U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications

NIST Authors in Bold

Displaying 32551 - 32575 of 73929

Electrical Characterization of Self-Assembled Monolayers

May 30, 2007
Author(s)
Wenyong Wang, Takhee Lee, Mark Reed
Electrical characterization of alkanethiol self-assembled monolayers (SAMs) has been performed using a nanometer-scale device structure. Temperature-variable current-voltage measurement is carried out to distinguish between different conduction mechanisms

A Theoretical Analysis of Frequency Uncertainty

May 29, 2007
Author(s)
Gianna Panfilo, Thomas E. Parker
In this work we present a preliminary study for the determination of the uncertainty on the frequency in the time measurement. The first part of this paper is dedicated to the theoretical study of the frequency uncertainty applying the law of the

Active Vibration-induced PM Noise Control in Optical Fibers: Preliminary Studies

May 29, 2007
Author(s)
David A. Howe, Archita Hati, Craig Nelson, Jennifer A. Taylor, Neil Ashby
Vibration causes mechanical distortions in fiber-optic transmission lines that induce time (phase) fluctuations. RF systems are increasingly using optical fibers in various ways and must occasionally operate in environments with acoustic and structure-born

Experimental Analysis of Frequency Transfer Uncertainty

May 29, 2007
Author(s)
Thomas E. Parker, Gianna Panfilo
An experimental analysis of frequency transfer uncertainty is carried out. In situations where more than one transfer techniques are available a first difference statistic is used to determine the type and level of the transfer noise for transfer methods

Further Examination of the Injection-Locked Dual Optoelectronic Oscillator

May 29, 2007
Author(s)
Kai Hudek, Archita Hati, W Zhou, David A. Howe, Craig W. Nelson
Optoelectronic oscillators (OEO), utilizing the low loss nature of optical links, can generate oscillations with very high Q values. The long delay line used in the oscillator can, however, support many modes of oscillation. Mode spacing is inversely

Improved Limits on Variation of the Fine Structure Constant and Violation of Local Position Invariance

May 29, 2007
Author(s)
Tara M. Fortier, Neil Ashby, James C. Bergquist, Marie Delaney, Scott A. Diddams, Thomas P. Heavner, Leo W. Hollberg, Wayne M. Itano, Steven R. Jefferts, K Kim, Windell Oskay, Thomas E. Parker, Jon H. Shirley, Jason Stalnaker, Filippo Levi, Luca Lorini
We report tests of Local Position Invariance (LPI) and constancy of fundamental constants from measurements of the frequency ratio of the 282-nm 199Hg + optical clock transition to the ground-state hyperfine splitting in 133Cs. Analysis of the frequency

Increased Cross-Correlation in Cascaded Four-Wave Mixing Processes

May 29, 2007
Author(s)
Jingyun Fan, Alan L. Migdall, L Wang
We report the measurement of increased noise cross-correlation between stokes and anti-stokes beams created in cascaded four-wave mixing processes with dual pump wavelengths, when two-photon light is efficiently created at the middle frequency. This method

Microwave Optoelectronic Oscillator with Optical Gain

May 29, 2007
Author(s)
Craig W. Nelson, Archita Hati, David A. Howe, W Zhou
Optoelectronic oscillators (OEO) are unique compared to radio-frequency (RF) oscillators in that they do not fundamentally require a RF gain element in order to satisfy the amplitude threshold condition for oscillation. All the energy required for

Microwave optoelectronic oscillator with optical gain

May 29, 2007
Author(s)
Craig Nelson, Archita Hati, David A. Howe, W Zhou
Optoelectronic oscillators (OEO) are unique compared to radio-frequency (RF) oscillators in that they do not fundamentally require a RF gain element in order to satisfy the amplitude threshold condition for oscillation. All the energy required for

Narrow band microwave radiation from a biased single-Cooper-pair transistor

May 29, 2007
Author(s)
Ofer Naaman, Joe Aumentado
We show that a single-Cooper-pair transistor (SCPT) electrometer emits narrow-band microwave radiation when biased in its sub-gap region. Photo-activation of quasiparticle tunneling in a nearby SCPT is used to spectroscopically detect this radiation, in a

Optical Fiber Vibration and Acceleration Model

May 29, 2007
Author(s)
Neil Ashby, David A. Howe, Jennifer A. Taylor, Archita Hati, Craig W. Nelson
We derive expressions for the group velocities of transverse electric and transverse magnetic electromagnetic waves in a stretched single-mode fiber. Stretching can occur either as a result of temperature changes of the spool on which the fiber is wound

Peak Deviation from Prediction in Atomic Clocks

May 29, 2007
Author(s)
Marc A. Weiss, A Masarie, Ron Beard
Results from a preliminary study of two GPS clocks tested on the ground show that the distribution of peak deviations from prediction cannot be assumed to be Gaussian. The standards are identical to models on board GPS block IIR satellites. The data were

Phase Noise of X-band Oscillator and Amplifier Technologies Compared

May 29, 2007
Author(s)
David A. Howe, Archita Hati
We compare best-in-class phase noise of different technologies of oscillators and amplifiers at X-band. Results are presented based on recent measurements at NIST. In particular, comparisons are made between mature technologies of multiplied quartz

Preliminary study on the vibration sensitivity performance of microwave components

May 29, 2007
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe, Neil Ashby, Jennifer A. Taylor, Kai Hudek, C. Hay, David Seidel, D. Eliyahu
Vibration sensitivity is an important specification for oscillators on mobile systems, Unmanned Aerial Vehicles (UAVs) etc. These systems must provide superior performance when subject to severe environmental conditions. Electronic oscillators often can

Stable Laser System for Probing the Clock Transition at 578 nm in Neutral Ytterbium

May 29, 2007
Author(s)
Christopher W. Oates, Zeb Barber, Jason Stalnaker, C Hoyt, Tara M. Fortier, Scott A. Diddams, Leo W. Hollberg
In this paper we describe a new laser system we have developed to probe the ultra-narrow 1S 0 -> 3P 0 clock transition at 578 nm in neutral ytterbium. The yellow light is produced by sum frequency generation in a periodically-poled waveguide. With

Fiber laser-based frequency combs with high relative frequency stability

May 28, 2007
Author(s)
Nathan R. Newbury, William C. Swann, Ian R. Coddington, J. C. Bergquist, Scott Diddams, Luca Lorini
We describe our current low-noise fiber-laser frequency comb and present measurements of its residual instability. Through a comparison with a Ti:Sapphire frequency comb, we measure residual fractional frequency instabilities (Allan deviation) of 6x10 -17

Testing Local Position Invariance with Four H Masers AND Four Cs Fountains

May 28, 2007
Author(s)
Neil Ashby, Thomas P. Heavner, Steven R. Jefferts, A Radnaev, Y Dudin
We report the most sensitive tests to date of the assumption of local position invariance (LPI) underlying general relativity, based on a seven year comparison of cesium and hydrogen atomic clocks (frequency standards). The latest results place an upper

Numerical Optimization of Matrix-Assisted Laser Desorption/Ionization Time-of- Flight Mass Spectrometry: Application to Synthetic Polymer Molecular Mass Distribution Measurement

May 26, 2007
Author(s)
William E. Wallace, Charles M. Guttman, Kathleen M. Flynn, Anthony J. Kearsley
A novel approach is described for the selection of optimal instrument parameters that yield a mass spectrum which best replicates the molecular mass distribution of a synthetic polymer. The application of implicit filtering algorithms is shown to be a
Displaying 32551 - 32575 of 73929
Was this page helpful?