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Displaying 51 - 75 of 225

Precision limitations in coherent laser ranging due to speckle phase noise

August 15, 2014
Author(s)
Esther Baumann, Jean-Daniel Deschenes, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Nathan R. Newbury
The ultimate precision of coherent laser three-dimensional mapping of a diffusely scattering surface will be determined by speckle noise. Speckle phase noise gives rise both to apparent range outliers and to excess range noise during lateral scans

Speckle phase noise in coherent laser ranging: fundamental precision limitations

August 8, 2014
Author(s)
Esther Baumann, Jean-Daniel Deschenes, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Nathan R. Newbury
Frequency-modulated continuous-wave laser detection and ranging (FMCW LADAR) measures the range to a surface through coherent detection of the backscattered light from a frequency-swept laser source. The ultimate limit to the range precision of FMCW LADAR

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

May 7, 2014
Author(s)
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
Author(s)
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

High Resolution Frequency Comb Molecular Spectroscopy.

November 3, 2013
Author(s)
Ian R. Coddington, Alexander M. Zolot, Esther Baumann, Fabrizio R. Giorgetta, Greg B. Rieker, Jeffrey W. Nicholson, William C. Swann, Nathan R. Newbury
Frequency combs serve as an extremely high accuracy reference across broad portions of the optical spectrum. Dual frequency combs harness this accuracy and allow for fast and highly fidelity molecular spectroscopy.

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

September 8, 2013
Author(s)
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
Author(s)
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

A comb-calibrated FMCW LADAR for absolute distance measurements

June 15, 2013
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, Ian R. Coddington, Laura C. Sinclair, Kevin O. Knabe, William C. Swann, Nathan R. Newbury
We present a comb calibrated frequency-modulated continuous wave (FMCW) LADAR system for absolute distance measurements to diffuse or specular surfaces. The FMCW LADAR uses a MEMS-based external cavity laser that is swept quasi-sinusoidally over 1 THz at a

Free-space optical time-frequency transfer over 2 km

June 9, 2013
Author(s)
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.

Open-Path Dual-Comb Spectroscopy of Greenhouse Gases

June 9, 2013
Author(s)
Greg B. Rieker, Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Laura C. Sinclair, Christopher L. Cromer, Esther Baumann, Alexander M. Zolot, Nathan R. Newbury
Frequency-comb spectroscopy in the near-infrared is used to measure atmospheric CO2 and H2O concentrations over a 2-km outdoor open-air path. This technique shows promise for measurements over length scales between point sensors and satellite systems.

Precision metrology with coherent dual frequency combs

May 12, 2013
Author(s)
Nathan R. Newbury, Esther Baumann, Ian R. Coddington, Fabrizio R. Giorgetta, Greg B. Rieker, Laura C. Sinclair, William C. Swann, Alexander M. Zolot
Frequency combs have enabled a wide range of applications because of their unique combination of coherence and broad bandwidth. The comb provides 100,000's of comb teeth at precise, well-known optical frequencies that can support broadband accurate

Optical two-way time and frequency transfer over free space

April 28, 2013
Author(s)
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

Absolute spectroscopy of N2O near 4.5 um with a comb-calibrated, frequency-swept quantum cascade laser spectrometer

January 14, 2013
Author(s)
Kevin O. Knabe, Paul A. Williams, Fabrizio R. Giorgetta, Michael Radunsky, Chris Armacost, Sam Crivello, Nathan R. Newbury
We present absolute line center frequencies for 24 fundamental nu-3 ro-vibrational P-branch transitions near 4.5 um in N2O with an absolute frequency uncertainty of 800 kHz. The spectra were acquired with a swept laser spectrometer consisting of an

Broad-band frequency references in the near-infrared: accurate dual comb spectroscopy of methane and acetylene

December 1, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Ian R. Coddington, Nathan R. Newbury
The Doppler-limited spectra of methane between 176 THz and 184 THz (5870-6130 cm −1) and acetylene between 193 THz and 199 THz (6430-6630 cm −1) are acquired via comb-tooth resolved dual comb spectroscopy with frequency accuracy traceable to atomic

3D Precision Imaging with a Terahertz-bandwidth, Comb-calibrated Swept Laser

August 26, 2012
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, Ian R. Coddington, Kevin O. Knabe, Laura C. Sinclair, William C. Swann, Nathan R. Newbury
A frequency-comb and MEMS-based external-cavity laser are integrated into a THz-bandwidth LIDAR system. Range to a diffuse target is measured at sub-msec update times, a comb-based precision/accuracy of 100 nm, and a resolution of 150 microns. Example 3D

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

July 9, 2012
Author(s)
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.

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

May 21, 2012
Author(s)
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
Author(s)
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.

Comb-assisted swept laser spectroscopy with a mode-hop free tunable external cavity QCL

May 1, 2012
Author(s)
Kevin O. Knabe, Fabrizio R. Giorgetta, Nathan R. Newbury, Chris Armacost, Michael Radunsky, Sam Crivello, Timothy Day, Paul A. Williams
We demonstrate sub-MHz spectral resolution of N 2O absorption spectra acquired with a swept external-cavity quantum cascade laser (QCL) over 0.87 THz. The QCL frequency is monitored by sum -frequency generation with an optical fiber frequency comb.

Broad bandwidth trace gas and standoff detection with infrared frequency comb sources

March 11, 2012
Author(s)
Nathan R. Newbury, Alexander M. Zolot, Esther Baumann, Fabrizio R. Giorgetta, Florian B. Adler, Ian R. Coddington, Kevin O. Knabe, Lora L. Nugent-Glandorf, Paul A. Williams, Scott A. Diddams, Tyler W. Neely
An optical frequency comb based on the output of a mode-locked femtosecond laser can be used in spectroscopic studies and sensing applications. The broad array of frequency modes simultaneously provides high spectral resolution and broad wavelength

Direct-comb molecular spectroscopy with accurate, resolved comb teeth over 43 THz

February 15, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, Jeffrey W. Nicholson, William C. Swann, Ian R. Coddington, Nathan R. Newbury
We demonstrate a dual comb spectrometer using stabilized frequency combs spanning 176 THz to 219 THz (1370 nm to 1700 nm) in the near infrared. Measurements of amplitude and phase response at each individual comb tooth span the full 43 THz, generating ~430
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