A5004105482- Photonic and Optical Devices
- Metamaterials and Metasurfaces Applications
- Optical Coatings and Gratings
- Semiconductor Lasers and Optical Devices
- Photonic Crystals and Applications
- Advanced Antenna and Metasurface Technologies
- Electromagnetic Scattering and Analysis
- Liquid Crystal Research Advancements
- Optical Polarization and Ellipsometry
- Advanced Fiber Laser Technologies
- Advanced Fiber Optic Sensors
- Relativity and Gravitational Theory
- Optical Network Technologies
- Orbital Angular Momentum in Optics
- Optical and Acousto-Optic Technologies
- Experimental and Theoretical Physics Studies
- Quantum and Classical Electrodynamics
- Photorefractive and Nonlinear Optics
- Mechanical and Optical Resonators
- Semiconductor Quantum Structures and Devices
- Geophysics and Sensor Technology
- Nonlinear Dynamics and Pattern Formation
- Quantum optics and atomic interactions
- Laser-Matter Interactions and Applications
- Electromagnetic Simulation and Numerical Methods
Imperial College London
2015-2024
Philadelphia Fire Department
2023
Lancaster University
2019
Cockcroft Institute
2019
Sci-Tech Daresbury
2019
Chinese University of Hong Kong
2002
University of Bath
1988-1995
Center for Creative Leadership
1976
We introduce a new type of electromagnetic cloak, the spacetime cloak (STC), which conceals events rather than objects. Non-emitting occurring during restricted period are never suspected by distant observer. The works locally manipulating speed light an initially uniform distribution, whilst rays themselves always follow straight paths. Any 'perfect' would necessarily rely upon technology metamaterials, has already been shown to be capable deforming in ways hitherto unforeseen—to produce,...
We study electromagnetic wave propagation in media which the effective relative permittivity and permeability are allowed to take any value upper half of complex plane. A general condition is derived for phase velocity be oppositely directed power flow. That extends recently studied case both simultaneously negative, include dissipation as well. An illustrative demonstrates that spectrum divides into five distinct regions.
Transformation Optics asks Maxwell's equations what kind of electromagnetic medium recreate some smooth deformation space.The guiding principle is Einstein's covariance: that any physical theory must take the same form in coordinate system.This requirement fixes very precisely required medium.
Using the principle of causality as expressed in Kramers-Kronig relations, we derive a generalized criterion for negative refractive index that admits imperfect transparency at an observation frequency omega. It also allows us to relate global properties loss (i.e., its response) local behavior However, causality-based criteria rely on group velocity, not Poynting vector. Since two are equivalent, provide some simple examples compare criteria.
Recently, scalar coupled-wave theory has been employed to analyze a medium with periodic time-varying permittivity, providing simple expressions and, consequently, straightforward insights into the parametric amplification mechanism. Here, we combine such an approach Möbius transformation method investigate dispersion and optical response of finite "time-slab" aforementioned medium. We demonstrate temporal analog Bragg grating, discuss differences its spatial counterpart, examine nontrivial...
We demonstrate that gravitational waves, upon interacting with co-propagating electromagnetic radiation, induce distinctive sidebands on the modulated light, thereby providing a detectable signature of their presence. Employing covariant coupled-wave framework, we envision waves as phase-insensitive ``luminal moving gratings'' and derive phase-matching conditions articulate such an interaction whilst conserving both energy momentum. Besides preserving directional coupling imposes no...
We remove some ambiguities associated with the coupled mode description of light propagation in fiber Bragg gratings (FBC's). show, particular, that different methods employed literature lead to physically distinct results. The significant distinctions are discussed both for interferometric systems and intensity-only spectral measurements. Analysis reflection spectrum a suitably designed double-grating structure is shown result novel form hole, similar well-known effect derived from...
We discuss the use of Mueller matrices for characterizing reflecting properties beetles, including matching patterns significant elements to specific cuticular architectures. In case illumination by natural light, parameters reflected light are related first column matrix. The green and red beetle Stephanorrhina guttata is shown be a narrowband polarization-preserving reflector apart from depolarizing white patches, Calloodes grayanus left-circular reflector, gold Anoplognathus parvulus...
The Poynting vector is an invaluable tool for analysing electromagnetic problems. However, even a rigorous stress–energy tensor approach can still leave us with the question: it best defined as E × H or D B? Typical treatments provide yet another perspective: they regard B appropriate definition, because and are taken to be fundamental fields. astute reader will notice fourth possible combination of fields, i.e. H. Faced this diverse selection, we have decided treat each flux on its merits,...
We showcase the impact of almost-periodicity on parametric amplification associated with first-order momentum gap in photonic time-crystals time-varying permittivity. Utilizing a vectorial coupled-wave theory approach, we rigorously analyze scattering by temporal slab considered medium. pinpoint critical regime wherein flaws material tuning paradoxically enhance due to coupling fewer, broader modes, resulting higher and pulselike envelope. Additionally, demonstrate that intensity...
A simulation has been carried out on N coupled lasers. complex coupling parameter used, thus accounting for the phase of interacting fields; turns to be a key that determines dynamics system. Nonlocal is considered, in which cooperative effects oscillator community are emphasized. It shown achieving phase-locked or synchronized state crucially dependent statistical width distribution cavity resonance frequencies and also mechanism.
Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text M. McCall and K. Weir, "Bragg Gratings, Photosensitivity, Poling in Glass Waveguides," Bragg Waveguides, T. Erdogan, E. Friebele, R. Kashyap, eds., Vol. 33 of OSA Trends Optics Photonics Series (Optica Publishing Group, 1999), paper BA6. Export BibTex Endnote (RIS) HTML Plain alert Save article
Spacetime or `event' cloaking was recently introduced as a concept, and the theoretical design for such cloak presented illumination by electromagnetic waves [McCall, Favaro, Kinsler, Boardman 2011]. Here we describe how event cloaks can be designed simple wave systems, using either an approximate `speed cloak' method, exact full-wave one. Further, discuss in detail many of implications spacetime transformation devices, covering their (usually) directional nature, distortions (as opposed to...
An author was omitted from the list in reference [7]. The correct is: McCall M W and Censor D 2007 Relativity mathematical tools: waves moving media Am. J. Phys. 75 1134--40.
Invisibility, a long sought-for speculation in science fiction, has been turned into reality the laboratory through use of theoretical technique called Transformation Optics. The principles transformation optics show that any desired smooth deformation electromagnetic field can be implemented exactly by an appropriately engineered metamaterial. All demonstrations cloaking to date have had limitations, however, reflecting our technological inability implement algorithm exactly. However,...