75 research outputs found
Transmission enhancement in loss-gain multilayers by resonant suppression of reflection
Using the transfer-matrix approach and solving time-domain differential
equations, we analyze the loss compensation mechanism in multilayer systems
composed of an absorbing transparent conductive oxide and dielectric doped with
an active material. We reveal also another regime with the possibility of
enhanced transmission with suppressed reflection originating from the resonant
properties of the multilayers. For obliquely incident and evanescent waves,
such enhanced transmission under suppressed reflection turns into the
reflectionless regime, which is similar to that observed in the PT-symmetric
structures, but does not require PT symmetry. We infer that the reflectionless
transmission is due to the full loss compensation at the resonant wavelengths
of the multilayers.Comment: 12 pages, 10 figure
Invisibility devices with realistic material parameters:УСТРОЙСТВА НЕВИДИМОСТИ С УЧЕТОМ РЕАЛЬНЫХ МАТЕРИАЛЬНЫХ ПАРАМЕТРОВ СРЕД
Pseudocanalization regime for magnetic dark-field hyperlens
Hyperbolic metamaterials (HMMs) are the cornerstone of the hyperlens, which
brings the superresolution effect from the near-field to the far-field zone.
For effective application of the hyperlens it should operate in so-called
canalization regime, when the phase advancement of the propagating fields is
maximally supressed, and thus field broadening is minimized. For conventional
hyperlenses it is relatively straightforward to achieve canalization by tuning
the anisotropic permittivity tensor. However, for a dark-field hyperlens
designed to image weak scatterers by filtering out background radiation
(dark-field regime) this approach is not viable, because design requirements
for such filtering and elimination of phase advancement i.e. canalization, are
mutually exclusive. Here we propose the use of magnetic (-positive and
negative) HMMs to achieve phase cancellation at the output equivalent to the
performance of a HMM in the canalized regime. The proposed structure offers
additional flexibility over simple HMMs in tuning light propagation. We show
that in this ``pseudocanalizing'' configuration quality of an image is
comparable to a conventional hyperlens, while the desired filtering of the
incident illumination associated with the dark-field hyperlens is preserved
Asymmetric transmission in planar chiral split-ring metamaterials: Microscopic Lorentz-theory approach
The electronic Lorentz theory is employed to explain the optical properties of planar split-ring metamaterials.
Starting from the dynamics of individual free carriers, the electromagnetic response of an individual split-ring
meta-atom is determined, and the effective permittivity tensor of the metamaterial is calculated for normal
incidence of light. Whenever the split ring lacks in-plane mirror symmetry, the corresponding permittivity
tensor has a crystallographic structure of an elliptically dichroic medium, and the metamaterial exhibits optical
properties of planar chiral structures. Its transmission spectra are different for right-handed versus left-handed
circular polarization of the incident wave, so the structure changes its transmittance when the direction of
incidence is reversed. The magnitude of this change is shown to be related to the geometric parameters of the split
ring. The proposed approach can be generalized to a wide variety of metal-dielectric metamaterial geometries
Magnetic field concentration with coaxial silicon nanocylinders in the optical spectral range
Resonant magnetic energy accumulation is theoretically investigated in the optical and near-infrared regions. It is demonstrated that the silicon nanocylinders with and without coaxial through holes can be used for the control and manipulation of optical magnetic fields, providing up to 26-fold enhancement of these fields for the considered system. Magnetic field distributions and dependence on the parameters of nanocylinders are revealed at the wavelengths of magnetic dipole and quadrupole resonances responsible for the enhancement. The obtained results can be applied, for example, to designing nanoantennas for the detection of atoms with magnetic optical transitions
Light dynamics in PT-symmetric multilayers: phase transition, nonreciprocity, and propagation direction locking
Semangat ekonomi pesantren salaf: telaah sosiologis terhadap perekonomian Pondok Pesantren Sidogiri
Beberapa persoalan yang dikaji dalam skripsi ini (1) Bagaimana bentuk konkrit spirit kapitalisme dalam pesantren salaf? (2) Apa yang memotifasi sidogiri bergerak da1atn bidang ekonomi? (3) Kenapa semangat kapitalisme terjadi pada lembaga salafiah? Adapun tujuan penelitian ini yang pertama, mendapat kebenaran tentang pengaruh teks suci terhadap perilaku ekonomi, yang kedua mengetahui sejauh mana nilai-nilai teks membentuk perilaku ekonomi dan yang terakhir menjelaskan peran ekonomi pesantren dalam menopang kehidupan pesantren. Dengan pisau analisa action theory Weber, diharpakan mampu memberikan suatu kesimpulan yang utuh tentang gejala sosial di atas. Teori tindakan digunakan oleh Weber sebagai kerangka konsepstual untuk memahami kenyataan dalam masyarakat. Weber beranggapan bahwa yang benar-benar riil dalam masyarakat adalah individu. Bagaimana hal ini bisa paradoks, satu sisi subyek kajiannya adalah lembaga namun pada sisi yang lain subyek analisanya adalah individu?. Melalui proses yang panjang dibagian akhir telah desebutkan bahwa spirit ekonomi kapitalisme pesantren salaf bukan representasi dari ekonomi sistem dunia, hal ini karena etika ekonomi Sidogiri tetap berpijak pada teks suci sebagai landasan berpikir dan bertindaknya. Artinya teks menjadi pedoman dasar dalam menata perekonomian Pesantren
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