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We study transmission and reflection properties of a perfectly amplifying as well as absorbing medium analytically by using the tight binding equation. Different expressions for transmittance and reflectance are obtained for even and odd…

Condensed Matter · Physics 2009-10-31 P. K. Datta

The probability distribution of the reflection coefficient for light reflected from a one-dimensional random amplifying medium with {\it cross-correlated} spatial disorder in the real and the imaginary parts of the refractive index is…

Disordered Systems and Neural Networks · Physics 2009-10-31 S. Anantha Ramakrishna , E. Krishna Das , G. V. Vijayagovindan , N. Kumar

Aberrations limit optical systems in many situations, for example when imaging in biological tissue. Machine learning offers novel ways to improve imaging under such conditions by learning inverse models of aberrations. Learning requires…

Optics · Physics 2021-04-30 Ivan Vishniakou , Johannes D. Seelig

The captured images under low light conditions often suffer insufficient brightness and notorious noise. Hence, low-light image enhancement is a key challenging task in computer vision. A variety of methods have been proposed for this task,…

Image and Video Processing · Electrical Eng. & Systems 2020-05-22 Cheng Zhang , Qingsen Yan , Yu zhu , Xianjun Li , Jinqiu Sun , Yanning Zhang

This paper is concerned with specular reflection removal based on tensor low-rank decomposition framework with the help of polarization information. Our method is motivated by the observation that the specular highlight of an image is…

Computer Vision and Pattern Recognition · Computer Science 2022-07-11 Moein Shakeri , Hong Zhang

We have made a high resolution study of the specularity of the atomic reflection from an evanescent wave mirror using velocity selective Raman transitions. We have observed a double structure in the velocity distribution after reflection: a…

A thin conducting sheet - graphene, for example - transmits, absorbs, and reflects radiation. A sheet that is very thin, even vanishingly so, can still produce 50% absorption at normal incidence if it has conductivity corresponding to half…

Mesoscale and Nanoscale Physics · Physics 2017-03-13 Matthew Mecklenburg , B. C. Regan

We have fabricated a layered nano-composite by alternating metal and gain medium layers, the gain dielectric consisting of a polymer incorporating optically pumped dye molecules. Exploiting an improved version of the effective medium…

Optics · Physics 2015-05-28 Carlo Rizza , Andrea Di Falco , Alessandro Ciattoni

Existing unpaired low-light image enhancement approaches prefer to employ the two-way GAN framework, in which two CNN generators are deployed for enhancement and degradation separately. However, such data-driven models ignore the inherent…

Computer Vision and Pattern Recognition · Computer Science 2021-12-28 Jize Zhang , Haolin Wang , Xiaohe Wu , Wangmeng Zuo

This paper proposes a self-supervised low light image enhancement method based on deep learning. Inspired by information entropy theory and Retinex model, we proposed a maximum entropy based Retinex model. With this model, a very simple…

Computer Vision and Pattern Recognition · Computer Science 2020-02-27 Yu Zhang , Xiaoguang Di , Bin Zhang , Chunhui Wang

Exact calculations of transmission and reflection coefficients in surface randomly corrugated optical waveguides are presented. As the length of the corrugated part of the waveguide increases, there is a strong preference to forward…

Disordered Systems and Neural Networks · Physics 2009-10-31 A. Garcia-Martin , J. A. Torres , J. J. Saenz , M. Nieto-Vesperinas

As light propagates along a waveguide, a fraction of the field can be reflected by Rayleigh scatterers. In high-quality-factor whispering-gallery-mode microresonators, this intrinsic backscattering is primarily caused by either surface or…

We consider evolution of multichannel excitations in longitudinally modulated waveguide arrays where refractive index either oscillates out-of-phase in all neighboring waveguides or when it is modulated in phase in several central…

On-chip photonic networks have the potential to transmit and route information more efficiently than electronic circuits. Recently, a number of silicon-based optical devices including modulators, buffers, and wavelength converts have been…

Optics · Physics 2015-05-19 Jacob T. Robinson , Michal Lipson

Although it is well recognized that waves propagating in periodic media have forbidden gaps in the continuous spectrum, it is still yet unknown about the minimum number and depth of periodic modulations for clear spectral formation. This…

Plasma Physics · Physics 2018-11-30 Lei Chang

A common bane of artificial reverberation algorithms is spectral coloration in the synthesized sound, typically manifesting as metallic ringing, leading to a degradation in the perceived sound quality. In delay network methods, coloration…

Audio and Speech Processing · Electrical Eng. & Systems 2025-12-19 Gloria Dal Santo , Karolina Prawda , Sebastian J. Schlecht , Vesa Välimäki

Contrast enhancement and noise removal are coupled problems for low-light image enhancement. The existing Retinex based methods do not take the coupling relation into consideration, resulting in under or over-smoothing of the enhanced…

Image and Video Processing · Electrical Eng. & Systems 2019-11-27 Yang Wang , Yang Cao , Zheng-Jun Zha , Jing Zhang , Zhiwei Xiong , Wei Zhang , Feng Wu

Visible light communication (VLC) has the potential to supplement the growing demand for wireless connectivity. In order to realise the full potential of VLC, channel models are required Discrete channel models based on semi-hidden Markov…

Signal Processing · Electrical Eng. & Systems 2019-02-20 Daniel G. Holmes , Ling Cheng , Mulundumina Shimaponda-Nawa , Ayokunle D. Familua , Adnan M. Abu-Mahfouz

In this paper, we consider an intelligent reflecting surface (IRS)-aided single-user system where an IRS with discrete phase shifts is deployed to assist the uplink communication. A practical transmission protocol is proposed to execute…

Information Theory · Computer Science 2019-12-24 Changsheng You , Beixiong Zheng , Rui Zhang

The light amplification by finite active media is used extensively in modern optics applications. In this paper the light amplification and scattering by cluster of small particles is studied analytically and numerically with the help of…

Optics · Physics 2014-12-16 V. V. Prosentsov