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 by:

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 126 - 150 of 216

Low noise synthesis of microwave signals from an optical source

May 26, 2005
Author(s)
John J. McFerran, Eugene N. Ivanov, A Bartels, G Wilpers, Christopher W. Oates, Scott A. Diddams, Leo W. Hollberg
We demonstrate the low noise synthesis of a harmonic comb of microwave frequencies using a femtosecond laser based synthesiser that is referenced to a cabity-stabilised laser. The residual phase noise is ~ -110dBc/Hz at 1 Hz from the 10 GHz harmonic. An

Ultra-high Stability Optical Frequency Standard Based on Laser-Cooled Neutral Calcium

May 22, 2005
Author(s)
G Wilpers, Christopher W. Oates, Scott A. Diddams, A Bartels, Windell Oskay, James C. Bergquist, Leo W. Hollberg
A beatnote between the Ca and Hg+ optical frequency standards via a mode-locked fs-laser frequency comb demonstrates the highest frequency stability measured to date. The high stability accelerates evaluation of the Ca standard's systematic shifts.

Optical frequency / wavelentgh references

April 25, 2005
Author(s)
Leo W. Hollberg, Christopher W. Oates, G Wilpers, C Hoyt, Zeb Barber, Scott A. Diddams, W Oskay, James C. Bergquist
Ideas for using visible light from atomic transitions for precision instrumentation and metrology go back at least to the 1800's. There are several good reasons to use optical frequencies, and with the scientific and technological advances of the last

International Comparisons of Femtosecond Laser Frequency Combs

April 1, 2005
Author(s)
Long-Sheng Ma, Zhiyi Bi, A Bartels, Lennart Robertsson, Massimo Zucco, Robert Windeler, G Wilpers, Christopher W. Oates, Leo W. Hollberg, Scott A. Diddams
Two types of international comparisons of femtosecond laser frequency combs have been performed in France and the USA. Five combs were involved in the comparisons. Three combs, of which two are transportable, employ nonlinear photonic crystal fiber (PCF)

Stabilized frequency comb with a self-referenced femtosecond Cr:forsterite laser

April 1, 2005
Author(s)
Kyoungsik Kim, Brian R. Washburn, G Wilpers, Christopher W. Oates, Leo W. Hollberg, Nathan R. Newbury, Scott A. Diddams, Jeffrey W. Nicholson, M. F. Yan
A frequency comb is generated with a Cr:forsterite femtosecond laser, spectrally broadened through a highly nonlinear optical fiber to span from 1.0 υm to 2.2 υm, and stabilized using the f-to-2f self-referencing technique. The repetition rate and the

Standards of time and frequency at the outset of the 21st century

November 19, 2004
Author(s)
Scott Diddams, James C. Bergquist, Steven R. Jefferts, Christopher W. Oates
In this paper we review state-of-the-art atomic time and frequency standards and discuss some of their uses in science and technology. After fifty years of development, microwave atomic clocks based on cesium have achieved fractional uncertainties below 1

The optical calcium frequency standards of PTB and NIST

November 5, 2004
Author(s)
U Sterr, C Degenhardt, H Stoehr, Ch. Lisdat, H Schnatz, J Helmcke, F Riehle, G Wilpers, Christopher W. Oates, Leo W. Hollberg
We describe the current status of the optical calcium frequency standard with laser-cooled neutral atoms realized in two different laboratories for the purpose of developing a possible future optical atomic clock. Frequency measurements performed at PTB

The era of coherent optical frequency references

September 29, 2004
Author(s)
Leo W. Hollberg, Christopher W. Oates, Scott Diddams, G Wilpers, A Bartels, C Hoyt, Zeb Barber
The past four years have shown a dramatic improvement in the performance of optical frequency references and in the methods by which they are calibrated and utilized. These revolutionary changes result from better stabilized lasers that probe narrow