Background noise in optical communication systems
01 Oct 1970-Vol. 58, Iss: 10, pp 1571-1577
TL;DR: In this paper, the origin and magnitude of background noise that perturb optical communication receivers are discussed, including background radiation sources viewed directly, radiation reflected from background objects, and radiation scattered by the atmosphere into the receiver field of view.
Abstract: The origin and magnitude of the several kinds of background noise that perturb optical communication receivers are discussed, including background radiation sources viewed directly, radiation reflected from background objects, and radiation scattered by the atmosphere into the receiver field of view. An extensive bibliography on this topic is presented.
Citations
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TL;DR: This work reports on an architecture that acquires the two-dimensional spatial Fourier transform of the target object and determines its image signature, resolution, and signal-to-noise ratio in the presence of practical constraints such as atmospheric turbulence, background radiation, and photodetector noise.
Abstract: Computational ghost imaging is a structured-illumination active imager coupled with a single-pixel detector that has potential applications in remote sensing. Here we report on an architecture that acquires the two-dimensional spatial Fourier transform of the target object (which can be inverted to obtain a conventional image). We determine its image signature, resolution, and signal-to-noise ratio in the presence of practical constraints such as atmospheric turbulence, background radiation, and photodetector noise. We consider a bistatic imaging geometry and quantify the resolution impact of nonuniform Kolmogorov-spectrum turbulence along the propagation paths. We show that, in some cases, short-exposure intensity averaging can mitigate atmospheric-turbulence-induced resolution loss. Our analysis reveals some key performance differences between computational ghost imaging and conventional active imaging, and identifies scenarios in which theory predicts that the former will perform better than the latter.
167 citations
Cites background from "Background noise in optical communi..."
...The source of this background radiation in remote-sensing applications during the daytime is primarily diffusely scattered sunlight, which results in a background sky radiance for sensors looking up towards the sky, and a background upwelling radiance for sensors looking down at the Earth (terrestrial imaging systems may experience a combination of these two background sources) [25,26]....
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TL;DR: This study analyzes the performance of a short-distance terrestrial OWC system as a function of wavelength and performs a simulation of the system under different weather conditions, finding a modest improvement in link availability.
Abstract: Optical wireless communication (OWC) is gaining acceptance in an increasing number of sectors of science and industry, owing to its unique combination of features: extremely high bandwidth, rapid deployment time, license- and tariff-free bandwidth allocation, and low power consumption, weight, and size. However, the major drawback of OWC in terrestrial applications is the threat of downtime caused by adverse weather conditions, such as fog and haze. Several researchers have proposed and developed communication systems that use far-IR radiation to mitigate weather effects. In this study we analyze the performance of a short-distance terrestrial OWC system as a function of wavelength. A mathematical model for OWC link performance is derived. Using this model, we perform a simulation of our system under different weather conditions. From the results of our calculations, the improvement of link availability for 10 µm compared with 0.785–1.55 µm for a distance of 1-km propagation is 0.2% (99.6–99.8%). This modest improvement should be considered relative to the complexity and cost of quantum cascade laser transmitters and far-IR receivers.
154 citations
Cites background from "Background noise in optical communi..."
...Responsivity R is defined by qhc, ( 6 ) where q is the electron charge, h is Planck’s constant, c is the speed of light, and is the quantum efficiency of the detector....
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TL;DR: In this article, the quantum version of the Huygens-Fresnel diffraction integral is reviewed, along with the semiclassical and quantum theories of direct, homodyne, and heterodyne detection.
Abstract: Communication theory applied to lightwave channels is ordinarily carried out using the semiclassical theory of photodetection. Recent development of nonclassical light sources-whose photodetection statistics require the use of quantum theory-plus increasing interest in optics-based approaches to quantum information processing necessitates a thorough understanding of the similarities and distinctions between the semiclassical and quantum theories of optical communications. This paper is addressed to that need, focusing, for convenience, on the free-space communication channel using Gaussian states of light. The quantum version of the Huygens-Fresnel diffraction integral is reviewed, along with the semiclassical and quantum theories of direct, homodyne, and heterodyne detection. Maximally entangled Gaussian state light is used, in conjunction with quantum photodetection theory, to explain the nonclassical effects seen in Hong-Ou-Mandel interferometry and violation of the Clauser-Horne-Shimony-Holt form of Bell's inequality. The classical information capacities of several bosonic channels are reviewed, and shown to exceed what can be achieved using conventional optical receivers.
147 citations
Cites background from "Background noise in optical communi..."
...55μm then leads to N ∼ 10−6 ; nighttime Nλ values are several orders of magnitude lower [73]....
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...The environmental (background) noise entering this receiver in each spatiotemporal mode within the frequency band of interest is an independent, isotropic mixture of coherent states with average photon number [73]...
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TL;DR: An algorithm is described for estimating the level of this airlight given the assumption that it is constant throughout the image, based on finding the minimum of a global cost function and is applicable to both monochrome and color images.
Abstract: This paper is concerned with the mitigation of simple contrast loss due to added lightness in an image. This added lightness has been referred to as "airlight" in the literature since it is often caused by optical scattering due to fog or mist. A statistical model for scene content is formulated that gives a way of detecting the presence of airlight in an arbitrary image. An algorithm is described for estimating the level of this airlight given the assumption that it is constant throughout the image. This algorithm is based on finding the minimum of a global cost function and is applicable to both monochrome and color images. The method is robust and insensitive to scaling. Once an estimate of airlight is achieved, then image correction is straightforward. The performance of the algorithm is explored using the Monte Carlo simulation with synthetic images under different statistical assumptions. Several examples of before and after color images are given. Results with real video data obtained in poor visibility conditions indicate frame-to-frame consistency of better than 1% of maximum level
130 citations
Cites background from "Background noise in optical communi..."
...Optical scattering produces additional lightness present in some parts of the image, an effect that has been referred to as “atmospheric background radiation” [1], [2] or “airlight” [3], [4]....
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Proceedings Article•
15 Jun 2011TL;DR: In this paper, the effect of thermal, shot, background, and transmitter noises on the receiver performance is investigated. And the dominant noise components for the cases of using a PIN or an APD, and compare their performances at the presence or not of background radiations.
Abstract: P-i-N (PIN) diodes and avalanche photo-diodes (APD) are the most commonly used photo-detectors in terrestrial FSO systems. In this paper, we review the photo-detection process for the cases of PIN- and APD-based receivers and provide a comprehensive study of different noise sources that affect signal detection in an FSO system. We present a complete and precise model for the receiver noise by taking different receiver parts into account. In particular, we study the impact of thermal, shot, background, and transmitter noises on the receiver performance by considering practical and realistic case studies. We bring clearance on the impact of the interaction of signal and background noise due to non-linear characteristic of the photo-detector, and on the role of the trans-impedance load resistance. We discuss the dominant noise components for the cases of using a PIN or an APD, and compare their performances at the presence or not of background radiations.
117 citations
Cites background from "Background noise in optical communi..."
...Note that sometimes shot-noise and dark current are called external and internal quantum noises, respectively [24]....
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References
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TL;DR: In this article, the authors present concepts, terminology, and symbols for specifying and relating directional variations in reflectance and emissivity of an opaque surface element. But their relationship to more familiar concepts, including those of perfectly diffuse and specular reflectance, is not discussed.
Abstract: Concepts, terminology, and symbols are presented for specifying and relating directional variations in reflectance and emissivity of an opaque surface element. Their relationship to more familiar concepts, including those of perfectly diffuse and specular reflectance, is given, and they are applied to illustrative examples. It is shown that, when the usual reciprocity relationship holds, the reflectance for a ray incident on an opaque surface element is related by Kirchhoff's law to the emissivity of that element for a ray emitted along the same line in the opposite sense.
734 citations
TL;DR: In this paper, the refractive index of standard air has been tabulated for the range 0.2 to 20.0 μ, namely, 0.8(0.1)2.
Abstract: The refractive index of standard air has been tabulated for the range 0.2 to 20.0 μ, namely, 0.2(0.01)0.8; 0.8(0.1)2.0; 2.0(0.5)10.0; 10(1)20 μ. The values are based on Edlen’s formula. For computations of Rayleigh scattering, the scattering cross sections, the mass and volume scattering coefficients have been tabulated for the same values of wavelength as for the refractive index. The optical thickness and the transmissivity of the standard atmosphere is given next, and finally, the mean scattering coefficient for visual observations which is βv=1.23×10−7 (cm−1).
467 citations
TL;DR: In this article, the extinction coefficient, albedo of single scattering, and differential scattering and polarization properties of water clouds and hazes in the visible and infrared have been computed using the complete Mie series.
Abstract: The extinction coefficient, albedo of single scattering, and differential scattering and polarization properties of water clouds and hazes in the visible and infrared have been computed using the complete Mie series. The results with three types of size distributions are presented and compared with observations. These show a strong dependence of angular intensity and polarization patterns on the size distribution, the size range, and the dielectric and absorbing properties of water droplets at each wavelength. A peculiarity of scattering at angles near 45°, observed experimentally and independently by two authors, is corroborated by the numerical results. Prominent observational features characteristic of natural fog, such as an extremely bright and narrow aureole, cloudbows, and glories, are reproduced in a model cloud of spherical water droplets, with a wide distribution in droplet radius and a maximum concentration at a 4-μ radius.
317 citations
01 May 1965
TL;DR: In this paper, the theory of black body radiation, thermal noise, and quantum noise from a few basic physical principles was developed and applied to certain areas such as antenna theory and ideal receivers.
Abstract: One purpose of this article is to develop the theory of black body radiation, thermal noise, and quantum noise from a few basic physical principles. A second purpose is to show how these results apply to certain areas such as antenna theory and ideal receivers. It is hoped that having this related material collected and presented in the language of the electronics engineer will be of tutorial value.
194 citations