Topic
Near and far field
About: Near and far field is a research topic. Over the lifetime, 15922 publications have been published within this topic receiving 220571 citations.
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TL;DR: Modeling of the field distribution on resonance provides evidence of strong localization of the electric field at the interface and substantial power flow along the interface, thus verifying the surface plasmon–like nature of the mode.
Abstract: We studied the microwave reflectivity of a structured, near perfectly conducting substrate that was designed to verify the existence of a theoretically proposed new class of surface mode. Measurements of the mode's dispersion curve show that it correctly approaches the predicted asymptotic frequency; the curve also agrees well with that derived from a computer simulation. Modeling of the field distribution on resonance provides evidence of strong localization of the electric field at the interface and substantial power flow along the interface, thus verifying the surface plasmon-like nature of the mode.
765 citations
TL;DR: It is experimentally demonstrated that surface phonon polaritons dramatically enhance energy transfer between two surfaces at small gaps by measuring radiation heat transfer between a microsphere and a flat surface down to 30 nm separation.
Abstract: Surface phonon polaritons are electromagnetic waves that propagate along the interfaces of polar dielectrics and exhibit a large local-field enhancement near the interfaces at infrared frequencies. Theoretical calculations show that such surface waves can lead to breakdown of the Planck’s blackbody radiation law in the near field. Here, we experimentally demonstrate that surface phonon polaritons dramatically enhance energy transfer between two surfaces at small gaps by measuring radiation heat transfer between a microsphere and a flat surface down to 30 nm separation. The corresponding heat transfer coefficients at nanoscale gaps are 3 orders of magnitude larger than that of the blackbody radiation limit. The high energy flux can be exploited to develop new radiative cooling and thermophotovoltaic technologies.
729 citations
TL;DR: In this paper, the authors exploit the dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal's output surface with a compressed angular spectrum, resulting in a ''magnified'' image.
Abstract: Here we suggest and explore theoretically an idea for a far-field scanless optical microscopy with a subdiffraction resolution. We exploit the special dispersion characteristics of an anisotropic metamaterial crystal that is obliquely cut at its output plane, or has a curved output surface, in order to map the input field distribution onto the crystal's output surface with a compressed angular spectrum, resulting in a ``magnified'' image. This can provide a far-field imaging system with a resolution beyond the diffraction limits while no scanning is needed.
705 citations
TL;DR: An approach for subwavelength focusing of microwaves using both a time-reversal mirrorplaced in the far field and a random distribution of scatterers placed in the near field of the focusing point is presented.
Abstract: We present an approach for subwavelength focusing of microwaves using both a time-reversal mirror placed in the far field and a random distribution of scatterers placed in the near field of the focusing point. The far-field time-reversal mirror is used to build the time-reversed wave field, which interacts with the random medium to regenerate not only the propagating waves but also the evanescent waves required to refocus below the diffraction limit. Focal spots as small as one-thirtieth of a wavelength are described. We present one example of an application to telecommunications, which shows enhancement of the information transmission rate by a factor of 3.
678 citations