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There is significant recent interest in designing new modulation schemes for doubly-selective channels with large delay and Doppler spreads, where legacy modulation schemes based on time-frequency signal representations underperform.…

Signal Processing · Electrical Eng. & Systems 2026-02-10 Nishant Mehrotra , Sandesh Rao Mattu , Robert Calderbank

Light propagation through multimode fibers suffers from spatial distortions that lead to a scrambled intensity profile. In previous work, the correction of such distortions using various wavefront control methods has been demonstrated in…

Repeatedly alternating the sign of dispersion along a waveguide substantially increases the bandwidth to input peak power efficiency of supercontinuum generation (SCG). Here, we explore, theoretically and numerically, how to optimize…

Optics · Physics 2020-07-16 Haider Zia

As the popularity of mobile photography continues to grow, considerable effort is being invested in the reconstruction of degraded images. Due to the spatial variation in optical aberrations, which cannot be avoided during the lens design…

Computer Vision and Pattern Recognition · Computer Science 2023-05-11 Shiqi Chen , Huajun Feng , Dexin Pan , Zhihai Xu , Qi Li , Yueting Chen

We demonstrate numerically a method of focusing two-photon field inside one-dimensional random media. The approach is based on coherent control of backscattering achieved by adaptive spectral pulse shaping. The spectral phases of a…

Optics · Physics 2016-03-02 Alex C. Han , Valery Milner

We present a detailed analysis of post-correlation beamforming (i.e. beamforming which involves only phased sums of the correlation of the voltages of different antennas in an array), and compare it with the traditionally used incoherent…

Instrumentation and Methods for Astrophysics · Physics 2018-09-19 Jayanta Roy , Jayaram N. Chengalur , Ue-Li Pen

This paper presents a pulse compansion, i.e. compression or expansion, technique based on co-propagating space-time modulation. An engineered asymmetric space-time modulated medium, co-propagating with a pulse compands the pulse…

Optics · Physics 2018-10-10 Nima Chamanara , Christophe Caloz

Purpose: This work proposes a novel RF pulse design for parallel transmit (pTx) systems to obtain uniform saturation of semisolid magnetization for Magnetization Transfer (MT) contrast in the presence of transmit field ($B_1^+$)…

We present time-resolved X-ray diffraction measurements using advanced timing schemes that provide high temporal resolution while also maintaining a high flux in the X-ray probe beam. The method employs patterned probe pulse sequences that…

This work explores a novel approach to mitigating turbulence in fusion plasmas through spatially modulated plasma profiles. By imposing a harmonic modulation on plasma parameters, we introduce conditions that alter the propagation…

Plasma Physics · Physics 2024-12-10 Ilya Shesterikov

The equations of motion in a macroscopically inhomogeneous porous medium saturated by a fluid are derived. As a first verification of the validity of these equations, a two-layer rigid frame porous system considered as one single porous…

Spatially exponential distributions of material properties are ubiquitous in many natural and engineered systems, from the vertical distribution of the atmosphere to acoustic horns and anti-reflective coatings. These media seamlessly…

Applied Physics · Physics 2024-04-09 Sichao Qu , Min Yang , Tenglong Wu , Yunfei Xu , Nicholas Fang , Shuyu Chen

This paper presents a numerical study on a fast marching method based back projection reconstruction algorithm for photoacoustic tomography in heterogeneous media. Transcranial imaging is used here as a case study. To correct for the phase…

Medical Physics · Physics 2015-01-21 Tianren Wang , Yun Jing

We present a general analysis for the interaction of a probe laser radiation with a coherently prepared molecular Raman medium. We describe a general formalism which includes dispersive effects, such as group velocity and group velocity…

Quantum Physics · Physics 2007-05-23 Fam Le Kien , K. Hakuta , A. V. Sokolov

Medical ultrasound imaging is the most widespread real-time non-invasive imaging system and its formulation comprises signal transmission, signal reception, and image formation. Ultrasound signal transmission modelling has been formalized…

Numerical Analysis · Mathematics 2023-08-09 Chiara Razzetta , Valentina Candiani , Marco Crocco , Federico Benvenuto

We study the time delay of reflected and transmitted waves in 1D disordered media with high transmission. Highly transparent and translucent random media are found in nature or can be synthetically produced. We perform numerical simulations…

Disordered Systems and Neural Networks · Physics 2022-11-30 Luis A. Razo-López , J. A. Méndez-Bermúdez , Victor A. Gopar

Acoustic wave modulation plays a pivotal role in various applications, including sound-field reconstruction, wireless communication, and particle manipulation, among others. However, current acoustic metamaterial and metasurface designs…

Audio and Speech Processing · Electrical Eng. & Systems 2024-03-19 Ao Chen , Xin Zhang

Thick biological tissues give rise to not only the scattering of incoming light waves, but also aberrations of the remaining unscattered waves. Due to the inability of existing optical imaging methodologies to overcome both of these…

Focusing waves inside inhomogeneous media is a fundamental problem for imaging. Spatial variations of wave velocity can strongly distort propagating wavefronts and degrade image quality. Adaptive focusing can compensate for such aberration,…

Image and Video Processing · Electrical Eng. & Systems 2020-06-15 William Lambert , Laura A. Cobus , Thomas Frappart , Mathias Fink , Alexandre Aubry

The propagation of a step pulse through a thick resonant absorber with homogeneously broadened absorption line is considered. It is shown that a specific subradiant state is naturally developed in the absorber due to the formation of the…

Quantum Physics · Physics 2015-06-18 R. N. Shakhmuratov
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