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Displaying 76 - 100 of 235

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

High-resolution, high-accuracy dual comb spectroscopy with over 40 THz bandwidth

January 20, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Jeff Nicholson, Ian R. Coddington, Nathan R. Newbury
Most spectroscopic instruments directly measure optical wavelength, which is converted to frequency and calibrated against spectral features that have traditionally been measured using complicated frequency chain methods. In the past decade optical

Spectroscopy of the methane N3 Band with an accurate midinfrared coherent dual-comb spectrometer

December 28, 2011
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, William C. Swann, Alexander M. Zolot, Ian R. Coddington, Nathan R. Newbury
We demonstrate a high-accuracy dual-comb spectrometer centered at 3.4 υm. The amplitude and phase spectra of the P,, Q, and partial R branches of the methane Ņ3 band are measured at 25 to 100 MHz point spacing with resolution under 10 kHz and a signal-to

Dual comb-based characterization of rapidly tuned lasers

October 20, 2011
Author(s)
Fabrizio R. Giorgetta, Esther Baumann, Ian R. Coddington, William C. Swann, Nathan R. Newbury, Zeb W. Barber, Peter Roos
Time-resolved, high-accuracy and high-resolution spectroscopy of rapidly tuned cw lasers is critical to realizing their full potential for sensing, but is not possible with conventional spectrometers. We demonstrate a coherent dual-comb-based spectrometer

A coherent dual-comb spectrometer at 3.4 ym for accurate line center measurement of methane

October 10, 2011
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, Ian R. Coddington, William C. Swann, Alexander M. Zolot, Nathan R. Newbury
Doppler-broadened methane lines around 3.4 υm are measured with a coherent dual-comb spectrometer with an absolute-frequency axis. The obtained accuracy of the line-center frequency is 300 kHz, about 1 part per thousand of the linewidth.

Dual-comb-based characterization of rapidly tuned lasers

October 10, 2011
Author(s)
Fabrizio R. Giorgetta, Esther Baumann, Ian R. Coddington, William C. Swann, Nathan R. Newbury, Zeb W. Barber, Peter Roos
We demonstrate a technique to calibrate the instantaneous frequency versus time from a rapidly tuned cw laser. Our dual-comb-based spectrometer can measure optical waveforms tuned at 1500-THz/s rates over 5-THz bandwidths at high precision.

Dual comb-based characterization of rapidly tuned lasers

August 13, 2011
Author(s)
Fabrizio R. Giorgetta, Esther Baumann, Ian R. Coddington, William C. Swann, Nathan R. Newbury, Zeb Barber, Peter Roos
Time-resolved, high-accuracy and high-resolution spectroscopy of rapidly tuned cw lasers is critical to realizing their full potential for sensing, but is not possible with conventional spectrometers. We demonstrate a coherent dual-comb-based spectrometer

Precision spectroscopy with frequency combs at 3.4 ym

August 2, 2011
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, William C. Swann, Alexander M. Zolot, Ian R. Coddington, Nathan R. Newbury
We discuss precision spectroscopy with a comb-based spectrometer at 3.4 υm. Our goal is to explore comb-based spectroscopy as an alternative method for fast, highly resolved, accurate measurements of gas line shapes. The spectrometer uses dual 1.5 υm

Frequency-comb based approaches to precision ranging laser radar

June 20, 2011
Author(s)
Nathan R. Newbury, Tze-Ann Liu, Ian R. Coddington, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann
The output of pulsed femtosecond lasers can be controlled to generate pulse trains with very precise timing and optical frequency. This source can be used in different ways to support precision coherent LIDAR. We will discuss several implementations of

Dual comb spectroscopy from 1.25 to 1.7 ym

May 1, 2011
Author(s)
Alexander M. Zolot, Ian R. Coddington, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Nathan R. Newbury
A coherent dual comb spectrometer spanning much of the near infrared was constructed from broadened erbium fiber lasers. Gas phase water, methane and acetylene spectra were measured and characterized toward establishing new frequency standards.

Dual-comb based measurement of frequency agile lasers.

May 1, 2011
Author(s)
Ian R. Coddington, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Nathan R. Newbury
Properly stabilized, frequency combs form high accuracy references across much of the optical spectrum. Here we employ dual frequency combs to harness this accuracy for fast and high resolution measurements of swept CW sources.

Characterizing arbitrary CW waveforms with 1500 THz/s chirp rates

April 5, 2011
Author(s)
Ian R. Coddington, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Nathan R. Newbury
A Dual frequency comb interferometer was constructed to monitor cw laser chirp rates exceeding 1500 THz/s with MHz level resolution and accuracy over a 3 THz spectral sweep. Monitoring of the chirped laser is continuous. Additionally, absolute frequency

Searching for applications with a fine-toothed comb

April 1, 2011
Author(s)
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