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in creator/contributor: "Lowry, M"

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Characterization and Compensation of High Speed Digitizers

Increasingly, ADC technology is being pressed into service for single single-shot instrumentation applications that were formerly served by vacuum-tube based oscilloscopes and streak cameras. ADC technology, while convenient, suffers significant performance impairments. Thus, in these demanding applications, a quantitative and accurate representation of these impairments is critical to an understanding of measurement accuracy. We have developed a phase-plane behavioral model, implemented it in … more

Date: April 4, 2005

Creator: Fong, P; Teruya, A & Lowry, M

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ultrafast Radiation Detection by Modulation of an Optical Probe Beam

We describe a new class of radiation sensor that utilizes optical interferometry to measure radiation-induced changes in the optical refractive index of a semiconductor sensor medium. Radiation absorption in the sensor material produces a transient, non-equilibrium, electron-hole pair distribution that locally modifies the complex, optical refractive index of the sensor medium. Changes in the real (imaginary) part of the local refractive index produce a differential phase shift (absorption) of … more

Date: February 22, 2006

Creator: Vernon, S. P. & Lowry, M. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Probing the strange nature of the nucleon with phi photoproduction

The presence inside the nucleon of a significant component of strange-antistrange quark pairs has been invoked to explain a number of current puzzles in the low energy realm of QCD. The {sigma} term in {pi}N scattering is a venerable conundrum which can be explained with a 10%--20% admixture. The spin crisis brought on by the EMC result and follow on experiments was first interpreted as requiring a large strange content of s quarks whose spin helped cancel the contribution of the u and d quarks… more

Date: March 6, 1997

Creator: Lowry, M.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Long distance transmission of 15 Gb/s digital using subcarrier multiplexing and external modulation

This paper provides an overview of a high-speed link design using subcarrier multiplexing techniques with external modulators. Although we have few experimental results to data, we feel the techniques and technology described in this paper will enable the simultaneous transmission of multi-channel analog video and up to 15 Gb/s of digital data on a single wavelength. Furthermore, we show preliminary modeling that would indicate that at least four channels of 2.5 Gb/s can be sent over distances … more

Date: March 1, 1994

Creator: Hugenberg, K.; Lowry, M.; Beckedahl, D. & Blair, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gallium arsenide integrated optical devices for high-speed diagnostic systems

The design, fabrication, and evaluation of waveguide electro-optic modulators in gallium arsenide for application to high-speed diagnostic systems are discussed specifically. This paper is focused on high bandwidth, single event analog modulation, and radiation susceptibility of these devices.

Date: January 1, 1987

Creator: McWright, G.; Lowry, M.; Takeuchi, E.; Murphy, G.; Tindall, W.; Koo, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low-cost packaging of high-performance optoelectronic components

Optoelectronic component costs are often dominated by the costs of attaching fiber optic pigtails--especially for the case of single transverse mode devices. We present early results of our program in low-cost packaging. We are employing machine-vision controlled automated positioning and silicon microbench technology to reduce the costs of optoelectronic components. Our machine vision approach to automated positioning has already attained a positional accuracy of less than 5 microns in less th… more

Date: August 1, 1994

Creator: Lowry, M.; Lu, Shin-Yee; Pocha, M. & Strand, O. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radsensor: Optical Dielectric-Modulation Sensing of Ionizing Radiation for Diagnostics for Weapons Physics Ignition Experiments

The objective of this program is to investigate and develop a novel class of high speed single transient ionizing radiation detector technologies that will enable critical diagnostics for the Stockpile Stewardship Management Program (such as ignition and other experiments) that is currently lacking. The goal is to achieve temporal resolution in the {approx}100 fs to 1 ps range, provide adequate fidelity to accurately measure DT burn histories, and extrapolate these to probable impact on nuclear… more

Date: August 24, 2000

Creator: Lowry, M; Lee, H; Larson, M; Delgado, G & Thielen, P

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electro-optic transient imaging instrumentation development at Lawrence Livermore National Laboratory: Implications for SSC instrumentation development

Over the last decade, the underground weapons physics laboratories fielded by LLNL's Nuclear Test and Experimental Sciences (NTES) program have experienced marked change. This change is characterized by a phenomenal growth in the amount of data returned per event. These techniques have been developed as a result of the severe demands placed upon transient instrumentation by the physics requirements of our underground nuclear laboratories. The detector front-ends must quickly detect, process and… more

Date: December 1, 1990

Creator: Lowry, M.; Jacoby, B. & Schulte, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Characterization of lithium niobate electro-optic modulators at cryogenic temperatures

This paper reports on the operation of lithium niobate electro-optic waveguide modulators at temperatures down to 15{degrees}K. Commercial and laboratory fiber pigtailed devices have successfully been cooled without any increases in insertion loss from temperature induced stresses in device packaging. Three x-cut devices exhibited a linear increase in V{pi} voltage of 8%{plus_minus}1% when cooled from room temperature to {approximately} 20{degree}K. The broadband frequency response improved at … more

Date: January 1, 1994

Creator: Morse, J.; McCammon, K.; McConaghy, C.; Masquelier, D.; Garrett, H. & Lowry, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

White-light spectral analysis of lithium niobate waveguides

Optical channel waveguides in lithium niobate are a very useful technique for building a variety of integrated optical components such as modulators, splitters, and frequency doublers. In many of these applications, single mode performance is essential in order to achieve the desired device performance. Determination of single-mode operation can be complicated by the fact that a multimode guide can support lower order modes and can appear single mode if the launch conditions for the light into … more

Date: July 1, 1994

Creator: McConaghy, C. F.; Hugenberg, K. F.; Sweider, D.; Lowry, M. & Becker, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design and packaging aspects of microwave bandwidth lithium niobate modulators

Packaging of integrated optic modulators can be simplified if the electrodes are 50 ohms impedance. Recently built X-cut lithium niobate velocity matched modulators have a 50 ohm impedance. The interconnection of the modulators to external connectors by on-chip tapers is critical to there performance at frequencies in the 23 to 50 Ghz frequency range. The attachment of fibers to the modulators is being enhanced with work on a robotic machine that uses a combination of machine vision and active … more

Date: January 1, 1994

Creator: McConaghy, C. F.; Lu, S. Y.; Sargis, P.; Lowry, M. & Becker, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Integrated optical devices for photonics instrumentation systems

We discuss the design, fabrication, and evaluation of high speed integrated optical devices for application to photonics instrumentation systems. Specifically, we have demonstrated integrated optical devices with bandwidths in excess of 25 GHz and implemented these devices in single-shot, streak camera based recording schemes. 5 refs., 6 figs.

Date: January 1, 1990

Creator: McWright, G.M.; Lafaw, D.A.; Lowry, M. & Tindall, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Static and Time-Resolved 10-1000 ke V X-Ray Imaging Detector Options for NIF

High energy (> 10 keV) x-ray self-emission imaging and radiography will be essential components of many NIF High Energy Density Physics experiments. In preparation for such experiments, we have evaluated the pros and cons of various static (x-ray film, bare CCD, and scintillator + CCD) and time-resolved (streaked and gated) 10-1000 keV detectors.

Date: April 15, 2004

Creator: Landen, O; Bell, P; McDonald, J; Park, H; Weber, F; Moody, J et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

All-optical modulation in gallium arsenide integrated optical waveguides

We have investigated all-optical modulators in gallium arsenide integrated optical waveguides; these modulators use electron-hole pair generation to alter the propagation characteristics of a guided light beam. 6 refs., 6 figs.

Date: January 27, 1988

Creator: McWright, G.; Ross, B.; Guthreau, W.; Lafaw, D.; Lowry, M. & Tindall, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modeling a distributed spatial filter low-noise semiconductor optical amplifier

We show using a beam propagation technique how periodic spatial filtering can reduce amplified spontaneous emission noise in a semiconductor optical amplifier.

Date: December 1, 1997

Creator: Ratowsky, R. P.; Dijaili, S.; Kallman, J. S.; Feit, M. D.; Walker, J.; Goward, W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Overview of photonics research at Lawrence Livermore National Laboratory

Much of Lawrence Livermore National Laboratory`s (LLNL) expertise in photonics was acquired in the execution of the Nuclear Testing mission. As LLNL refocuses its resources into areas that have dual benefit for the nation, their photonics program is beginning to apply these unique capabilities to key national issues involving high-speed communications, while retaining the expertise to apply the technology to defense missions. Much of the exciting work being done at LLNL will have applications i… more

Date: May 1, 1994

Creator: Roeske, F.; Deri, B.; Dijaili, S.; Lee, H.; Lowry, M.; McConaghy, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance characterization of photonic links in cryogenic environments for advanced signal processing applications. Revision 1

Low temperature experiments have been conducted to characterize the performance of high speed photodetectors and LiNbO{sub 3} optical modulators in cryogenic environments down to 4.2 K. Metal-semiconductor-metal (MSM) photodiodes fabricated from GaAs and InGaAs have been characterized. Results demonstrate that both the responsivity and bandwidth depend on temperature. Specific modulator parameters quantified at cryogenic temperatures include bandwidth, V{pi} (half wave voltage), optical loss an… more

Date: January 1, 1994

Creator: McCammon, K.; Morse, J.; Masquelier, D.; McConaghey, C.; Garrett, H.; Hugenberg, K. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

RadTracker: Optical Imaging of High Energy Radiation Tracks

This project examined the possibility of extending the recently demonstrated radoptic detection approach to gamma imaging. Model simulations of the light scattering process predicted that expected signal levels were small and likely below the detection limit of large area, room-temperature detectors. A series of experiments using pulsed x-ray excitation, modulated gamma excitation and optical pump-probe methods confirmed those theoretical predictions. At present the technique does not appear to… more

Date: March 2, 2007

Creator: Vernon, S. P.; Lowry, M. E.; Comaskey, B. J.; Heebner, J. E.; Kallman, J. S. & Richards, J. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fiber optic transceiver for interfacing digital superconducting electronics

Low temperature experiments have been conducted in order to characterize the performance of high speed photodetectors and LiNbO{sub 3} optical modulators in cryogenic environments down to 4.2{degree}K. Specific parameters quantified from this study include bandwidth, responsivity, V{pi} (half wave voltage), optical loss and package stability. Metal-semiconductor-metal (MSM) photodiodes fabricated from GaAs and InGaAs have been characterized. Results demonstrate that both the responsivity and ba… more

Date: March 1, 1994

Creator: McCammon, K.; Morse, J.; Masquelier, D.; McConaghey, C.; Garrett, H.; Hugenberg, K. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Application of optical interconnect technology at Lawrence Livermore National Laboratory

Optical interconnects will be required to meet the information bandwidth requirements of future communication and computing applications. At Lawrence Livermore National Laboratory, the authors are involved in applying optical interconnect technologies in two distinct application areas: Multi-Gigabit/sec Computer Backplanes and Gigabit/sec Wide Area Networking using Wavelength Division Multiplexing. In this paper, the authors discuss their efforts to integrate optical interconnect technologies i… more

Date: August 10, 1995

Creator: Haigh, R. E.; Lowry, M. E.; McCammon, K.; Hills, R.; Mitchell, R. & Sweider, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photonic doppler velocimetry

We are developing a novel fiber-optic approach to laser Doppler velocimetry as a diagnostic for high explosives tests. Using hardware that was originally developed for the telecommunications industry, we are able to measure surface velocities ranging from centimeters per second to kilometers per second. Laboratory measurements and field trials have shown excellent agreement with other diagnostics.

Date: January 1, 1999

Creator: Lowry, M. E.; Molau, N. E.; Sargis, P. D.; Strand, O. T. & Sweider, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Radoptic x-ray detection with picosecond resolution

No Description Available.

Date: July 25, 2011

Creator: Lowry, M. E.; Vernon, S. P.; Steele, P. T.; Bennett, C. V.; Hernandez, V. J.; Moran, B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

LDRD final report: photonic analog-to-digital converter (ADC) technology

We report on an LDRD seed program of novel technology development (started by an FY98 Engineering Tech-base project) that will enable extremely high-fidelity analog-to-digital converters for a variety of national security missions. High speed (l0+ GS/s ), high precision (l0+ bits) ADC technology requires extremely short aperture times ({approx}1ps ) with very low jitter requirements (sub 10fs ). These fundamental requirements, along with other technological barriers, are difficult to realize wi… more

Date: February 18, 1999

Creator: Bowers, M; Deri, B; Haigh, R; Lowry, M; Sargis, P; Stafford, R et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Automated fiber pigtailing technology

The high cost of optoelectronic (OE) devices is due mainly to the labor-intensive packaging process. Manually pigtailing such devices as single-mode laser diodes and modulators is very time consuming with poor quality control. The Photonics Program and the Engineering Research Division at LLNL are addressing several issues associated with automatically packaging OE devices. A furry automated system must include high-precision fiber alignment, fiber attachment techniques, in-situ quality control… more

Date: February 1, 1994

Creator: Strand, O. T.; Lowry, M. E.; Lu, S. Y.; Nelson, D. C.; Nikkel, D. J.; Pocha, M. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department