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Search Publications by: Craig Nelson (Assoc)

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Displaying 1 - 25 of 107

Radio Frequency from Optical with Instabilities below 10^-15 - Generation and Measurement

August 8, 2025
Author(s)
Archita Hati, Marco Pomponio, Nicholas Nardelli, Tanner Grogan, Kyungtae Kim, Dahyeon Lee, Jun Ye, Tara Fortier, Andrew Ludlow, Craig Nelson
This paper presents a frequency synthesis that achieved exceptional stability by transferring optical signals to the RF domain at 100 MHz. These systems employ a cryogenic silicon cavity-stabilized laser at 1542 nm and an ultra-low expansion (ULE) glass

Deployment of a Transportable Yb Optical Lattice Clock

January 14, 2025
Author(s)
Tobias Bothwell, Tanner Grogan, Marco Pomponio, Takuma Nakamura, Craig Nelson, Archita Hati, Franklyn Quinlan, Andrew Ludlow, Wesley Brand, Robert Fasano, Yun-Jhih Chen, Thomas Akin, Joseph Whalen, Richard Fox, ignacio baldoni, Benjamin Rauf, michele giunta, ronald holzwarth, Steven Peil

Ultra-Low Phase Noise Frequency Division with Array of Direct Digital Synthesizers

December 25, 2023
Author(s)
Marco Pomponio, Archita Hati, Craig Nelson
In this article, we present a four-channel direct digital synthesis (DDS) design that operates with a common clock ranging from 500 MHz to 24 GHz and generates output frequencies up to 1.75 GHz. A key feature of this board is its custom field-programmable

30 GHz regenerative frequency divide-by-3

August 15, 2022
Author(s)
Archita Hati, Marco Pomponio, Connor Humiston, John Lettang, Craig Nelson
We report the performance of a 30 GHz to 10 GHz regenerative frequency divider. The proposed divider design incorporates the conventional Miller regenerative frequency divider (divide-by-2) with an additional regenerative path. We achieve output referred

10 GHz Generation with Ultra-Low Phase Noise via the Transfer Oscillator Technique

February 8, 2022
Author(s)
Nicholas Nardelli, Tara Fortier, Marco Pomponio, Esther Baumann, Craig Nelson, Thomas Schibli, Archita Hati
We generate 10 GHz microwave signals using the transfer oscillator technique, which employs digital and RF analog techniques to coherently remove the additive noise from an optical frequency comb. This method permits transfer of the frequency stability and

FPGA-based Low-Latency Digital Servo for Optical Physics Experiments

October 22, 2020
Author(s)
Marco Pomponio, Archita Hati, Craig Nelson
We propose a general-purpose dual-channel field-programmable gate array (FPGA) based digital servo with a minimum latency around 200 ns. This servo implements a proportional, dual- integration and derivative (PIID) controller along with internal numerical

Field Compressed Sensing

January 17, 2020
Author(s)
Anthony B. Kos, Fabio C. Da Silva, Jason B. Coder, Craig W. Nelson, Grace E. Antonucci, Archita Hati
Imaging solutions based on wave scattering seek real-time performance, high dynamic range, and spatial accuracy at scales spanning from nanometers to thousands of kilometers. Compressed sensing algorithms use sparsity to reduce sample size during image

Multipath Mitigation from FM-AM Correlation

October 3, 2019
Author(s)
Archita Hati, Craig W. Nelson
Multipath is one of the limiting factors for an accurate outdoor and indoor localization. We proposed an approach that uses a multipath mitigation derived from the undesired frequency-to- amplitude conversion of a frequency modulated (FM) signal

An atomic sensor for direct detection of weak microwave signals

August 16, 2019
Author(s)
Vladislav Gerginov, Fabio C. da Silva, Craig Nelson, Archita Hati
This paper demonstrates direct detection of weak signals at microwave frequencies based on parametric frequency conversion. The atomic medium is optically pumped by a resonant light field and prepared in a coherent atomic superposition by a weak microwave

W -Band Vibrometer for Noncontact Thermoacoustic Imaging

June 20, 2019
Author(s)
Archita Hati, Craig Nelson
Noncontact thermoacoustic imaging (TAI) has several desirable characteristics for applications such as explosive detection in high-water-content media. In this letter, we report a detection technique using millimeter-wave interferometry based on sensitive

W-band Vibrometer for Non-contact Thermoacoustic Imaging

June 20, 2019
Author(s)
Archita Hati, Craig W. Nelson
Non-contact thermoacoustic imaging (TAI) has several desirable characteristics for applications such as explosive detection in high-water content media. In this paper, we report a detection technique using mm-wave interferometry based on sensitive phase

Effect of Local Oscillator Performance on UWB Based Indoor Localization System

May 21, 2018
Author(s)
Archita Hati, Fabio C. Da Silva, Vladislav P. Gerginov, Craig W. Nelson
We discuss the performance of a commercial Ultra-wideband (UWB) ranging technique for indoor localization. We study the influence of local oscillator's phase noise and its frequency drifts due to temperature variations on the range estimation and ranging

Femtosecond timekeeping: slip-free optical clockwork for optical timescales

April 3, 2018
Author(s)
Daniel I. Herman, Stefan Droste, Esther Baumann, Jonathan Roslund, Dmitriy Churin, Arman Cingoz, Jean-Daniel Deschenes, Isaac H. Khader, William C. Swann, Craig W. Nelson, Nathan R. Newbury, Ian R. Coddington
The generation of true optical time standards will require the conversion of the highly stable optical frequency output of an optical atomic clock to a high-fidelity time output. We demonstrate comb-based clockwork that phase-coherently integrates ~7x10e20

Measurement of AM-to-PM Conversion in a Quartz-MEMS Resonator

May 9, 2016
Author(s)
Craig W. Nelson, Archita Hati, David A. Howe
This work investigates the new aspects of the non-linear response in a quartz-MEMS resonator at 635 MHz. We characterize its major cause of AM-to-PM conversion as a function of power and drive frequency; this is important in developing noise compensation

Power Splitter Thermal Noise Correlations in Cross-spectrum Noise Measurements

May 9, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We discuss collapse of the cross-spectrum phase noise measurement of thermally-limited oscillator due to anti-correlated thermal noise of the Wilkinson power splitter. We also examine effect of thermal noise of various resistive power splitters on such

Practical Evaluation of a 50 km Fiber Link Utilizing a Commercial Modem

May 9, 2016
Author(s)
Corey A. Barnes, Archita Hati, Craig W. Nelson, David A. Howe
We evaluate the stability of two-way time and frequency transfer over a 50 km fiber optic link established using a commercially available fiber optic modem. For this evaluation we report the residual phase noise, total Allan deviation, total time deviation

Tight real-time synchronization of a microwave clock to an optical clock across a turbulent air path

April 15, 2016
Author(s)
Hugo Bergeron, Laura C. Sinclair, William C. Swann, Craig Nelson, Jean-Daniel Deschenes, Esther Baumann, Fabrizio R. Giorgetta, Ian R. Coddington, Nathan R. Newbury
The ability to distribute the precise time and frequency from an optical clock to remote platforms could enable future precise navigation and sensing systems. Here we demonstrate tight, real-time synchronization of a remote microwave clock to a master

Cross-spectral Collapse from Anti-correlated Thermal Noise in Power Splitters

April 4, 2016
Author(s)
Craig Nelson, Archita Hati, David A. Howe
We discuss the cross-spectral collapse due to anti-correlated thermal noise that originates from the common-mode power divider (splitter) in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its

Oscillator PM-noise reduction from correlated AM-noise

March 11, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
We demonstrate a novel technique for reducing the phase modulation (PM) noise of an oscillator in steady state as well as under vibration. It utilizes correlation between PM noise and amplitude modulation (AM) noise that can originate from the oscillator's

Cross-spectrum Measurement of Thermal-noise Limited Oscillators

March 1, 2016
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
Cross-spectrum analysis is a commonly-used technique for the detection of phase and amplitude noise of a signal in the presence of interfering noise. It extracts the desired correlated noise from two time series which also contain uncorrelated interfering
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