- 标题
- 摘要
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- 实验方案
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The Sensing Applications in U-Shape Structure Based on Dual Transparency Windows
摘要： We have researched a U-shape structure that consists of three vertical cavities coupled with bus wave-guide. The theoretical results based on the coupled mode theory are consistent with simulation results. We demonstrate that the interaction among two bright and one dark modes lead to dual plasmon induced transparency. Meanwhile, it is found that the lateral displacement S plays an important role in the transmission property, and the transmission dip with different transmittance in various lateral displacement S has been explained theoretically. Moreover, the nano sensor has a sensitivity of 1225 nm shift per refractive index unit, and the ?gure of merit is up to 62.5. The proposed structure has the advantages of simple and compact structure, easy fabrication, and the ultra-compact structure holds great potential to the control of light in highly integrated optical circuits and nano sensor.
关键词： Surface plasmons,nano sensors,coupled mode theory
更新于2025-09-23 15:23:52
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Approximate photonic bandgaps of dielectric-magnetic one-dimensional photonic crystals
摘要： The one dimensional photonic crystals (1DPCs) that have both the permittivity and permeability varying periodically along the same direction are analyzed theoretically using the coupled-mode theory. The approximate band edge frequencies, center frequencies, and the bandgaps are derived for the axial propagation. The results are elegant generalization of the corresponding results of the dielectric 1DPCs. The approximate bandedge frequencies obtained were found to have good agreement with those obtained by the transfer matrix method.
关键词： One-dimensional photonic crystal,Coupled-mode theory,Dielectric-magnetic photonic crystal
更新于2025-09-23 15:21:21
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Fano-resonant Excitations of Generalized Optical Spin Waves
摘要： While chiral materials possess spin-form wave functions as their eigenmodes, optical spin excitations cannot be obtained solely in chiral materials due to a lack of spin impedances. To date, spin excitation has generally been induced through non-conservative methods, such as circular dichroism or magneto-optical effects. In this chapter, we describe a conservative approach to optical spin excitation and control based on the spin-dependent appearance of Fano resonance. Starting from the development of the spin-form temporal coupled mode theory for 2D and 3D chiral resonances, the origin of the spin-Fano interactions is demonstrated in terms of the link between the spin eigenmodes in the polarization domain and anti-symmetric Fano resonances in the spectral domain. By comparing this spin-dependent Fano-resonant system with other optical spin materials, such as chiral, circular dichroic, and birefringent media, we discuss the impact of our results toward the realization of optical spintronics, such as applications of highly selective spin switching and unpolarized spinning operations.
关键词： Fano resonance,chiral materials,temporal coupled mode theory,optical spin,spintronics
更新于2025-09-23 15:21:21
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Coupled Mode Demonstration of Slow-Light Plasmonic Sensor Based on Metasurface at Near-Infrared Region
摘要： In this paper, we theoretically and numerically reported a dual plasmon-induced transparency and the relevant sensing property in a multi-cross metasurface by the coupled mode analysis. A phase coupling model was established to characterize the optical response of this plasmonic sensor. It was found that the transparency windows were sensitive to the resonance mode of each metal strip, which was well demonstrated by the theoretical model. Both the sensing property and the slow light in this structure were discussed. A high figure of merit of 223 and sensitivity of 850 nm/RIU were achieved. In addition, the 1170-nm near-infrared light can be slowed down by nearly two order of magnitude with group delay of 0.45 ps in this sensor. These results may provide guidance for light-matter interaction-enhanced slow-light sensor and integrated optical circuit design.
关键词： Plasmon-induced transparency,Plasmonic sensor,Metasurface,Slow light,Coupled mode theory
更新于2025-09-23 15:21:01
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A nanosensor with ultra-high FOM based on tunable malleable multiple Fano resonances in a waveguide coupled isosceles triangular resonator
摘要： A simple plasmonic structure, which is made up of a metal baffle in the middle of the metal–insulator–metal (MIM) waveguide coupled with an isosceles triangular cavity, is reported to achieve triple Fano resonances. These Fano resonances are numerically calculated by the finite element method (FEM). Besides, the multimode interference coupled mode theory (MICMT) and the standing wave theory are used for analyzing the Fano resonances phenomenon. On the one hand, these three Fano resonances can be independently tuned by adjusting the structural parameters, which makes the design of highly integrated photonic circuits more flexible. On the other hand, the proposed structure is well malleable and can be easily extended to a quintuple Fano system by introducing a ring resonator. Furthermore, the suggested structure can act as a high efficient refractive index (RI) sensor, yielding a great sensitivity of 1200 nm/RIU and a ultra-high maximal figure of merit (FOM) value of 3.0 × 106. Comparing with other similar sensors, our structure has relatively good sensitivity and it is superior to other structures in the maximal FOM, which obviously demonstrates its excellent nano-sensing performance.
关键词： Multiple Fano resonances,Multimode interference coupled mode theory (MICMT),Refractive index (RI) sensor,Ultra-high FOM,Surface plasmon polaritons (SPPs)
更新于2025-09-23 15:21:01
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Plasmonics Induced Multifunction Optical Device via Hoof-Shaped Subwavelength Structure
摘要： The electromagnetic spectrum includes the frequency range (spectrum) of electromagnetic radiation and its corresponding wavelength and energy. Due to the unique properties of different frequency ranges of the electromagnetic spectrum, a series of functional devices working in each frequency rang have been proposed. Here, we propose a periodic subwavelength hoof-shaped structure array, which contains a variety of geometric configurations, including U-shaped and rectangle structures. The results show that the enhanced optical transmission (EOT) effect of the surface plasmon excited by the hoof-shaped structure is highly sensitive to the polarization of the incident light, which leads to the peak’s location shift and the amplitude intensity variety of transmission peaks of U-shaped structure in the case of coupling based on the surface plasmon of rectangle structure. In addition, take advantage of the EOT effect realized in the periodic hoof-shaped structure array, we propose a multifunctional plasmon optical device in the infrared range. By adjusting the polarization angle of the incident light, the functions of the optical splitter in the near-infrared range and the optical switch in the mid-infrared range are realized. Moreover, with the changes of the polarization angle, different proportions of optical intensities split are realized. The device has theoretically confirmed the feasibility of designing multifunctional integrated devices through a hoof-shaped-based metamaterial nanostructure, which provides a broad prospect for the extensive use of multiple physical mechanisms in the future to achieve numerous functions in simple nanostructures.
关键词： interaction between light and metallic film,plasmonic optical device,enhanced optical transmission,coupled mode theory
更新于2025-09-23 15:21:01
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Multiport optical power splitter design based on coupled-mode theory
摘要： We proposed a multiport T-shaped 1 x 8 balanced optical power splitter design based on asymmetric vertical silicon slot waveguides working on the principle of coupled-mode theory (CMT). The scheme of the power splitter is unique which offers strong field confinement of TE-polarized light and delivers the light to four ports each on two opposite side of the chip. By shifting the slot towards the outer sideline of the bend, the bending losses are reduced to 80% as compared to standard symmetric slot waveguide.
关键词： coupled-mode theory,asymmetric vertical silicon slot waveguides,bending losses,TE-polarized light,optical power splitter
更新于2025-09-23 15:19:57
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Dispersion properties of uniform trapezoidal optical waveguides
摘要： A method for calculation of the propagation constant of guided modes in the optical waveguides with trapezoidal cross-sections is proposed. The method enables to calculate a propagation constant correction factor that arises due to perturbations of the cross-section of a reference rectangular waveguide. The correction factor is analytically calculated within the framework of the coupled-mode theory. A re?ned form of the coupling coe?cient is obtained owing to the application of a concept of e?ective excitation sources and accurate account of boundary conditions. An impact of the waveguide cross-section shape on its dispersion properties is analysed. The necessity to take into account the proposed form of the coupling coe?cient is demonstrated by comparison of the simulation results with other methods of dispersion calculation.
关键词： coupled-mode theory,optical waveguides,trapezoidal cross-sections,dispersion properties,propagation constant
更新于2025-09-23 15:19:57
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High reflection from a one-dimensional array of graphene nanoribbons
摘要： We show that up to 90% reflectivity can be achieved by using guided plasmonic resonances in a one-dimensional periodic array of plasmonic nanoribbon. In general, to achieve strong reflection from a guided resonance system requires one to operate in the strongly over-coupled regime where the radiative decay rate dominates over the intrinsic loss rate of the resonances. Using an argument similar to what has been previous used to derive the Chu-Harrington limit for antennas, we show theoretically that there is no intrinsic limit for the radiative decay rate even when the system has an atomic scale thickness, in contrast to the existence of such limits on antennas. We also show that the current distribution due to plasmonic resonance can be designed to achieve very high external radiative rate. Our results show that high reflectivity can be achieved in an atomically-thin graphene layer, pointing to a new opportunity for creating atomically-thin optical devices.
关键词： coupled-mode theory,graphene,Chu-Harrington limit,plasmonics
更新于2025-09-19 17:15:36
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Dynamics and transport properties of Floquet topological edge modes in coupled photonic waveguides
摘要： We study theoretically the Floquet edge states in a photonic analog of the driven Su-Schrieffer-Heeger model implemented by an array of identical single-mode dielectric waveguides, where the time-dependent driving is modeled by periodically bended waveguides. We combine the coupled-mode theory with the Floquet-Bloch analysis and within this framework determine a band structure of the periodic system. We develop a theoretical approach for calculation of the edge states in semi-infinite systems and investigate their topological properties. In particular, we explore the dynamics of the 0- and π-edge states which reveal profound differences depending on their topological phase. To verify our observations, we simulate the power transport along the end of such a waveguide array and show that its spectra can be assigned to the excitation of the edge modes. The results obtained indicate that driving-induced topological properties of the edge modes can be exploited in controlling flow of light in periodically driven photonic structures and may provide insight into Floquet engineering of the realistic photonic systems.
关键词： photonic analog,coupled-mode theory,dielectric waveguides,Floquet edge states,power transport,Floquet engineering,topological properties,Su-Schrieffer-Heeger model,Floquet-Bloch analysis
更新于2025-09-19 17:13:59