AMPLIFICATION AND PHASE CONJUGATION OF WEAK SIGNALS

1993 ◽  
Vol 02 (01) ◽  
pp. 85-115 ◽  
Author(s):  
O.V. KULAGIN ◽  
G.A. PASMANIK ◽  
A.A. SHILOV
Keyword(s):  
Theoretical Approach ◽  
Phase Conjugation ◽  
High Sensitivity ◽  
Optical Systems ◽  
Experimental Investigations ◽  
Weak Signals ◽  
Optical Signals ◽  
Basic Concepts

The results of the study on phase conjugation of weak optical signals with the energy of units of photons are considered. Basic concepts of a semi-classical theoretical approach to describe amplification and phase conjugation (PC) of such signals are presented. A review is given on the experimental investigations that allowed for reaching a limit (about 1 photon for a mode) sensitivity of optical systems with PC-mirrors for a large (~ 105) number of resolution elements. High-sensitivity PC-mirror optical systems are demonstrated for a variety of applications.

Amplification and phase conjugation of weak signals

1992 ◽  
Vol 35 (6) ◽  
pp. 506-519 ◽  
Author(s):  
O V Kulagin ◽  
G A Pasmanik ◽  
A A Shilov
Keyword(s):  
Phase Conjugation ◽  
Weak Signals

scholarly journals DEVELOPMENT OF A HIGH-SENSITIVITY TORSION BALANCE TO INVESTIGATE THE THERMAL CASIMIR FORCE

2012 ◽  
Vol 14 ◽  
pp. 337-346 ◽  
Author(s):  
TODD GRAVESON ◽  
CHARLES RACKSON ◽  
WOO-JOONG KIM
Keyword(s):  
Casimir Force ◽  
High Sensitivity ◽  
Torsion Balance ◽  
Surface Patch ◽  
Experimental Investigations ◽  
Electric Force ◽  
Force Measurements ◽  
Semiconducting Materials ◽  
Proper Understanding ◽  
Actual Contribution

We report development of a high-sensitivity torsion balance to measure the thermal Casimir force. Special emphasis is placed on experimental investigations of a possible surface electric force originating from surface patch potentials that have been recently noticed by several experimental groups. By gaining a proper understanding of the actual contribution of the surface electric force in real materials, we aim to undertake precision force measurements to resolve the Casimir force at finite temperature in real metals, as well as in other semiconducting materials, such as graphene.

Theoretical approach to reconstructive and morphotropic phase transitions

2005 ◽  
Vol 220 (8) ◽  
Author(s):  
Pierre Tolédano
Keyword(s):  
Phase Transitions ◽  
Vanadium Oxide ◽  
Theoretical Approach ◽  
Phenomenological Approach ◽  
Oxide System ◽  
Basic Concepts

AbstractThe basic concepts of the phenomenological approach to reconstructive transitions are illustrated by a working example, and their specific properties are outlined. A theoretical approach to morphotropic transformations, which are transitions between phases with different stoichiometries, is introduced through the description of the vanadium-oxide system.

scholarly journals Stimulated Brillouin Review: Invented 50 Years Ago and Applied Today

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Elsa Garmire
Keyword(s):  
Optical Fibers ◽  
Brillouin Scattering ◽  
Phase Conjugation ◽  
Low Noise ◽  
Microwave Signal ◽  
Optical Systems ◽  
Frequency Combs ◽  
Scientific Instrumentation ◽  
Stimulated Brillouin ◽  
Signal Processors

Stimulated Brillouin scattering (SBS) is embedded today in a variety of optical systems, such as advanced high-power lasers, sensors, microwave signal processors, scientific instrumentation, and optomechanical systems. Reduction in SBS power requirements involves use of optical fibers, integrated optics, micro-optic devices, and now nano-optics, often in high Q cavities. It has taken fifty years from its earliest invention by conceptual discovery until today for SBS to become a practical and useful technology in a variety of applications. Some of these applications are explained and it is shown how they are tied to particular attributes of SBS: phase conjugation, frequency shifts, low noise, narrow linewidth, frequency combs, optical and microwave signal processing, etc.

Fluorescence microscopy of molecular organization and dynamics in cultured cells

1992 ◽  
Vol 50 (1) ◽  
pp. 550-551
Author(s):  
Yu-li Wang
Keyword(s):  
Image Processing ◽  
Cultured Cells ◽  
Single Cells ◽  
High Sensitivity ◽  
Light Level ◽  
Molecular Organization ◽  
Live Cells ◽  
Weak Signals ◽  
Simple Processing ◽  
Sensitivity Specificity

Over the past ten years various technical advances have allowed the direct study of molecular activities in cultured cells under a fluorescence microscope. Fluorescent probes are well known for their high sensitivity, specificity and amenability to various spectroscopic analyses. When used in conjunction with low-light-level detectors and image processing computers, high resolution images of weak signals from single cells can be successfully acquired. In addition, the availability of digitized images has greatly facilitated the extraction of photometric and morphometric information.We use Zeiss inverted microscopes equipped with epi-illuminators and Dage-MTI ISIT video cameras or Photometrics cooled CCD cameras. Custom incubator systems built on the microscope stages allow the maintenance of live cells for up to several days. The signals are processed with image processing systems (Imaging Technologies) interfaced with graphics workstations (Silicon Graphics, Model 3130 or 4D/20) or personal computers (386/33). All images are acquired by frame averaging/signal integration, followed by subtraction of the dark noise, and storage as computer files. A variation of this simple processing strategy has allowed the detection of extremely weak signals that are essentially invisible on unprocessed ISIT images. Computer programs are then used to display sequences or images as motion pictures, to measure the linear dimension and angular orientation, and to integrate intensities over defined areas.

Weak GNSS Signal Acquisition for Indoor Environments

2018 ◽  
pp. 485-514
Author(s):  
Seung-Hyun Kong
Keyword(s):  
Signal Processing ◽  
State Of The Art ◽  
High Sensitivity ◽  
Urban Canyon ◽  
Signal Acquisition ◽  
Indoor Environments ◽  
Weak Signals ◽  
Fast Acquisition ◽  
Processing Techniques ◽  
Signal Processing Techniques

High sensitivity and fast acquisition are two important goals that must be considered in the development of signal processing techniques for a GNSS acquisition function to meet the demands for LBS in GNSS-challenged environments, such as indoor and urban canyon. This chapter introduces the fundamentals of GNSS acquisition functions, GNSS acquisition techniques for new GNSS signals, and GNSS acquisition techniques achieving high sensitivity and fast acquisition. Therefore, this chapter contains useful information for engineers who study the fundamentals and principles of GNSS acquisition and the state-of-the-art GNSS signal acquisition techniques for weak signals.

Some Features of Pulse-Periodic Energy Supply in Supersonic Flow

2010 ◽  
Vol 5 (2) ◽  
pp. 43-54
Author(s):  
Vladimir N. Zudov ◽  
Pavel K. Tretyakov ◽  
Andrey V. Tupikin
Keyword(s):  
Physical Model ◽  
Energy Supply ◽  
Aerodynamic Drag ◽  
Reverse Flow ◽  
High Sensitivity ◽  
Quantitative Agreement ◽  
Frequency Effect ◽  
Experimental Investigations ◽  
Supply Source ◽  
Thermal Wake

In the present work, the results of numerical and experimental investigations of supersonic flows with a localized energy supply are considered. The energy supply region (the heat source) was formed by the plasma created by a focused pulsed-periodic laser emission either by combustion in the separation zone upstream of the blunted body. The main attention is paid to the unsteady effects the role of which is determining at the integral flow structure formation. A physical model of energy source is formulated. The numerical and experimental data on the structure of the flow around the source and the characteristics of a thermal wake arising behind the source are compared. The energy pulses frequency and capacity are shown to determine the wake properties: the formation and development of subsonic regions, vortex structures, and reverse flow regions. It follows from an analysis of the aerodynamic drag variation at a flow with a thermal wake of the energy supply source around blunt bodies that the energy and pulse as well as its duration are the main parameters determining the efficiency of the frequency effect. A high sensitivity of the results to the physical model accepted in numerical investigation is shown. The pressure variation dynamics on a conical surface is presented versus the frequency of pulses. Comparison with experiment has shown a good quantitative agreement.

Evolutionary and Ideation Concepts for Cybersecurity Education

2022 ◽  
pp. 535-546
Author(s):  
David A Gould ◽  
Gregory Block ◽  
Simon Cleveland
Keyword(s):  
Knowledge Sharing ◽  
Evolutionary Algorithm ◽  
Theoretical Approach ◽  
Cyber Security ◽  
Biological Theory ◽  
Evolutionary Processes ◽  
Security Education ◽  
Basic Concepts

Evolution is a well-established biological theory, but some basic concepts can be abstracted and applied to non-biological domains such as the education domain for the purposes of knowledge sharing. There is a gap in the literature regarding how evolutionary processes can be applied to cyber security education. This article presents the general evolutionary algorithm and pairs it with an ideation technique (SCAMPER) to illustrate how certain evolutionary processes can be applied to cyber security education and learning. This paper does not attempt to close the gap, but rather offer a theoretical approach to address the gap.

NONRECIPROCAL OPTICAL SYSTEMS WITH PHASE-CONJUGATING MIRRORS — A NEW CLASS OF OPTICAL IMAGING SYSTEM

1994 ◽  
Vol 03 (01) ◽  
pp. 89-100 ◽  
Author(s):  
A.A. LESHCHEV ◽  
V.G. SIDOROVICH ◽  
M.V. VASIL’EV ◽  
V.YU. VENEDIKTOV ◽  
G.A. PASMANIK
Keyword(s):  
Optical Imaging ◽  
Imaging System ◽  
Phase Conjugation ◽  
Numerical Results ◽  
Optical Systems ◽  
Lens System ◽  
New Class ◽  
Optical Imaging System

A method for removing some of the restrictions imposed in conventional phase conjugation imaging applications is proposed. It provides the possibility of transformation of both the image scale and its distance from the imaging lens system. Theoretical treatments and numerical results for the paraxial as well as the nonparaxial cases are presented, along with experimental demonstrations of the feasibility of this method.

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