filters is 18dB To improve crosstalk suppression beyond that attainable with the Lorentzian lineshapes of the single-cavity FP we have investigated some multiple-cavity Fabry-Perot (MC-FP) designs which have a spectral response with a flatter top and sharper passband edges. Filter passband edge sharpness can be quantified by the ratio of the filter 3 dB bandwidth to 18 dB bandwidth This ratio is 0.48 for our multi-cavity filter, three times sharper than the single-cavity FP devices. This device provides a 5 nm tolerance window for component wavelength variations (at 1 dB excess loss) and is suitable for 10 nm channel spacing with 23 dB crosstalk suppression between adjacent channels. The average insertion loss for the MC-l? devices is 1.6 dB. (Average of insertion losses for the 12 fibers in a filter module.) Our current MC-FP filters have a 3-dB width ...
Date: January 1, 1999
Creator: Deri, R J; Emanuel, M A; Garrett, H H; Krol, D M; Larson, M Pocha, M D; Lowry, M E et al.
Partner: UNT Libraries Government Documents Department

Propagation of 2.5 Gb/s Asynchronous, Concurrent, Optical CDMA Signals Through a 214 Kilometer Fiber Optic Link

Description: The propagation of optical Code Division Multiple Access (CDMA) signals was studied by computer simulation. Group velocity dispersion produces the worst impairment. With dispersion management, the decoder successfully recovers the signals, even in the presence of severe multi-access interference.
Date: March 16, 2000
Creator: Mendez, A.J.; Feng, H.X.C.; Heritage, J.P.; Morookian, J. & Gagliardi, R.M.
Partner: UNT Libraries Government Documents Department

A deterministic, gigabit serial timing, synchronization and data link for the RHIC LLRF

Description: A critical capability of the new RHIC low level rf (LLRF) system is the ability to synchronize signals across multiple locations. The 'Update Link' provides this functionality. The 'Update Link' is a deterministic serial data link based on the Xilinx RocketIO protocol that is broadcast over fiber optic cable at 1 gigabit per second (Gbps). The link provides timing events and data packets as well as time stamp information for synchronizing diagnostic data from multiple sources. The new RHIC LLRF was designed to be a flexible, modular system. The system is constructed of numerous independent RF Controller chassis. To provide synchronization among all of these chassis, the Update Link system was designed. The Update Link system provides a low latency, deterministic data path to broadcast information to all receivers in the system. The Update Link system is based on a central hub, the Update Link Master (ULM), which generates the data stream that is distributed via fiber optic links. Downstream chassis have non-deterministic connections back to the ULM that allow any chassis to provide data that is broadcast globally.
Date: March 28, 2011
Creator: Hayes, T.; Smith, K.S. & Severino, F.
Partner: UNT Libraries Government Documents Department

Optical Sensor Technology Development and Deployment

Description: The objectives of this ESP (Enhanced Surveillance) project are to evaluate sensor performance for future aging studies of materials, components and weapon systems. The goal of this project is to provide analysis capability to experimentally identify and characterize the aging mechanisms and kinetics of Core Stack Assembly (CSA) materials. The work on fiber optic light sources, hermetic sealing of fiber optics, fiber optic hydrogen sensors, and detection systems will be discussed.
Date: January 24, 2005
Creator: Parker, B. G.
Partner: UNT Libraries Government Documents Department

Shortwave Spectroradiometer (SWS) Handbook

Description: The Shortwave Spectroradiometer (SWS), measures the absolute visible and near infrared spectralradiance (units of watts per meter square per nanometer per steradian) of the zenith directly above the instrument. The SWS is a moderate resolution sensor comprised of two Zeiss spectrometers (MMS 1 NIR enhanced and NIR-PGS 2.2) for visible and near-infrared detection in the wavelength range 350 – 2170 nm. The sampling frequency is 1 Hz. The spectral resolution is 8 nm for the MMS 1 NIR and 12 nm for the NIR-PGS 2.2. The light collector is a narrow field of view (1.4°) collimator at the front end of a high-grade custom-made fiber optic bundle. The SWS does daily daytime measurements. The SWS is located in a darkroom, constructed by Southern Great Plains (SGP) site personnel within the optical trailer, to permit calibrations to be conducted without the necessity of moving the instrument to a different location. Calibrations are performed at regularly scheduled times using the ARM 12” integrating sphere.
Date: November 1, 2006
Creator: Pilewskie, P & Pommier, J
Partner: UNT Libraries Government Documents Department

Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

Description: New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.
Date: January 2, 2010
Creator: Wilcox, R.; Byrd, J. M.; Doolittle, L.; Huang, G. & Staples, J. W.
Partner: UNT Libraries Government Documents Department

Locking Lasers to RF in an Ultra Fast FEL

Description: Using a novel, phase-stabilized RF-over-fiber scheme, they transmit 3GHz over 300m with 27fs RMS error in 250kHz bandwidth over 12 hours, and phase lock a laser to enable ultrafast pump-probe experiments. Free-electron lasers (FELs) are capable of producing short-duration (&lt; 10fs), high-energy X-ray pulses for a range of scientific applications. The recently activated Linac Coherent Light Source (LCLS) FEL facility at SLAC will support experiments which require synchronized light pulses for pump-probe schemes. They developed and operated a fiber optic RF transmission system to synchronize lasers to the emitted X-ray pulses, which was used to enable the first pump-probe experiments at the LCLS.
Date: January 2, 2010
Creator: Wilcox, R.; Huang, G.; Doolittle, L.; White, W.; Frisch, J. & Coffee, R.
Partner: UNT Libraries Government Documents Department

Propagation or failure of detonation across an air gap in an LX-17 column: continuous time-dependent detonation or shock speed using the Embedded Fiber Optic (EFO) technique

Description: The detailed history of the shock/detonation wave propagation after crossing a room-temperature-room-pressure (RTP) air gap between a 25.4 mm diameter LX-17 donor column and a 25.4 mm diameter by 25.4 mm long LX-17 acceptor pellet is investigated for three different gap widths (3.07, 2.08, and 0.00 mm) using the Embedded Fiber Optic (EFO) technique. The 2.08 mm gap propagated and the 3.07 mm gap failed and this can be seen clearly and unambiguously in the EFO data even though the 25.4 mm-long acceptor pellet would be considered quite short for a determination by more traditional means such as pins.
Date: January 16, 2008
Creator: Hare, D E; Chandler, J B; Compton, S M; Garza, R G; Grimsley, D A; Hernandez, A et al.
Partner: UNT Libraries Government Documents Department

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

Description: A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. Due to the improved mechanical properties of this approach high temperature sensor measurements were performed up to 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.
Date: September 30, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; Osborn, D. J. & Zhang, Po
Partner: UNT Libraries Government Documents Department

Development of Pulse Position Modulation/Optical CDMA (PPM/O-CDMA) for Gb/s Fiber Optic Networking

Description: Pulse position modulation (PPM) in lasercom systems is known to provide potential advantages over other modulation schemes. [1]. In PPM, a periodic time frame is established and data is transmitted by placing a pulse in any one of several subintervals (or ''slots'') within each frame. In PPM/O-CDMA all users use the same frame structure and each transmits its unique address code in place of the PPM pulse. The advantage of PPM as a pulsed signal format is that (1) a single pulse can transmit multiple bits during each frame; (2) decoding (determining which subinterval contains the pulse) is by comparison rather than threshold tests (as in on-off-keying); (3) each user transmits in only a small fraction of the frame, hence the multi-access interference (MAI) of any user statistically spreads over the entire frame time, reducing the chance of overlap with any other user; and (4) under an average power constraint, increasing frame time increases the peak pulse power (i.e., PPM trades average power for peak power). The most straightforward approach to implementing PPM/O-CDMA data modulator inserts the PPM pulse modulation first, then imposes the O-CDMA coding. A pulsed PPM modulator converts bits (words) into pulse positions. In the case of wavelength/time (W/T) matrix codes, multi-wavelength pulses are generated at the beginning of each frame, at the frame rate. For M-ary PPM, a block of k bits represents M = 2{sup k} unique interval positions in the frame corresponding to M-l specific time delays (the zero delay is also a position). PPM modulation is achieved by shifting the initial pulse into an interval position with delay D(i) (i=0,1,2,..,M-1). The location of a pulse position (selection of a delay) therefore identifies a unique k-bit word in the frame. At the receiver, determining which delay occurs relative to the frame start time decodes ...
Date: May 25, 2006
Creator: Mendez, A J; Hernandez, V J; Gagliardi, R M; Bennett, C V & Lennon, W J
Partner: UNT Libraries Government Documents Department

Near-Field Magneto-Optical Microscope

Description: A device and method for mapping magnetic fields of a sample at a resolution less than the wavelength of light without altering the magnetic field of the sample is disclosed. A device having a tapered end portion with a magneto-optically active particle positioned at the distal end thereof in communication with a fiber optic for transferring incoming linearly polarized light from a source thereof to the particle and for transferring reflected light from the particle is provided. The fiber optic has a reflective material trapping light within the fiber optic and in communication with a light detector for determining the polarization of light reflected from the particle as a function of the strength and direction of the magnetic field of the sample. Linearly polarized light from the source thereof transferred to the particle positioned proximate the sample is affected by the magnetic field of the sample sensed by the particle such that the difference in polarization of light entering and leaving the particle is due to the magnetic field of the sample. Relative movement between the particle and sample enables mapping.
Date: December 6, 2005
Creator: Vlasko-Vlasov, Vitalii; Welp, Ulrich & and Crabtree, George W.
Partner: UNT Libraries Government Documents Department

Radio Frequency Notch Filter Utilizing Fiber Optic Laser Diode Delay Line

Description: A wide band, laser-diode/fiber-optic transmission line (FOL) has been developed which represents a potentially useful stochastic cooling notch filter element. Because of its small size and lack of need for sophisticated support equipment the FOL presents a viable alternative to both conventional and super conducting coaxial line notch filters. This note summarizes the characteristics of the FOL and of notch filter performance achieved with its use.
Date: April 1, 1985
Creator: Konecny, R.
Partner: UNT Libraries Government Documents Department

Sapphire Fiber Optics Sensors for Engine Test Instrumentation

Description: This document is the final report for the Cooperative Research and Development Agreement (CRADA) between UT-Battelle and Prime Photonics, Inc. The purpose of this CRADA was to improve the properties of single crystal sapphire optical fibers for sensor applications. A reactive coating process was developed to form a magnesium aluminate spinel cladding on sapphire optical fibers. The resulting clad fiber had a numerical aperture, NA, of 0.09 as compared with 0.83 for the unclad fiber, dramatically enhancing its usefulness for sensor applications. Because the process allows one to control the diameter of the sapphire core within the fiber, it may be possible using this technology to develop waveguides that approach single-mode transmission character.
Date: September 19, 2003
Creator: Janney, MA
Partner: UNT Libraries Government Documents Department

Solids Fraction Measurement with a Reflective Fiber Optic Probe

Description: A method has been developed to extract solids fraction information from a reflective fiber optic probe. The commercially available reflective fiber optic probe was designed to measure axial particle velocity (both up and down directions). However, the reflected light intensity measured is related to particle size and particle concentration. A light reflection model is used to relate the reflected light intensity to solids fraction. In this model we assume that the reflected light intensity is a fixed fraction, K1, of the total light intensity lost in penetration of a solid layer. Also, the solids fraction is related to particle concentration, N, in the light path, by N = K2 (1- ε), where (1-ε) is the solids fraction. The parameters K1 and K2 are determined through a calibration and curve fitting procedure. This paper describes this procedure and the steps taken to derive the values of K1 and K2. It is proposed that the reflective fiber optic can be used for real time measurement of solids fraction in a circulating fluid bed.
Date: November 1, 2006
Creator: Seachman, S.M.; Yue, P.C.; Ludlow, J.C. & Shadle, L.J.
Partner: UNT Libraries Government Documents Department