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Displaying 26 - 50 of 95

Optical system design for femtosecond-level synchronization of clocks

February 13, 2016
Laura C. Sinclair, William C. Swann, Jean-Daniel Deschenes, Hugo Bergeron, Fabrizio R. Giorgetta, Esther Baumann, Michael A. Cermak, Ian R. Coddington, Nathan R. Newbury
Synchronization of optical clocks via optical two-way time-frequency transfer across free-space links can result in time offsets between the two clocks below tens of femtoseconds over many hours. The complex optical system necessary to support such

Femtosecond synchronization of optical clocks over free-space links

December 11, 2015
Jean-Daniel Deschenes, Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Hugo Bergeron, Michael A. Cermak, Nathan R. Newbury
The use of optical clocks/oscillators in future ultra-precise navigation, gravitational sensing, and relativity experiments will require time comparison and synchronization over terrestrial or satellite free-space links. Here we demonstrate full

Towards a Reconfigurable Distributed Testbed to Enable Advanced Research and Development of Timing and Synchronization in Cyber-Physical Systems

December 9, 2015
Aviral Shrivastava, J C. Eidson, Marc A. Weiss, YaShian Li-Baboud, Hugo Andrade, Patricia Derler, Kevin Stanton
Timing and synchronization play a key role in advanced cyber-physical systems (CPS). Precise timing, as often required in safety-critical CPS, depends on hardware support for enforcement of periodic measure, compute, and actuate cycles. For general CPS

A compact optically coherent fiber frequency comb

August 18, 2015
Laura C. Sinclair, Jean-Daniel Deschenes, Lindsay I. Sonderhouse, William C. Swann, Isaac H. Khader, Esther Baumann, Nathan R. Newbury, Ian R. Coddington
We describe design and operation of a robust self-referenced, optically coherent frequency comb. The system robustness is derived from a combination of an optics package based on polarization-maintaining fiber, high signal-to-noise ratio (SNR) detection of

One-dimensional frequency-based spectroscopy

May 22, 2015
Joseph T. Hodges, A. Cygan, P. Wcislo, S. Wojtewicz, Piotr Maslowski, R. Ciurylo, D Lisak
Recent developments in optical metrology have tremendously improved the precision and accuracy of the horizontal (frequency) axis in measured spectra. However, the vertical (typically absorbance) axis is usually based on intensity measurements that are

Dielectric characterization by microwave cavity perturbation corrected for non-uniform fields

July 23, 2014
Nathan D. Orloff, Jan Obrzut, Christian J. Long, Thomas F. Lam, James C. Booth, David R. Novotny, James A. Liddle, Pavel Kabos
The non-uniform fields that occur due to the slot in the cavity through which the sample is inserted and those due to the sample geometry itself decrease the accuracy of dielectric characterization by cavity perturbation at microwave frequencies. To

Time-domain stabilization of carrier-envelope phase in femtosecond light pulses

May 7, 2014
Young-Jin Kim, Ian R. Coddington, William C. Swann, Nathan R. Newbury, Joohyung Lee, Seungchul Kim, Seung-Woo Kim
We report a time-domain method of stabilizing the carrier-envelope phase (CEP) of femtosecond pulses. Temporal variations of the pulse envelope and the carrier electric-field phase were separately detected with the aid of intensity cross-correlation and

Operation of an optically coherent frequency comb outside the metrology lab

March 13, 2014
Laura C. Sinclair, Ian R. Coddington, William C. Swann, Archita Hati, Kana Iwakuni, Nathan R. Newbury
Frequency combs can support cutting-edge measurements in areas that include optical clocks and oscillators, high-accuracy frequency and time transfer, precision spectroscopy from the UV to THz regimes, high-accuracy LIDAR, precise microwave photonics, and

Time Measurement

February 3, 2014
Michael A. Lombardi
An overview of time metrology, with emphasis on time interval measurements, and time synchronization. It covers the evolution of clocks and timekeeping, time scales, the fundamentals of time measurement, and the various time transfer technique used to

High-performance free-space photonic links for frequency/time transfer

September 8, 2013
Nathan R. Newbury, Fabrizio R. Giorgetta, William C. Swann, Laura C. Sinclair, Esther Baumann, Ian R. Coddington
We discuss optical two-way time and frequency transfer over air to connect remote optical clocks/oscillators. This method can link remote sites with a residual timing noise of femtoseconds and a residual fractional accuracy below 10^-18.

The impact of turbulence on high accuracy time-frequency transfer across free space

June 26, 2013
Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
Atmospheric optical path-length variations are measured across a 2-km optical link through a frequency comb-based system with femtosecond-level precision. Without mitigation, the turbulent piston effect will severely restrict time-frequency transfer from

Free-space optical time-frequency transfer over 2 km

June 9, 2013
William C. Swann, Fabrizio R. Giorgetta, Laura C. Sinclair, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
Precision free-space time-frequency transfer could advance fields where present microwave-based transfer is inadequate. We demonstrate an optical free-space link with femtosecond timing deviation and residual instability below 10−18 at 1000 seconds.

Optical two-way time and frequency transfer over free space

April 28, 2013
Fabrizio R. Giorgetta, William C. Swann, Laura C. Sinclair, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
The transfer of high-quality time-frequency signals between remote locations underpins many applications, including precision navigation and timing, clock-based geodesy, long-baseline interferometry, coherent radar arrays, tests of general relativity and

Towards Timely Intelligence in the Power Grid

February 25, 2013
YaShian Li-Baboud, Julien M. Amelot, Dhananjay Anand, Gerard N. Stenbakken, Thomas L. Nelson, James Moyne
One of the key lessons learned from the 2003 Northeast Blackout in the United States was the need for improved timing. The problem began as an isolated issue, but cascaded through the Northeastern grid. Timely situational awareness would likely have

In Search of a New Primary GPS Receiver for NIST

November 26, 2012
Marc A. Weiss
A previous publication showed problems with the current NIST Time and Frequency Division primary GPS receiver [1] when used for Precise Point Positioning (PPP)-based carrier phase time transfer. We confirm that, for this receiver, boundary discontinuities

A method for comparing remote optical clocks over a free-space optical link

July 9, 2012
William C. Swann, Fabrizio R. Giorgetta, Ian R. Coddington, Esther Baumann, Jean-Daniel Deschenes, Laura C. Sinclair, Alexander M. Zolot, Nathan R. Newbury
We demonstrate a method to compare optical clocks approaching 10-17 uncertainties through the exchange of optical pulses from phase-locked frequency combs. We discuss results over a 120 m air path and prospects for longer distances.

A thickness-shear MEMS resonator employing electromechanical transduction through a coplanar waveguide

May 21, 2012
Ward L. Johnson, Thomas M. Wallis, Pavel Kabos, Eduard Rocas, Juan C. Collado Gomez, Li-Anne Liew, Albert Davydov, Alivia Plankis, Paul R. Heyliger
The design, modeling, fabrication, and characterization of a vibrationally trapped thickness-shear MEMS resonator is presented. This device is intended to avoid various limitations of flexural MEMS resonators, including nonlinearity, clamping losses

Frequency characterization of a swept and fixed-wavelength external-cavity quantum cascade laser by use of a frequency comb

May 21, 2012
Kevin O. Knabe, Paul A. Williams, Fabrizio R. Giorgetta, Chris Armacost, Michael Radunsky, Nathan R. Newbury
The instantaneous optical frequency of an external-cavity quantum cascade laser (QCL) is characterized by comparison to a near-infrared frequency comb. Fluctuations in the instantaneous optical frequency are analyzed to determine the frequency noise power

Two-Way Link for Time Interval Comparison of Optical Clocks over Free-Space

May 11, 2012
Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Esther Baumann, Jean-Daniel Deschenes, Laura C. Sinclair, Alexander M. Zolot, Nathan R. Newbury
We demonstrate a free-space link for clock comparisons based on the two-way exchange of pulse trains from combs. The residual uncertainty is 5 * 10^17 in 100 seconds over a 120 m air path, with longer distances possible.

Generation of Ultrastable microwaves via optical frequency division

June 26, 2011
Tara M. Fortier, Matthew S. Kirchner, Jennifer A. Taylor, James C. Bergquist, Yanyi Jiang, Andrew D. Ludlow, Christopher W. Oates, Till P. Rosenband, Scott A. Diddams, Franklyn J. Quinlan, Nathan D. Lemke
A frequency-stabilized femtosecond laser optical frequency comb serves as a source of microwave signals having very low close-to-carrier phase noise. Comparison of two independent systems shows combined absolute phase noise of -100 dBc/Hz at an offset of 1

Searching for applications with a fine-toothed comb

April 1, 2011
Nathan R. Newbury
Frequency combs, like many ground-breaking technologies, are simple in concept; they results from the spectrum of any regular train of optical pulses. What is remarkable is that this simple picture can be actually realized in a number of different

The SIM Time Network

March 1, 2011
Michael A. Lombardi, Andrew N. Novick, J. Mauricio Lopez-Romero, Francisco Jimenez, Eduardo de Carlos Lopez, Jean-Simon Boulanger, Raymond Pelletier, Ricardo de Carvalho, Raul Solis, Harold Sanchez, Carlos A. Quevedo, Gregory Pascoe, Daniel Perez, Eduardo Bances, Leonardo Trigo, Victor Masil, Henry Postigo, Anthony Questelles
The Sistema Interamericano de Metrologia (SIM) is a regional metrology organization (RMO) whose members are the national metrology institutes (NMIs) located in the 34 nations of the Organization of American States (OAS). The SIM/OAS region extends

NIST Time and Frequency Bulletin

January 5, 2011
Petrina C. Potts
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services.
Displaying 26 - 50 of 95