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Search Publications by: Archita Hati (Fed)

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Displaying 51 - 75 of 90

Low Vibration Sensitivity Fiber Spools for Laser Stabilization

May 2, 2011
Author(s)
Archita Hati, T Li, B. Argence, A. Haboucha, H. Jiang, J. L. Dornaus, D Kone, A. Clairon, P. Lemonde, G. Santarelli, Craig W. Nelson, E. Burt
Mechanical vibration induced frequency noise is dominated at low Fourier frequencies in a fiber spool stabilized laser. Environmental vibration causes mechanical deformations in the fiber which induce phase fluctuations and then convert into excess

Characterization of Power-to-Phase Conversion in High-Speed P-I-N Photodiodes

February 1, 2011
Author(s)
Jennifer A. Taylor, Shubahshish Datta, Archita Hati, Craig W. Nelson, Franklyn J. Quinlan, Abhay Joshi, Scott A. Diddams
Fluctuations of the optical power incident on a photodiode can be converted into phase fluctuations of the resulting electronic signal due to nonlinear saturation in the semiconductor. This impacts overall timing stability (phase noise) of microwave

High Spectral purity oscillator at 40 GHz: Design using air-dielectric Cavity

June 2, 2010
Author(s)
Archita Hati, Craig W. Nelson, Billy F. Riddle, David A. Howe
We describe the design of a low-PM noise 40 GHz oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator to clean up the PM noise of a commercial 10 GHz dielectric resonator oscillator (DRO) multiplied by four. The

Phase Noise in the Photodetection of Ultrashort Optcial Pulses

June 2, 2010
Author(s)
Jennifer A. Taylor, Franklyn J. Quinlan, Archita Hati, Craig W. Nelson, Scott A. Diddams, Shubahshish Datta, Abhay Joshi
Femtosecond laser frequency combs provide an effective and efficient way to take an ultra-stable optical frequency reference and divide the signal down into the microwave region. In order to convert optical pulses into a usable rf signal, one must use high

Phase noise suppression in frequency comb generators

June 2, 2010
Author(s)
Craig W. Nelson, Archita Hati, J F. Nava-garcia, David A. Howe
We propose an idea to suppress the flicker (1/f) noise in radio frequency (RF) multiplier based frequency comb generators. Comb generators are often used for frequency multiplication in frequency synthesis. In general, comb generators apply high power to a

Phase-lock Loops in Vibration Environments

November 16, 2009
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
A popular scheme for achieving low phase noise across a large range of offset frequencies is to employ an oscillator at an output frequency with low far-from-carrier noise that is phase-locked to a reference that has low close-to-carrier noise. We

Vibration-induced PM and AM noise in microwave components

October 1, 2009
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
The performance of microwave components is sensitive to vibrations to some extent. Among them, microwave cables and connectors, bandpass filters, mechanical phase shifters and some non-linear components are the most sensitive. The local oscillator is one

Vibration-induced PM noise in oscillators and its suppression

January 1, 2009
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
High precision oscillators have significant applications in modern communication and navigation systems, radars, and sensors mounted in unmanned aerial vehicles, helicopters, missiles, and other dynamic platforms. These systems must provide their required

Vibration-induced PM Noise of A Rigid Optical Fiber Spool

December 1, 2008
Author(s)
Jennifer A. Taylor, Craig W. Nelson, Archita Hati, Neil Ashby, David A. Howe
Oscillators operating in field applications are subject to much more strenuous environmental effects than those in the laboratory. These environmental effects, like vibration and temperature fluctuation, have a great impact on the performance of the

Cancellation of Vibration-Induced Phase Noise in Optical Fibers

November 15, 2008
Author(s)
Archita Hati, Craig W. Nelson, Jennifer A. Taylor, David A. Howe
Vibration causes mechanical distortions in fiber-optic transmission lines that induce phase fluctuations. A scheme is described which enables electronic cancellation of vibration-induced phase noise in an optical fiber wound on a spool. We report 20 dB or

Relative Intensity Noise Suppression for Photonic Links

September 15, 2008
Author(s)
Craig Nelson, Archita Hati, David A. Howe
We propose and experimentally demonstrate a novel technique to reduce laser relative intensity noise (RIN). A RIN suppression servo is usually implemented by inserting an intensity modulator in the optical path and controlling measured light intensity with

Vibration-induced PM noise measurements of a rigid optical fiber spool

May 19, 2008
Author(s)
Jennifer A. Taylor, Craig W. Nelson, Archita Hati, Neil Ashby, David A. Howe
The opto-electronic oscillator (OEO) has emerged in recent years as an excellent low-noise source that rivals the best RF oscillators over broad offset frequencies. The main sources of noise in an OEO are the laser and RF modulator, photo detector, loop

Active Vibration-induced PM Noise Control in Optical Fibers: Preliminary Studies

May 29, 2007
Author(s)
David A. Howe, Archita Hati, Craig Nelson, Jennifer A. Taylor, Neil Ashby
Vibration causes mechanical distortions in fiber-optic transmission lines that induce time (phase) fluctuations. RF systems are increasingly using optical fibers in various ways and must occasionally operate in environments with acoustic and structure-born

Further Examination of the Injection-Locked Dual Optoelectronic Oscillator

May 29, 2007
Author(s)
Kai Hudek, Archita Hati, W Zhou, David A. Howe, Craig W. Nelson
Optoelectronic oscillators (OEO), utilizing the low loss nature of optical links, can generate oscillations with very high Q values. The long delay line used in the oscillator can, however, support many modes of oscillation. Mode spacing is inversely

Microwave Optoelectronic Oscillator with Optical Gain

May 29, 2007
Author(s)
Craig W. Nelson, Archita Hati, David A. Howe, W Zhou
Optoelectronic oscillators (OEO) are unique compared to radio-frequency (RF) oscillators in that they do not fundamentally require a RF gain element in order to satisfy the amplitude threshold condition for oscillation. All the energy required for

Microwave optoelectronic oscillator with optical gain

May 29, 2007
Author(s)
Craig Nelson, Archita Hati, David A. Howe, W Zhou
Optoelectronic oscillators (OEO) are unique compared to radio-frequency (RF) oscillators in that they do not fundamentally require a RF gain element in order to satisfy the amplitude threshold condition for oscillation. All the energy required for

Optical Fiber Vibration and Acceleration Model

May 29, 2007
Author(s)
Neil Ashby, David A. Howe, Jennifer A. Taylor, Archita Hati, Craig W. Nelson
We derive expressions for the group velocities of transverse electric and transverse magnetic electromagnetic waves in a stretched single-mode fiber. Stretching can occur either as a result of temperature changes of the spool on which the fiber is wound

Phase Noise of X-band Oscillator and Amplifier Technologies Compared

May 29, 2007
Author(s)
David A. Howe, Archita Hati
We compare best-in-class phase noise of different technologies of oscillators and amplifiers at X-band. Results are presented based on recent measurements at NIST. In particular, comparisons are made between mature technologies of multiplied quartz

Preliminary study on the vibration sensitivity performance of microwave components

May 29, 2007
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe, Neil Ashby, Jennifer A. Taylor, Kai Hudek, C. Hay, David Seidel, D. Eliyahu
Vibration sensitivity is an important specification for oscillators on mobile systems, Unmanned Aerial Vehicles (UAVs) etc. These systems must provide superior performance when subject to severe environmental conditions. Electronic oscillators often can

Merits of PM Noise Measurement over Noise Figure: A Study at Microwave Frequencies

October 1, 2006
Author(s)
Archita Hati, David A. Howe, Fred L. Walls, D. Walker
This paper addresses two issues: (i) it compares the usefulness of phase-modulation (PM) noise measurements vs. noise figure (NF) measurements in characterizing the merit of an amplifier, and (ii) it reconciles a general misunderstanding in using ¿174 dBc

Comparison of AM noise in commercial amplifiers and oscillators at X-band

June 5, 2006
Author(s)
Archita Hati, David A. Howe, Craig Nelson
In this paper we discuss the importance of amplitude modulated (AM) noise. AM noise is often neglected and considered as a minor problem. However, AM noise can become very important in high performance systems that require ultra-low phase modulated (PM)

Low Phase Noise Amplifier and Oscillator using Feed-Forward Technique at 10 GHz

June 5, 2006
Author(s)
Archita Hati, Craig Nelson, David A. Howe
We discuss the performance of a feed-forward amplifier (FFA) at 10 GHz. The feed-forward method is primarily used to suppress intermodulation distortion in amplifiers to suppress up-converted near-DC noise. The main amplifier in this configuration is a low