- 标题
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- 实验方案
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Investigations of properties of opal-like photonic crystals using combined methods
摘要： We propose a technique that combines atomic force microscopy, optical spectrophotometry and di?raction method for characterization of photonic crystals. These materials are promising for the creation of various devices, as well as for the observation of new e?ects due to their unique properties. Photonic crystals were synthesized by self-assembly of colloidal silica particles with low deviation in size. It is shown that the developed technique allows to increase the accuracy of determining the parameters of the photonic crystal.
关键词： diffraction method,photonic crystals,self-assembly,colloidal silica particles,atomic force microscopy,optical spectrophotometry
更新于2025-09-09 09:28:46
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Magneto-optical properties of asymmetric one-dimensional magneto-photonic crystals
摘要： We analytically investigate the magneto-optical properties of asymmetric one-dimensional magneto-photonic crystals (MPCs) by using our previously presented coupled mode description. We show that an MPC with one magnetic defect, placed asymmetrically, provides the same number of degrees of freedom as a symmetric double-defect MPC. Consequently, an asymmetric single-defect MPC allows arbitrary transmittance and Faraday rotation at the central frequency, just as a symmetric double-defect MPC, and hence a desired performance can be obtained by the more compact single-defect structure. However, the possible ranges of performance are more restricted than the possible ranges of a double-defect MPC. We present the synthesis relations to design the single-defect MPC. In a similar manner, we show that an asymmetric double-defect MPC provides more degrees of freedom than either a symmetric double-defect or an asymmetric single-defect MPC. The excessive degree allows us to design a more compact MPC than the symmetric double-defect MPCs for a desirable central frequency performance, in the wide possible range that double-defect structures provide.
关键词： Faraday rotation,Synthesis,Magneto-photonic crystals,Coupled mode theory
更新于2025-09-09 09:28:46
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Synthesis of Silica Microspheres—Inspired by the Formation of Ice Crystals—With High Homogeneous Particle Sizes and Their Applications in Photonic Crystals
摘要： Silica microspheres (SMs) must possess the performances of desirable monodispersity, narrow particle size distribution, and high sphericity for preparing photonic crystals (PCs) and other materials such as microspheres reference material, etc. We have adopted the techniques of increasing reactant concentration and raising the temperature to improve the synthesis rate of SMs, gaining inspiration from the formation mechanism of ice crystals. SMs with uniform particle sizes (polydispersity index less than 0.05) and good spherical features were fabricated through homogeneous nucleation. The mathematical relationship between particle sizes of SMs and reactant concentrations is further fitted. High accuracy of the regression equation is verified by an F-test and verification experiment. Highly ordered PCs (the stacking fault is about 1.5%, and the point defect is about 10?3) with dense stacked opal structures have been obtained by self-assembly of SMs. In addition, highly ordered PCs (the stacking fault is about 3%, and the point defect is about 10?3) with non-dense packed opal structure and inverse opal structure were successfully prepared. PCs of inverse opal structure were used to examine their response characteristics to identify ethanol, exhibiting good performance. Our research may provide significant inspiration for the development of other sorts of microspheres.
关键词： photonic crystals,silica microspheres,homogeneous nucleation,self-assembly
更新于2025-09-09 09:28:46
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Controllable generation of second-harmonic vortex beams through nonlinear supercell grating
摘要： Lithium niobate (LiNbO3) nonlinear photonic crystals have been widely used in nonlinear wave front modulation for the p-phase difference between the second-harmonic (SH) waves from positive and negative domains. Aided by optimizing algorithms, we can control the diffraction patterns of SH vortex beams by designing nonlinear fork gratings with supercell structures in LiNbO3 crystals. In experiment, we demonstrate that the diffraction energies can be equally distributed in each order or concentrated on certain orders, in agreement with theoretical designs. Potential applications include controllable vortex beam generation, nondestructive parallel vortex detection, and so on.
关键词： quantum information processing,Lithium niobate,optical communication,nonlinear photonic crystals,supercell grating,second-harmonic vortex beams,nonlinear optics
更新于2025-09-09 09:28:46
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Bound states in the continuum in a bilayer photonic crystal with TE-TM cross coupling
摘要： Bound states in the continuum (BICs) in photonic crystals represent the unique solutions of wave equations possessing an infinite quality factor. We design a type of bilayer photonic crystal and study the influence of symmetry and coupling between TE and TM polarizations on BICs. The BIC modes possess C3v symmetry in the x-y plane while the mirror-flip symmetry in the z direction is broken, and they provide selective coupling into different layers by varying frequency. The enhanced TE-TM coupling due to broken mirror-flip symmetry in the z direction gives rise to high-Q-factor BIC states with unique spatial characteristics. We show the emergence of such BIC states even in the presence of coupling between the TE- and TM-like modes, which is different from the existing single polarization BIC models. We propose to study BICs in multilayer systems, and the results may be helpful in designing photonic settings to observe and manipulate BICs with various symmetries and polarizations for practical applications.
关键词： High-Q-factor,Bound states in the continuum,Bilayer systems,Photonic crystals,TE-TM coupling
更新于2025-09-09 09:28:46
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Fano Resonances for Realizing Compact and Low Energy Consumption Photonic Switches
摘要： We present our recent experimental work involving nanocavities which enable efficient light-matter interaction in small optical mode volumes. To achieve this, we investigated photonic crystal membrane platforms for designing high-quality (Q) factor nanocavities and efficient planar waveguides. Particularly, we discuss waveguide-nanocavity coupled systems for realization of asymmetric Fano resonances which are characterized by having transmission maximum and minimum in close spectral separation (~ 1 nm) suitable for optical switching applications.
关键词： nonlinear optics,Fano resonances,photonic crystals,all-optical switching
更新于2025-09-09 09:28:46
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Group theoretical route to weakly and strongly protected surface states in 2D and 3D photonic crystals
摘要： Topologically protected surface states in photonic systems, with unique properties such as unidirectional propagation and light con?nement insensitive to thermal or fabrication imperfections, have attracted immense attention over the past ten years. We introduce the notion of weak protection where a topological invariant predicts the existence of surface states in the photonic bulk gap, and strong protection which instead corresponds to the number of glueing points of a surface band with the bulk edges. While strong protection is desired for many key applications such as topologically protected loss-free cavities to boost non-linear interactions, it requires optical reciprocity breaking in two dimensions. We here provide a group theoretical recipe to design weakly protected states on purely dielectric metasurfaces, and genuinely strongly protected states in fully connected 3D photonic crystals. Both design principles can be readily realized by current direct manufacturing techniques, such as electron beam lithography and direct laser writing, respectively.
关键词： topologically protected surface states,strong protection,photonic crystals,group theory,weak protection
更新于2025-09-09 09:28:46
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Study of Raman Spectra of Pb<inf>3</inf>(P<inf>0.5</inf> V<inf>0.5</inf>O<inf>4</inf>)<inf>2</inf>Crystallized in Nanoscale Opal Pores
摘要： The results of Raman spectra investigation of dielectric Pb3(Р0.5V0.5О4)2 crystallized in pores of synthetic opal are presented. The comparative analysis of these spectra with Raman spectra of Pb3(Р0.5V0.5О4)2 in the monocrystalline state is carried out. Due to fitting o the spectra it was possible to reveal the changes in position of the spectral lines and their half-widths. It was shown that these effects may be caused by changing in the lengths of bonds inside the Pb3(Р0.5V0.5О4)2 molecule as a result of crystallization in nano-sized pores of synthetic opal.
关键词： synthetic opals,Raman spectra,lead phosphate-vanadate,photonic crystals,nanocrystals
更新于2025-09-09 09:28:46
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Applied Nanophotonics || Lightwaves in restricted geometries
摘要： The subject of this chapter is propagation, reflection, and evanescence of electromagnetic waves in continuous and complex media and structures to introduce the basics of wave optics and its implementation in novel nanophotonic conceptions. Electromagnetic waves propagate in a medium with positive permittivity, reflect at every permittivity step, and evanesce in a metal featuring negative permittivity. Combination of different dielectrics allows for wave confinement, tunneling, and energy storage, and gives rise to the photonic crystals notion. Combination of a metal with a dielectric material in nanostructures allows for optical material design like stained glass and very high local concentration of incident field to arrive at the notion of nanoplasmonics and optical antennas.
关键词： wave optics,photonic crystals,optical antennas,nanophotonics,electromagnetic waves,nanoplasmonics
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Lausanne (2018.7.29-2018.8.2)] 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Energy-Efficient Silicon Photonic Crystal Nanocavity Modulator Driven by Indium Oxide Gate
摘要： We report an ultra-energy-efficient silicon photonic crystal nanocavity modulator driven by a metal-oxide-semiconductor (MOS) capacitor consisting of In2O3/HfO2/p-Si stacked film, which yields an ultra-high tuning efficiency of 250pm/V, a strong modulation strength of 4dB/V by a 0.35μm electrode, and a low energy consumption of 3fJ/bit.
关键词： micro-cavity,photonic crystals,waveguide modulators
更新于2025-09-09 09:28:46