المؤلفون: Korobko, Dmitry A¹ (AUTHOR) korobkotam@rambler.ru, Zolotovskii, Igor O^1,2 (AUTHOR), Moiseev, Sergey G^1,2,3 (AUTHOR), Kadochkin, Alexey S^1,2 (AUTHOR), Svetukhin, Vyacheslav V⁴ (AUTHOR)

المصدر: Journal of Optics. Jan2022, Vol. 24 Issue 1, p1-8. 8p.

مصطلحات موضوعية: *ELECTROMAGNETIC wave propagation, *SUBMILLIMETER waves, *POLARITONS, *SCHRODINGER equation, *SURFACE plasmons, *PULSE generators, *METALLIC films, *NONLINEAR waves

مستخلص: Propagation of high-intensity electromagnetic waves in a waveguide structure could initiate nonlinear effects resulting in drastic changes of their spatial and temporal characteristics. We study the modulation instability effect induced by propagation of surface plasmon polaritons in a silver thin-film waveguide. The nonlinear Schrodinger equation for propagating surface plasmon wave is obtained. It is shown numerically that the modulation instability effect can give rise to ultrafast spatial redistribution and longitudinal localization of surface plasmon-polariton wave energy in subwavelength scale. The dependence of plasmon wave dispersion and nonlinear characteristics on metal film thickness is considered. We demonstrate that the use of films with the thickness varying along the waveguide length allows reduction of the generated pulse width and increase of frequency comb bandwidth. The proposed technique is promising for design of ultra-compact (tens of nm) optical generators delivering pulse trains with the repetition rate higher than 1 THz. [ABSTRACT FROM AUTHOR]

المؤلفون: Laverde, Julián, Moreno, Jaime, Castańeda, Román

المصدر: Journal of Optics; Jul2021, Vol. 23 Issue 7, p1-8, 8p

مصطلحات موضوعية: ELECTROMAGNETIC fields, ELECTROMAGNETIC waves, COMPUTATIONAL electromagnetics, GAUSSIAN beams, WIGNER distribution, ALGORITHMS, ELECTROMAGNETIC wave propagation

مستخلص: The non-paraxial propagation of electromagnetic wave fields seems to be a condition of the micro and nano-optics. At these scales, spatial correlation is unavoidable and occurs in two important features, i.e. the spatial coherence and spatially correlated polarization. It makes the description of the electromagnetic wave fields challenging in both mathematical formalism and physical interpretation. In this context, the algorithmic implementation of the model plays a crucial role, not only for the theoretical description but also for the experimental development, mainly by taking into account that the theoretical model is able to predict the field's behavior and properties in experimental scenarios both accessible and still non-accessible by technology. In this paper, the basic theory of the spatially correlated electromagnetic wave fields is discussed. Its capabilities are illustrated by the predictions provided by a modular algorithm, which uses the experimental specifications as individual entries, in close resemblance to the experimental setup. [ABSTRACT FROM AUTHOR]

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المؤلفون: Tao Li, Yu-lin Wang, Cheng-ping Huang, Yong Zhang, Zhikai Li

المصدر: Journal of Optics. 50:495-501

مصطلحات موضوعية: Physics, Coupling, business.industry, Phase (waves), Michelson interferometer, Port (circuit theory), Interference (wave propagation), Unitary state, Atomic and Molecular Physics, and Optics, law.invention, Optics, law, business, Beam splitter, Group delay and phase delay

الوصف: In this paper, we theoretically propose and demonstrate a non-unitary beam-splitter (BS) by introducing coupling losses at the interface of the plasmonic waveguide and multimode dielectric waveguide (DW). The coupling losses enable us to modify the reflection and transmission factors, which can result in arbitrary shift of interference curves of two outputs. Specially, the lossy non-unitary BS can tune the amplitudes and phases of two outputs, even making them change synchronously, regardless of input phase differences. After a $$\pi /2$$ phase delay in one arm, these two outputs are fed into another multimode DW. This DW is a normal unitary BS, working like the Michelson interferometer, where anti-synchronous interference can take place. At last, the whole device outputs an invariant zero energy state in one port, exhibiting a phase-insensitive performance. Our study provides a versatile design platform to realize non-unitary/unitary BS and construct more multi-functional devices.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::6abc18caa8aea83eb32682de7b5a19adTest
https://doi.org/10.1007/s12596-021-00728-5Test

المؤلفون: Xiaoqian Tian, Shaoyi Li, Kai Yang, Xi Yang, Jun Ma

المصدر: Journal of Optics. 50:264-277

مصطلحات موضوعية: Matching (graph theory), business.industry, Computer science, Bayesian probability, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Stability (learning theory), Probabilistic logic, Bayesian network, Pattern recognition, 02 engineering and technology, Interference (wave propagation), Atomic and Molecular Physics, and Optics, Naive Bayes classifier, ComputingMethodologies_PATTERNRECOGNITION, 020210 optoelectronics & photonics, Optics, Missile, 0202 electrical engineering, electronic engineering, information engineering, Artificial intelligence, business

الوصف: The development of infrared decoy countermeasure technologies has resulted in the complexity of the air combat environment. Therefore, higher requirements are put forward considering the infrared imaging-guided air-to-air missile anti-interference target recognition technology. The release of infrared decoys destroys the completeness, saliency and stability of target features. It is difficult for statistical pattern recognition methods based on feature fusion and matching to cover all of the confrontation conditions. In the present study, a Bayesian probabilistic recognition model is proposed that deals with uncertain information about targets and decoys. The proposed model deals with the interference of the air battlefield with the confrontation environment. Moreover, it simulates some functions of the human visual cognition and improves the target recognition ability when interference exists. Furthermore, numerous simulation data samples are utilized to solve the network structure as well as parameters of the Bayesian recognition model and the probabilistic definitions of the target and interference are achieved. Finally, a new aerial infrared target recognition algorithm is constructed based on prior information and the probability recognition model. Results of simulation experiments indicate that the recognition rate of the anti-interference recognition algorithm based on the Bayesian network reaches 90.73%, which is 6.905% higher than that of the anti-interference recognition algorithm based on Naive Bayes classifier in the tested air combat anti-interference simulation image dataset. Moreover, it can solve the problem of anti-interference target recognition to a certain extent such as false targets and target occlusion.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::482eb58db623736ce03993fc345a167cTest
https://doi.org/10.1007/s12596-021-00701-2Test

المؤلفون: Haidan Mao, Yuanqian Liu, Linfei Chen, Yuan Zhong, Wenwen Gan

المصدر: Journal of Optics. 49:216-223

مصطلحات موضوعية: Diffraction, business.industry, Computer science, Fourier optics, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Phase (waves), Data_CODINGANDINFORMATIONTHEORY, 02 engineering and technology, Grating, Interference (wave propagation), Encryption, Atomic and Molecular Physics, and Optics, Superposition principle, 020210 optoelectronics & photonics, Optics, Computer Science::Multimedia, Ciphertext, 0202 electrical engineering, electronic engineering, information engineering, business, Algorithm, Computer Science::Cryptography and Security

الوصف: This paper presents an optical image encryption system based on grating diffraction imaging and interference superposition principle. When the encryption is performed, an image is encrypted into several ciphertexts by vector superposition, and a random phase is added to each ciphertext to prevent the generation of contours in decryption. During the decryption process, the nature of the grating diffraction in the 4f system would be used, and then, all the ciphertexts would be superimposed on the same position at the output plane, so that an accurate decrypted image can be obtained. Since the random phase is especially processed during encryption, only the complete information of the ciphertexts needs to be known at the time of decryption, and the random phase information is not needed to recover the image. If we do not have enough information of the ciphertexts, we cannot recover the correct decrypted image. Computer simulations prove its possibility.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::454935714c3a6c5e2271625e4fe9e0b6Test
https://doi.org/10.1007/s12596-020-00609-3Test

المؤلفون: Sucharita Bhattacharyya, Anup Kumar Thander

المصدر: Journal of Optics. 48:345-356

مصطلحات موضوعية: Physics, Wave propagation, business.industry, Computation, Mathematical analysis, Finite difference method, Physics::Optics, Classification of discontinuities, Waveguide (optics), Atomic and Molecular Physics, and Optics, Optics, Conjugate gradient method, Photonics, business, Refractive index

الوصف: Following the recent success with polarized E-field solutions, an efficient and highly accurate semi-vectorial H-field mode solver is proposed for various rib waveguides based on higher (fourth)-order compact FDM in combination with a conjugate gradient (CG) type of iteration. Here, optical waveguide modeling is designed by incorporating the modal index and modal birefringence concept into the refractive index profiles (RIPs) of two specific semiconductor (GaAs/GaAlAs and GeSi) rib waveguide structures for simulating the performances of various photonic integated circuits and corresponding field profiles of guided modes are shown through the surface and contour plots. It is to be confirmed that the used algorithm takes full account of vertical and horizontal discontinuities of RIPs in cell interfaces within the specific waveguide structure where the numerical results ensure its behavior for stability and convergence with less computational time. For Hx and Hy modes, computed modal index and normalised index values are found to be in perfect agreement with other published results. Most importantly, the variations of these indices with waveguide structure parameters help to identify their optimized values which play very decisive role so far as their fabrications are concerned. Also study of confinement factor computation and modal birefringence provides some important additional deep understanding with which the optimized index values clearly verify the material dependence for effective wave propagation.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::1c43341fe13ee4f7450d7c2588d07da4Test
https://doi.org/10.1007/s12596-019-00546-wTest

المؤلفون: Oscar Quevedo-Teruel^1,2,3 oscarqt@kth.se, Hongsheng Chen^2,4 hansomchen@zju.edu.cn, Ana Díaz-Rubio^2,5 ana.diazrubio@aalto.fi, Gurkan Gok⁶, Anthony Grbic⁷, Gabriele Minatti⁸, Enrica Martini⁸, Stefano Maci⁸, George V Eleftheriades⁹, Michael Chen⁹, Nikolay I Zheludev^10,11, Nikitas Papasimakis^10,11, Sajid Choudhury¹², Zhaxylyk A Kudyshev¹², Soham Saha¹², Harsha Reddy¹², Alexandra Boltasseva¹², Vladimir M Shalaev¹², Alexander V Kildishev¹², Daniel Sievenpiper¹³

المصدر: Journal of Optics. Jul2019, Vol. 21 Issue 7, p1-1. 1p.

مصطلحات موضوعية: *REMOTE sensing by radar, *ELECTROMAGNETIC wave propagation, *ELECTROMAGNETIC devices, *TRANSMITTERS (Communication), *WAVEGUIDES, *ELECTROMAGNETIC waves

مستخلص: Metasurfaces are thin two-dimensional metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions. For example, metasurfaces have been demonstrated to produce unusual scattering properties of incident plane waves or to guide and modulate surface waves to obtain desired radiation properties. These properties have been employed, for example, to create innovative wireless receivers and transmitters. In addition, metasurfaces have recently been proposed to confine electromagnetic waves, thereby avoiding undesired leakage of energy and increasing the overall efficiency of electromagnetic instruments and devices. The main advantages of metasurfaces with respect to the existing conventional technology include their low cost, low level of absorption in comparison with bulky metamaterials, and easy integration due to their thin profile. Due to these advantages, they are promising candidates for real-world solutions to overcome the challenges posed by the next generation of transmitters and receivers of future high-rate communication systems that require highly precise and efficient antennas, sensors, active components, filters, and integrated technologies. This Roadmap is aimed at binding together the experiences of prominent researchers in the field of metasurfaces, from which explanations for the physics behind the extraordinary properties of these structures shall be provided from viewpoints of diverse theoretical backgrounds. Other goals of this endeavour are to underline the advantages and limitations of metasurfaces, as well as to lay out guidelines for their use in present and future electromagnetic devices. This Roadmap is divided into five sections: 1. Metasurface based antennas. In the last few years, metasurfaces have shown possibilities for advanced manipulations of electromagnetic waves, opening new frontiers in the design of antennas. In this section, the authors explain how metasurfaces can be employed to tailor the radiation properties of antennas, their remarkable advantages in comparison with conventional antennas, and the future challenges to be solved. 2. Optical metasurfaces. Although many of the present demonstrators operate in the microwave regime, due either to the reduced cost of manufacturing and testing or to satisfy the interest of the communications or aerospace industries, part of the potential use of metasurfaces is found in the optical regime. In this section, the authors summarize the classical applications and explain new possibilities for optical metasurfaces, such as the generation of superoscillatory fields and energy harvesters. 3. Reconfigurable and active metasurfaces. Dynamic metasurfaces are promising new platforms for 5G communications, remote sensing and radar applications. By the insertion of active elements, metasurfaces can break the fundamental limitations of passive and static systems. In this section, we have contributions that describe the challenges and potential uses of active components in metasurfaces, including new studies on non-Foster, parity-time symmetric, and non-reciprocal metasurfaces. 4. Metasurfaces with higher symmetries. Recent studies have demonstrated that the properties of metasurfaces are influenced by the symmetries of their constituent elements. Therefore, by controlling the properties of these constitutive elements and their arrangement, one can control the way in which the waves interact with the metasurface. In this section, the authors analyze the possibilities of combining more than one layer of metasurface, creating a higher symmetry, increasing the operational bandwidth of flat lenses, or producing cost-effective electromagnetic bandgaps. 5. Numerical and analytical modelling of metasurfaces. In most occasions, metasurfaces are electrically large objects, which cannot be simulated with conventional software. Modelling tools that allow the engineering of the metasurface properties to get the desired response are essential in the design of practical electromagnetic devices. This section includes the recent advances and future challenges in three groups of techniques that are broadly used to analyze and synthesize metasurfaces: circuit models, analytical solutions and computational methods. [ABSTRACT FROM AUTHOR]

المؤلفون: Slava G Turyshev^1,2 turyshev@jpl.nasa.gov, Viktor T Toth³

المصدر: Journal of Optics. Apr2019, Vol. 21 Issue 4, p1-1. 1p.

مصطلحات موضوعية: *OPTICAL diffraction, *ELECTROMAGNETIC wave propagation, *SOLAR wind, *SOLAR system, *LIGHT, *MIE scattering

مستخلص: We study the propagation of electromagnetic (EM) waves in the solar system and develop a Mie theory that accounts for the refractive properties of the free electron plasma in the extended solar corona. We use a generic model for the electron number density distribution and apply the eikonal approximation to find a solution in terms of Debye potentials, which is then used to determine the EM field both within the inner solar system and at large heliocentric distances. As expected, the solution for the EM wave propagating through the solar system is characterized by a plasma-induced phase shift and related change in the light ray’s direction of propagation. Our approach quantitatively accounts for these effects, providing a wave-optical treatment for diffraction in the solar plasma. As such, it may be used in practical applications involving big apertures, large interferometric baselines or otherwise widely distributed high-precision astronomical instruments. [ABSTRACT FROM AUTHOR]

المؤلفون: Reinaldo Welti

المصدر: Journal of Optics. 23:125603

مصطلحات موضوعية: Physics, Superposition principle, Optics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Physics::Optics, Interference (wave propagation), business, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials

الوصف: In the explanations of the double slit experiment it is usually assumed that the superposition of the diffracted waves by two separate slits (one open and another closed) is the same as superimposing the diffracted waves when both slits are open at the same time. This naïve use of the superposition principle is generally not valid in either classical electromagnetism or quantum mechanics. As we will see, the diffraction diagram of one of the slits is altered when the other is open and when the slits are closer, the interaction between them is greater. In this work we will analyse the interaction between different types of sources (antennas, loudspeakers and, of course, slits) and we will show how this interaction explains the apparent anomalies in energy conservation and also the recent results of Young’s interference that show that the total diffracted intensity is reduced or increased depending on the distance between the slits. We also make a brief comment on the contributions of our work to the supposed looped trajectories of energy in interference phenomena.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::37b7a237b343d18837f3871a0a901940Test
https://doi.org/10.1088/2040-8986/ac2fd1Test

المؤلفون: Xinyuan Yuwen, Ren Ren, Yilin Wang

المصدر: Journal of Optics. 23:115607

مصطلحات موضوعية: Physics, symbols.namesake, Optics, business.industry, Gaussian, symbols, Laguerre polynomials, Interference (wave propagation), business, Optical vortex, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Intensity (physics)

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::339f85ebb8c2b37138e6896de9ed0448Test
https://doi.org/10.1088/2040-8986/ac2bf7Test