Browsing by Author "Usik, P. V."

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Open Access
Defect-mode-like transmission and localization of light in photonic crystals without defects
(The American Physical Society, 2010-10-29) Serebryannikov, A. E.; Özbay, Ekmel; Usik, P. V.
It is shown that far- and near-field effects, which are similar to those arising in transmission through finite-thickness photonic crystals (PCs) with structural defects, can be obtained in the conventional defect-free dielectric square-lattice PCs. Multiple narrow peaks of total transmission can appear within a frequency range, where the noncircular isofrequency dispersion contours of one type are quickly transformed for a higher-order Floquet-Bloch wave to the noncircular contours of the other type, leading to a frequency-domain passband being very narrow within a certain range of variation of the angles of incidence. In this regime, the mirror reflectance of the equivalent Fabry-Pérot resonator takes rather large values, which correspond to large values of Q factor and group index of refraction, strong field localization, and good isolation of the transmission peaks from each other. In some examples presented, Q factor exceeds 104. © 2010 The American Physical Society.
Open Access
Diffraction inspired unidirectional and bidirectional beam splitting in defect-containing photonic structures without interface corrugations
(American Institute of Physics Inc., 2016) Colak, E.; Serebryannikov, A. E.; Usik, P. V.; Özbay, Ekmel
It is shown that strong diffractions and related dual-beam splitting can be obtained at transmission through the nonsymmetric structures that represent two slabs of photonic crystal (PhC) separated by a single coupled-cavity type defect layer, while there are no grating-like corrugations at the interfaces. The basic operation regimes include unidirectional and bidirectional splitting that occur due to the dominant contribution of the first positive and first negative diffraction orders to the transmission, which is typically connected with different manifestations of the asymmetric transmission phenomenon. Being the main component of the resulting transmission mechanism, diffractions appear owing to the effect exerted by the defect layer that works like an embedded diffractive element. Two mechanisms can co-exist in one structure, which differ, among others, in that whether dispersion allows coupling of zero order to a wave propagating in the regular, i.e., defect-free PhC segments or not. The possibility of strong diffractions and efficient splitting related to it strongly depend on the dispersion properties of the Floquet-Bloch modes of the PhC. Existence of one of the studied transmission scenarios is not affected by location of the defect layer.
Open Access
Multifrequency spatial filtering: a general property of two-dimensional photonic crystals
(Elsevier, 2016) Serebryannikov, A. E.; Colak, E.; Petrov, A.; Usik, P. V.; Özbay, Ekmel
Spatial filtering, an analog of frequency-domain filtering that can be obtained in the incidence angle domain at a fixed frequency is studied in the transmission mode for slabs of two-dimensional rod-type photonic crystals. In the present paper, the emphasis is put on the demonstration of the possibility to obtain various regimes of spatial filtering, i.e., band-stop, band-pass, and low-pass filtering in different frequency ranges in one simple configuration. The operation is based on the use of several Floquet-Bloch modes with appropriate dispersion properties, so that such one or two co-existing mode(s) contribute to the forming of a proper filter characteristic within each specific frequency range. It is shown that high-efficiency transmission and steep switching between pass and stop bands can be obtained in the angle domain for wide ranges of variation of the problem parameters. In particular, by varying the rod-diameter-to-lattice-constant ratio, one attains lots of freedom in the engineering of spatial filters with desired transmission characteristics.
Open Access
Spatial and spatial-frequency filtering using one-dimensional graded-index lattices with defects
(ELSEVIER, 2009) Usik, P. V.; Serebryannikov, A. E.; Özbay, Ekmel
The potential of one-dimensional, periodic, graded-index, isotropic dielectric lattices with defects in multiband spatial and spatial-frequency filtering is studied. It is shown that both narrow- and wide-bandpass filters can be obtained at a proper choice of the number, location, and parameters of the defects placed inside the relatively thin slabs. The peculiarities of achieving multibandness for narrow- and wide-bandpass filters are discussed. Multiband narrow-bandpass filtering is closely related to the transmission features that are associated with Fabry-Pérot resonators with semitransparent planar mirrors. Correspondingly, the observed transmission can be interpreted in terms of the equivalent parameters of such resonators. In particular, it is shown that the resonators filled with an ultralow-index medium can be mimicked, so that defect-mode angle-domain spectrum can be rarefied at large angles of incidence. The obtained results are also expected to be applicable for prediction of the angle-domain behavior of transmission in case of piecewise-homogeneous multilayers.