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Terahertz shifted Fano resonance-induced plasmon-soliton in graphene-plasmonic waveguide with magnetic impurities
摘要： Fano resonance is a quantum effect particularly useful for determining the optical spectra of semiconductor heterostructures and radiation enhancement of semiconductor-based devices. We deal with the nonlinear amplitude equation to find the nonlinear plasmon modes and breather solutions in a magnetic impurities-added graphene-plasmonic waveguide at near and mid-IR frequency range. The results show that the coupling degree between the plamon modes and breather solutions in order to form plasmon-solitons is intensely influenced by the effective nonlinear refraction assigned to the waveguide and also by the Fermi energy; tunable plasmon-solitons can be formed with a lowly required bias voltage. We also deduce that the stable plasmon-solitons and subsequently the most condensed radiative feature with the largest effective propagation length can be obtained at interband transition edge if the resonance of the effective nonlinear refraction is of Fano type. The reason is inferred as the presence of a reversible mechanism caused by the optical doping which in turn bears a successive competition between the diffraction and nonlinearity. Accordingly, we indicate that the Fano resonance- induced plasmon-soliton modes supported by the Co-added graphene-plasmonic waveguide experience a frequency shift up to Δω ? 60 THz in contrast to the plasmon-soliton modes in the pristine graphene-based waveguide. This in turn, proposes a novel technique for the spectroscopy of magnetic impurities-added graphene-dielectric heterostructures. On the other hand, very sensi- tive modulation of the nonlinear response tunable with a low Fermi energy as presented in this study can delineate modern schemes for the next generation graphene plasmonic devices including the nanoscale radiation sources, modulators, biosensors and couplers.
关键词： Fano resonance,Graphene plasmonic waveguide,Plasmon-soliton,Nonlinear refraction,Breather solution,Magnetic impurities
更新于2025-09-23 15:19:57
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A Graphene based bimetallic plasmonic waveguide to increase photorefractive effect
摘要： In this paper, for enhancement of the nonlinear optical properties of photorefractive gain, a novel plasmonic waveguide is proposed. The geometry of the proposed structure is optimized to reach the highest photorefractive gain. The proposed structure is based on bimetallic structure and it includes a graphene layer. It is shown that a strong mode can be coupled to a weak mode by means of photorefractive effect. It is found that comparing with the conventional symmetric and asymmetric metal-insulator-metal plasmonic waveguides, the proposed structure with different metals and a graphene layer with an optimized notch has higher photorefractive gain and longer propagation distance, the distance for which a net photorefractive gain exists. The effect of the crystal thickness and amplitude inputs are also analyzed. It is found that there is an optimum crystal thickness that yields the maximum photorefractive gain.
关键词： asymmetric structure,Photorefractive e?ect,graphene,plasmonic waveguide,photorefractive gain
更新于2025-09-23 15:19:57
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Visualization of subnanometric phonon modes in a plasmonic nano-cavity via ambient tip-enhanced Raman spectroscopy
摘要： Phonons provide information on the physicochemical properties of a crystalline lattice from the material’s vibrational spectrum. Optical phonons, in particular, can be probed at both micrometre and nanometre scales using light-based techniques, such as, micro-Raman and tip-enhanced Raman spectroscopy (TERS), respectively. Selection rules, however, govern the accessibility of the phonons and, hence, the information that can be extracted about the sample. Herein, we simultaneously observe both allowed and forbidden optical phonon modes of defect-free areas in monolayer graphene to study nanometre scale strain variations and plasmonic activation of the Raman peaks, respectively, using our home-built TERS system in ambient. Through TERS imaging, strain variations and nanometre-sized domains down to 5 nm were visualised with a spatial resolution of 0.7 nm. Moreover, such subnanometric con?nement was found to activate not only the D and D’ forbidden phonon modes but also their D + D’ combination mode. With our TERS in ambient system, the full phonon characterisation of defect-free graphene and other 2D nanomaterials is now possible, which will be useful for subnanometre strain analysis and exploring the inherent properties of defect-free materials.
关键词： graphene,plasmonic nano-cavity,tip-enhanced Raman spectroscopy,phonon modes,strain analysis
更新于2025-09-19 17:13:59
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Fano-Resonance in Hybrid Metal-Graphene Metamaterial and Its Application as Mid-Infrared Plasmonic Sensor
摘要： Fano resonances in nanostructures have attracted widespread research interests in the past few years for their potential applications in sensing, switching and nonlinear optics. In this paper, a mid-infrared Fano resonance in a hybrid metal-graphene metamaterial is studied. The hybrid metamaterial consists of a metallic grid enclosing with graphene nanodisks. The Fano resonance arises from the coupling of graphene and metallic plasmonic resonances and it is sharper than plasmonic resonances in pure graphene nanostructures. The resonance strength can be enhanced by increasing the number of graphene layers. The proposed metamaterial can be employed as a high-performance mid-infrared plasmonic sensor with an unprecedented sensitivity of about 7.93 μm/RIU and ?gure of merit (FOM) of about 158.7.
关键词： fano resonance,graphene,plasmonic sensor
更新于2025-09-19 17:13:59
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Ultra-compact integrated graphene plasmonic photodetector with bandwidth above 110 GHz
摘要： Graphene-based photodetectors, taking advantage of the high carrier mobility and broadband absorption in graphene, have recently seen rapid development. However, their performance with respect to responsivity and bandwidth is still limited by the weak light-graphene interaction and large resistance-capacitance product. Here, we demonstrate a waveguide-coupled integrated graphene plasmonic photodetector on a silicon-on-insulator platform. Benefiting from plasmon-enhanced graphene-light interaction and subwavelength confinement of the optical energy, a small-footprint graphene-plasmonic photodetector is achieved working at the telecommunication window, with a large a bandwidth beyond 110 GHz and a high intrinsic responsivity of 360 mA/W. Attributed to the unique electronic band structure of graphene and its ultra-broadband absorption, operational wavelength range extending beyond mid-infrared, and possibly further, can be anticipated. Our results show that the combination of graphene with plasmonic devices has great potential to realize ultra-compact, high-speed optoelectronic devices for graphene-based optical interconnects.
关键词： waveguide,photodetector,graphene,plasmonic
更新于2025-09-12 10:27:22
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Ultra-compact, low-loss Terahertz waveguide based on graphene plasmonic technology
摘要： In order to meet the demand for highly integrated terahertz chips with ultra-low transmission loss, a novel hybrid graphene plasmonic waveguide is proposed, wherein low-index insulators are embedded between a slot-rib (covered by graphene) structure and a high-index dielectric waveguide. This designed waveguide combines the plasmonic response of graphene, energy distribution mechanism of materials with large refractive index difference, and modal properties of hybrid plasmonic waveguide to yield superior waveguiding performance. We achieved 50 times stronger mode confinement along with 5 times smaller propagation loss, as compared to the traditional graphene hybrid plasmonic waveguide operating at 3 THz. Investigation on the influence of modal properties on chemical potential of graphene revealed an active approach to control mode confinement or propagation distance. In addition, owing to the ultra-strong energy confinement of modes, the crosstalk caused by coupling between two parallel waveguides is negligible, which paves the way for realizing ultra-compact, chip-level terahertz devices.
关键词： terahertz communication,graphene,plasmonic waveguide
更新于2025-09-12 10:27:22
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Handbook of Graphene || Graphene Plasmonic: Switching Applications
摘要： This chapter focuses on the graphene plasmonic-based optical switching devices operating in the infrared to terahertz spectrum. Graphene plasmonic due to high strong light–matter interaction and nanoscale size has received significant attention in recent years, as they have found an important role in many areas of optical science and engineering by offering schemes to control electromagnetic fields. Another area of science that has been under the spotlight for the last few years relates to graphene plasmonic metasurface, which is formed of graphene layer packed into a structure. This material exhibits exceptional electronic and optical properties, intriguing many research groups across the world including us. However, our interest is specifically in studying the interaction between electromagnetic waves with surface modes of graphene in multilayer configuration (such as Otto configuration) and switching applications that might follow. In this chapter, relying on theoretical models and numerical simulations, we show that by designing and manipulating optical and electrical properties of graphene such as chemical potential, temperature, scattering rate, as well as incident beam characteristics such as beam width, one can have the structures based on graphene as a good platform for not only infrared optical switching devices but also terahertz switching devices.
关键词： Otto configuration,Graphene plasmonic,graphene conductivity,optical switches,terahertz,metasurface
更新于2025-09-11 14:15:04