Transformation optics

About: Transformation optics is a research topic. Over the lifetime, 2687 publications have been published within this topic receiving 102378 citations.

Nearly cloaking the full maxwell equations

Abstract: The approximate cloaking is investigated for time-harmonic Maxwell's equations via the approach of transformation optics. The problem is reduced to certain boundary effect estimates due to an inho- mogeneous electromagnetic inclusion with an asymptotically small sup- port but an arbitrary content enclosed by a thin high-conducting layer. Sharp estimates are established in terms of the asymptotic parameter, which are independent of the material tensors of the small electromag- netic inclusion. The result implies that the 'blow-up-a-small-region' con- struction via the transformation optics approach yields a near-cloak for the electromagnetic waves. A novelty lies in the fact that the geometry of the cloaking construction of this work can be very general. Moreover, by incorporating the conducting layer developed in the present paper right between the cloaked region and the cloaking region, arbitrary electro- magnetic contents can be nearly cloaked. Our mathematical technique extends the general one developed in (30) for nearly cloaking scalar op- tics. In order to investigate the approximate electromagnetic cloaking for general geometries with arbitrary cloaked contents, new techniques and analysis tools must be developed for this more challenging vector optics case.

Field approach in the transformation optics concept

Abstract: An alternative, fleld-based formulation of transformation optics is proposed. Field transformations are expressed in the language of boundary conditions for the electromagnetic flelds facilitated through the introduction of generalized potential functions. It is shown that the fleld-based approach is equivalent to the conventional coordinate-transformation approach but is preferable when looking for speciflc fleld distribution. A set of example devices such as invisibility cloaks, concentrators, rotators, and transformation optics lenses capable of creating light beams with predetermined fleld distribution (e.g., Gaussian and sinusoidal) is studied to validate the efiectiveness of the fleld-based formulation. As for the boundary conditions for the cloaked region the absence of the normal component of the Poynting vector is justifled. In the frames of the fleld- based approach the physical reasons behind inflnite components (singularities) of the material parameters of transformation optics devices are straightforwardly revealed.

Tight-binding analysis of coupling effects in metamaterials

Abstract: We established a generalized tight-binding method (TBM) to study the coupling effects in metamaterials. All parameters involved in our theory can be calculated from first principles, and the theory is applicable to general photonic systems with both dielectric and magnetic materials. As an illustration, we applied the theory to study the cutoff waveguides loaded with resonant electric/magnetic metamaterials. We not only accurately computed the coupling strengths between two resonant metamaterials, but also revealed a number of interesting coupling-induced phenomena. Microwave experiments and full-wave numerical simulations were performed to successfully verify all predictions drawn from the TBM.

Mode Analysis of Phase-Constant Nonreciprocity in Ferrite-Embedded CRLH Metamaterials

Abstract: SUMMARY Phase-nonreciprocal e-negative and CRLH metamaterials are analyzed using a new approach in which field analysis and transmission line model are combined. The examined one-dimensional nonreciprocal metamaterials are composed of a ferrite-embedded microstrip line periodically loaded with shunt stubs. In the present approach, the phase constant nonreciprocity is analytically estimated and formulated under the assumption of operating frequency far above the ferromagnetic resonant frequency. The present approach gives a good explanation to the phenomenon in terms of ferromagnetic properties of the ferrite and asymmetric geometry of the metamaterial structure, showing a good agreement with numerical simulations and experiment.

Nonlocal effects in temporal metamaterials

Abstract: Abstract Nonlocality is a fundamental concept in photonics. For instance, nonlocal wave-matter interactions in spatially modulated metamaterials enable novel effects, such as giant electromagnetic chirality, artificial magnetism, and negative refraction. Here, we investigate the effects induced by spatial nonlocality in temporal metamaterials, i.e., media with a dielectric permittivity rapidly modulated in time. Via a rigorous multiscale approach, we introduce a general and compact formalism for the nonlocal effective medium theory of temporally periodic metamaterials. In particular, we study two scenarios: (i) a periodic temporal modulation, and (ii) a temporal boundary where the permittivity is abruptly changed in time and subject to periodic modulation. We show that these configurations can give rise to peculiar nonlocal effects, and we highlight the similarities and differences with respect to the spatial-metamaterial counterparts. Interestingly, by tailoring the effective boundary wave-matter interactions, we also identify an intriguing configuration for which a temporal metamaterial can perform the first-order derivative of an incident wavepacket. Our theoretical results, backed by full-wave numerical simulations, introduce key physical ingredients that may pave the way for novel applications. By fully exploiting the time-reversal symmetry breaking, nonlocal temporal metamaterials promise a great potential for efficient, tunable optical computing devices.