二维异质结光子晶体中含近邻点缺陷的弯曲波导的可调谐滤波特性

应用时域有限差分(FDTD)法,对光在二维异质结光子晶体中含两个近邻点缺陷直角弯曲波导的传输特性进行了数值模拟研究。计算结果表明,具有特定本征共振频率的光子晶体微腔(点缺陷),可将在其邻近波导中传播的相同频率成分的光波"引入"到微腔中。"引入"的频率依赖于异质结光子晶体弯曲波导和微腔的参量,从而能够实现调变"引入"频率。通过改变点缺陷周围介质材料(液晶)的折射率或相关介质柱半径,可分别实现约31 nm或12 nm的波长调谐范围。计算结果为光通信中的调谐、上/下载滤波器,提供了一条新的设计思路和依据。     

Magnetic Properties of Layered Ferrimagnetic Structures Based on Gd and Transition 3d Metals

Journal of Experimental and Theoretical Physics - Magnetic properties of layered structures based on transition and rare-earth metals (TMs and REMs) such as Fe and Gd have attracted attention of...     

Phase-Coherent Thermoelectricity in Superconducting Hybrids (Brief Review)

JETP Letters - We review some recent advances in studies of phase-coherent thermoelectric effects in superconducting hybrid structures such as, e.g., Andreev interferometers. We elucidate a number...     

Application of Graphene Composites for Additional Vibration Damping in Smart Structures Based on Piezoelectric Elements

Doklady Physics - A smart-structure variant representing a piecewise homogeneous body composed of elastic and viscoelastic materials and piezoelectric elements the electrodes of which can be...     

Spin Fluctuations and Negative Heat Capacity (Brief Review)

JETP Letters - The problem of negative heat capacity, discussed in a number of theoretical and experimental works dealing with weak itinerant magnets, is studied. A detailed analysis of the heat...     

Study of Fiber Optic Elements Based on a Photoactive Polymer Composition for Sensor Applications

Optics and Spectroscopy - The model of a fiber optic sensor device which operational principle is based on the thermal quenching of luminescence for ambient temperature measurements was...     

Engineering of SERS Substrates Based on Noble Metal Nanomaterials for Chemical and Biomedical Applications

Abstract

Surface-enhanced Raman scattering (SERS) has attracted great interest due to its remarkable enhancement, excellent sensitivity, and the “fingerprinting” ability to produce distinct spectra for detecting various molecules. Noble metal nanomaterials have usually been employed as SERS-active substrates because of their strong SERS enhancement originated from their unique surface plasmon resonance (SPR) properties. Because the SPR property depends on metal material's size, shape, morphology, arrangement, and dielectric environment around metal nanostructures, the key to wider applications of SERS technique is to develop plasmon-resonant structures with novel geometries to enhance Raman signals and to control the periodic ordering of these structures over a large area to obtain reproducible Raman enhancement. This review presents a general view on the theory background of SERS effect and several basic concepts and focuses on recent progress in engineering metallic nanostructures with various morphologies using versatile methods for improving SERS properties. Their potential applications in the field of chemical detection and biological sensing are overviewed.     

Macroscopic Manifestations of Quantum Anomalies in Hydrodynamics (Brief Review)

JETP Letters - Some aspects of the theory of so-called chiral effects in fluids whose constituents are massless fermions in the hydrodynamic approximation are briefly reviewed. The underlying field...     

Generation and Application of Broadband Biphoton Fields (Brief Review)

JETP Letters - Biphoton fields obtained in spontaneous parametric down-conversion are among the main tools of modern quantum optics. Temporal correlations between photons in the pair play a key...     

Photon-Stimulated Transport in a Quantum Point Contact (Brief Review)

JETP Letters - Studies of photon-stimulated transport through a quantum point contact based on a high-mobility two-dimensional electron gas in a GaAs quantum well are reviewed. This review includes...     

A Critical Review of Chemical Vapor-Deposited (CVD) Diamond for Electronic Applications

The objective of this article is to describe the present understanding of the growth, processing, and properties of diamond for electronic applications.     

Analysis and Calculations of Forbidden Regions for Transverse-Electric-Guided Waves in the Three-Layer Planar Waveguide with Photonic Metamaterial

Abstract

In this article, the modal theory was used to analyze transverse electric waves in the three-layer planar waveguide with photonic metamaterial. The formulas for the electric fields of transverse electric modes in this structure have been proposed. There always exist two forbidden regions for transverse electric waves in the three-layer planar waveguide with photonic metamaterial. The complete set of modes of all possible solutions for the transverse electric waves in the three-layer planar waveguide with photonic metamaterial had been analyzed and discussed. Similar processes can be extensively used to predict the propagation characteristics of TM waves in the three-layer planar waveguide with photonic metamaterial. The analytical and numerical results show excellent agreement.     

Plasmon Excitations in Partially Screened Two-Dimensional Electron Systems (Brief Review)

JETP Letters - The latest achievements in the study of the physical properties of plasmon excitations in partially screened two-dimensional electron systems based on AlGaAs/GaAs heterostructures...     

Theory of Nematic Superconductivity in Doped Topological Insulators (Brief Review)

JETP Letters - Theoretical studies of the theory of nematic superconductivity in doped insulators of the Bi2Se3 family have been reviewed. It is experimentally shown that their transition to the...     

Terahertz (THz) Frequency Sources and Antennas - A Brief Review

In this paper we review THz radiation properties, generation methods, and antenna configurations. This paper suggests some new class of antennas that can be used at THz frequency, like optical antennas or Carbon nanotube antennas. THz technology has become attractive due to the low energy content and nonionizing nature of the signal. This property makes them suitable for imaging and sensing applications. But at the same time detection and generation of THz signals has been technologically challenging. This paper presents a comparative study of the generation techniques for THz frequency signals giving emphasis to the some new techniques like Quantum Cascade lasers which has created significant research interest. The main aim for this study is to find out the materials suitable for fabricating THz devices and antennas, a suitable method for generation of high power at THz frequency and an antenna that will make THz communication possible.     

Engineering Computation and Analysis of Enhancing Efficiency for Folded Waveguide TWT in MMW

Large signal operating equations in TWT have been solved by numerical solve method. The relations between interaction efficiency and design parameters in TWT are analyzed. A fast engineering design method of enhancing efficiency for folded waveguide TWT by velocity resynchronization is described. The computation is shown that the efficiency of Ka-band folded waveguide TWT with double taper can be enhanced over twice as original tube. This method of approach is very useful for tube designer.     

Generation of Ultrashort Attosecond and Terahertz Pulses Based on the Collective Spontaneous Emission from a Thin Resonant Medium (Brief Review)

JETP Letters - Our recent theoretical studies of generation of ultrashort pulses based on collective spontaneous emission from a thin resonant medium layer excited by a pair of high-frequency...     

Dynamic Spin Phenomena in Complex Structures Based on Ferromagnetic Metals and Semiconductors (Scientific Summary)

JETP Letters - A brief review of theoretical and experimental studies of spin phenomena in various hybrid structures based on magnetically ordered metals and semiconductors is presented. In...