Research

12 pages, 3297 KiB

Open AccessArticle

Actively Tunable Fano Resonance Based on a Bowtie-Shaped Black Phosphorus Terahertz Sensor

by Yan Huang, Yan Liu, Yao Shao, Genquan Han, Jincheng Zhang and Yue Hao

Nanomaterials 2021, 11(6), 1442; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11061442 - 29 May 2021

Cited by 13 | Viewed by 2657

An ultrasensitive Terahertz (THz) sensor consisting of the sub-wavelength bowtie black phosphorus (BP) and an annular gold (Au) ring is proposed. The interference between the resonance generated by the bowtie BP and the Au ring creates a Fano-type resonance and makes ultrasensitive sensing [...] Read more.

An ultrasensitive Terahertz (THz) sensor consisting of the sub-wavelength bowtie black phosphorus (BP) and an annular gold (Au) ring is proposed. The interference between the resonance generated by the bowtie BP and the Au ring creates a Fano-type resonance and makes ultrasensitive sensing realizable. Firstly, we demonstrate the Fano resonance of the coupled nanostructures by adjusting the geometry dimensions of the Au ring and the Fermi level of BP. Moreover, the Poynting vector distributions of the THz sensor are simulated to analyze the properties of Fano resonance. Importantly, a figure of merit (FOM) value as high as 69.3 is achieved and the proposed Fano resonance sensor shows a maximum sensitivity of 9.3 μm/RIU. Our structure can function as a facile and efficient building block of biochemical nano-sensing application based on Fano resonance at THz frequency. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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10 pages, 2642 KiB

Open AccessArticle

A Low-Threshold Miniaturized Plasmonic Nanowire Laser with High-Reflectivity Metal Mirrors

by Jiahui Zheng, Xin Yan, Wei Wei, Chao Wu, Nickolay Sibirev, Xia Zhang and Xiaomin Ren

Nanomaterials 2020, 10(10), 1928; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10101928 - 27 Sep 2020

Cited by 5 | Viewed by 2240

Abstract

A reflectivity-enhanced hybrid plasmonic GaAs/AlGaAs core-shell nanowire laser is proposed and studied by 3D finite-difference time-domain simulations. The results demonstrate that by introducing thin metal mirrors at both ends, the end facet reflectivity of nanowire is increased by 30–140%, resulting in a much [...] Read more.

A reflectivity-enhanced hybrid plasmonic GaAs/AlGaAs core-shell nanowire laser is proposed and studied by 3D finite-difference time-domain simulations. The results demonstrate that by introducing thin metal mirrors at both ends, the end facet reflectivity of nanowire is increased by 30–140%, resulting in a much stronger optical feedback. Due to the enhanced interaction between the surface charge oscillation and light, the electric field intensity inside the dielectric gap layer increases, resulting in a much lower threshold gain. For a small diameter in the range of 100–150 nm, the threshold gain is significantly reduced to 60–80% that of nanowire without mirrors. Moreover, as the mode energy is mainly concentrated in the gap between the nanowire and metal substrate, the output power maintains >60% that of nanowire without mirrors in the diameter range of 100–150 nm. The low-threshold miniaturized plasmonic nanowire laser with simple processing technology is promising for low-consumption ultra-compact optoelectronic integrated circuits and on-chip communications. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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15 pages, 15633 KiB

Open AccessArticle

Photonic and Thermal Modelling of Microrings in Silicon, Diamond and GaN for Temperature Sensing

by Lukas Max Weituschat, Walter Dickmann, Joaquín Guimbao, Daniel Ramos, Stefanie Kroker and Pablo Aitor Postigo

Nanomaterials 2020, 10(5), 934; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10050934 - 12 May 2020

Cited by 14 | Viewed by 3731

Abstract

Staying in control of delicate processes in the evermore emerging field of micro, nano and quantum-technologies requires suitable devices to measure temperature and temperature flows with high thermal and spatial resolution. In this work, we design optical microring resonators (ORRs) made of different [...] Read more.

Staying in control of delicate processes in the evermore emerging field of micro, nano and quantum-technologies requires suitable devices to measure temperature and temperature flows with high thermal and spatial resolution. In this work, we design optical microring resonators (ORRs) made of different materials (silicon, diamond and gallium nitride) and simulate their temperature behavior using several finite-element methods. We predict the resonance frequencies of the designed devices and their temperature-induced shift (16.8 pm K⁻¹ for diamond, 68.2 pm K⁻¹ for silicon and 30.4 pm K⁻¹ for GaN). In addition, the influence of two-photon-absorption (TPA) and the associated self-heating on the accuracy of the temperature measurement is analysed. The results show that owing to the absence of intrinsic TPA-processes self-heating at resonance is less critical in diamond and GaN than in silicon, with the threshold intensity

I_{th} = α / β

,

α

and

β

being the linear and quadratic absorption coefficients, respectively. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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12 pages, 4688 KiB

Open AccessArticle

Perfect Absorption Efficiency Circular Nanodisk Array Integrated with a Reactive Impedance Surface with High Field Enhancement

by Mohamad Khoirul Anam and Sangjo Choi

Nanomaterials 2020, 10(2), 258; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10020258 - 02 Feb 2020

Cited by 5 | Viewed by 3423

Abstract

Infrared (IR) absorbers based on a metal–insulator–metal (MIM) have been widely investigated due to their high absorption performance and simple structure. However, MIM absorbers based on ultrathin spacers suffer from low field enhancement. In this study, we propose a new MIM absorber structure [...] Read more.

Infrared (IR) absorbers based on a metal–insulator–metal (MIM) have been widely investigated due to their high absorption performance and simple structure. However, MIM absorbers based on ultrathin spacers suffer from low field enhancement. In this study, we propose a new MIM absorber structure to overcome this drawback. The proposed absorber utilizes a reactive impedance surface (RIS) to boost field enhancement without an ultrathin spacer and maintains near-perfect absorption by impedance matching with the vacuum. The RIS is a metallic patch array on a grounded dielectric substrate that can change its surface impedance, unlike conventional metallic reflectors. The final circular nanodisk array mounted on the optimum RIS offers an electric field enhancement factor of 180 with nearly perfect absorption of 98% at 230 THz. The proposed absorber exhibits robust performance even with a change in polarization of the incident wave. The RIS-integrated MIM absorber can be used to enhance the sensitivity of a local surface plasmon resonance (LSPR) sensor and surface-enhanced IR spectroscopy. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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9 pages, 1775 KiB

Open AccessArticle

Vortex Beam Encoded All-Optical Logic Gates Based on Nano-Ring Plasmonic Antennas

by Houquan Liu, Hongchang Deng, Shijie Deng, Chuanxin Teng, Ming Chen and Libo Yuan

Nanomaterials 2019, 9(12), 1649; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9121649 - 20 Nov 2019

Cited by 5 | Viewed by 2761

Abstract

Vortex beam encoded all-optical logic gates are suggested to be very important in future information processing. However, within current logic devices, only a few are encoded by using vortex beams and, in these devices, some space optical elements with big footprints (mirror, dove [...] Read more.

Vortex beam encoded all-optical logic gates are suggested to be very important in future information processing. However, within current logic devices, only a few are encoded by using vortex beams and, in these devices, some space optical elements with big footprints (mirror, dove prism and pentaprism) are indispensable components, which is not conducive to device integration. In this paper, an integrated vortex beam encoded all-optical logic gate based on a nano-ring plasmonic antenna is proposed. In our scheme, by defining the two circular polarization states of the input vortex beams as the input logic states and the normalized intensity of the plasmonic field at the center of the nano-ring as the output logic states, OR and AND (NOR and NAND) logic gates are realized when two 1st (1st) order vortex beams are chosen as the two input signals; and a NOT logic gate is obtained when one 1st order vortex beam is chosen as the input signal. In addition, by defining the two linear polarization states (x and y polarization) of the input vortex beams as the two input logic states, an XNOR logic gate is realized when two 1st order vortex beams are chosen as the two input signals. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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10 pages, 3233 KiB

Open AccessArticle

High-Performance Transmission of Surface Plasmons in Graphene-Covered Nanowire Pairs with Substrate

by Da Teng, Kai Wang, Qiongsha Huan, Yongzhe Zhao and Yanan Tang

Nanomaterials 2019, 9(11), 1594; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9111594 - 10 Nov 2019

Cited by 12 | Viewed by 2261

Abstract

Graphene was recently proposed as a promising alternative to support surface plasmons with superior performances in the mid-infrared range. Here, we theoretically show that high-performance and low-loss transmission of graphene plasmons can be achieved by adding a silica substrate to the graphene-covered nanowire [...] Read more.

Graphene was recently proposed as a promising alternative to support surface plasmons with superior performances in the mid-infrared range. Here, we theoretically show that high-performance and low-loss transmission of graphene plasmons can be achieved by adding a silica substrate to the graphene-covered nanowire pairs. The effect of the substrate layer on mode properties has been intensively investigated by using the finite element method. Furthermore, the results show that inserting a low index material layer between the nanowire and substrate could compensate for the loss accompanied by the substrate, thus the mode properties could be adjusted to fulfill better performance. A reasonable propagation length of 15 μm and an ultra-small normalized mode area about ~10⁻⁴ could be obtained at 30 THz. The introduction of the substrate layer is crucial for practical fabrication, which provides additional freedom to tune the mode properties. The graphene-covered nanowire pairs with an extra substrate may inspire potential applications in tunable integrated nanophotonic devices. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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12 pages, 3676 KiB

Open AccessArticle

Densely Distributed Multiple Resonance Modes in a Fan-Shaped Plasmonic Nanostructure Demonstrated by FEM Simulations

by Qiong Wang, Zhengbiao Ouyang, Qiang Liu and Mi Lin

Nanomaterials 2019, 9(7), 975; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9070975 - 04 Jul 2019

Cited by 1 | Viewed by 2328

Abstract

Multiple resonance modes have important applications since they can provide multi-frequency operation for devices and bring great flexibility in practice. In this paper, based on a fan-shaped cavity coupled to a metal-isolator-metal (MIM) waveguide, a new kind of ultracompact plasmonic nanostructure is proposed [...] Read more.

Multiple resonance modes have important applications since they can provide multi-frequency operation for devices and bring great flexibility in practice. In this paper, based on a fan-shaped cavity coupled to a metal-isolator-metal (MIM) waveguide, a new kind of ultracompact plasmonic nanostructure is proposed to realize multiple resonance modes with dense distribution in a broad spectral range, and demonstrated through finite-element method (FEM) simulations. As many as ten resonance modes with an average interval of about 30 nm are obtained. They originate from the coexistence and interference of three types of basic modes in the fan-shaped cavity, i.e., the ring-waveguide modes, the modes in a ring array of periodic air grooves, and the metal-core-cavity modes. The dependence of resonance modes on structure parameters is investigated, which can provide an effective guide for choosing appropriate multiple-resonance-mode structures. Furthermore, by means of adjusting the geometrical asymmetry induced by the axial offset of the metal core in the fan-shaped cavity, the resonance modes can be effectively modulated, and some new modes appear because the wave path in the cavity is changed. The result proposes a novel way to create multiple resonance modes in plasmonic nanostructures, providing additional degrees of freedom for tailoring the resonance spectra and promising applications in various plasmonic devices, such as optical filters, ultrafast switches, biochemical sensors, and data storages. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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11 pages, 2139 KiB

Open AccessArticle

Linearly Tunable Fano Resonance Modes in a Plasmonic Nanostructure with a Waveguide Loaded with Two Rectangular Cavities Coupled by a Circular Cavity

by Qiong Wang, Zhengbiao Ouyang, Yiling Sun, Mi Lin and Qiang Liu

Nanomaterials 2019, 9(5), 678; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9050678 - 01 May 2019

Cited by 19 | Viewed by 2771

Abstract

Linear tunability has important applications since it can be realized by using linear control voltage and can be used conveniently without requiring nonlinear scale. In this paper, a kind of plasmonic nanostructure with a waveguide loaded with two rectangular cavities coupled by a [...] Read more.

Linear tunability has important applications since it can be realized by using linear control voltage and can be used conveniently without requiring nonlinear scale. In this paper, a kind of plasmonic nanostructure with a waveguide loaded with two rectangular cavities coupled by a circular cavity is proposed to produce four Fano resonance modes. The transfer matrix theory is employed to analyze the coupled-waveguide-cavity system. By analyzing the property of each single cavity, it reveals that the Fano resonances are originated from the coupling effect of the narrow modes in the metal-core circular cavity and the broad modes in the rectangular cavities. Owing to the interference of different modes, Fano peaks have different sensitivities on the cavity parameters, which can provide important guidance for designing Fano-resonance structures. Furthermore, adjusting the orientation angle of the metal core in the circular cavity can easily tune the line profile of Fano resonance modes in the structure. Especially, the figure of merit (FoM) increases linearly with the orientation angle and has a maximum of 8056. The proposed plasmonic system has the advantage of high transmission, ultracompact configuration, and easy integration, which can be applied in biochemical detecting or sensing, ultra-fast switching, slow-light technologies, and so on. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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10 pages, 2090 KiB

Open AccessArticle

Enhancement of Single-Photon Emission Rate from InGaAs/GaAs Quantum-Dot/Nanowire Heterostructure by Wire-Groove Nanocavity

by Wei Wei, Xin Yan, Jie Liu, Bing Shen, Wei Luo, Xiaofeng Ma and Xia Zhang

Nanomaterials 2019, 9(5), 671; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9050671 - 01 May 2019

Cited by 8 | Viewed by 3158

Abstract

Spontaneous emission of luminescent material is strongly dependent on the surrounding electromagnetic environment. To enhance the emission rate of a single-photon emitter, we proposed a wire-groove resonant nanocavity around the single-photon emitter. An InGaAs quantum dot embedded in a GaAs nanowire was employed [...] Read more.

Spontaneous emission of luminescent material is strongly dependent on the surrounding electromagnetic environment. To enhance the emission rate of a single-photon emitter, we proposed a wire-groove resonant nanocavity around the single-photon emitter. An InGaAs quantum dot embedded in a GaAs nanowire was employed as a site-control single-photon emitter. The nanoscale cavity built by a wire-groove perpendicular to the quantum dot with an extremely narrow width of 10 nm exhibited an extremely small volume of 10 × 40 × 259 nm³. Theoretical analysis showed that the emission rate of the quantum dot was dramatically enhanced by 617x due to the Purcell effect induced by the wire-groove cavity. A fast single-photon emitter with a rate of 50.2 GHz can be obtained that speeds up the data rate of the single-photon emitter. This ultrafast single-photon source would be of great significance in quantum information systems and networks. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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10 pages, 3074 KiB

Open AccessArticle

Compounding Plasmon–Exciton Strong Coupling System with Gold Nanofilm to Boost Rabi Splitting

by Tingting Song, Zhanxu Chen, Wenbo Zhang, Limin Lin, Yanjun Bao, Lin Wu and Zhang-Kai Zhou

Nanomaterials 2019, 9(4), 564; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9040564 - 07 Apr 2019

Cited by 13 | Viewed by 4043

Abstract

Various plasmonic nanocavities possessing an extremely small mode volume have been developed and applied successfully in the study of strong light-matter coupling. Driven by the desire of constructing quantum networks and other functional quantum devices, a growing trend of strong coupling research is [...] Read more.

Various plasmonic nanocavities possessing an extremely small mode volume have been developed and applied successfully in the study of strong light-matter coupling. Driven by the desire of constructing quantum networks and other functional quantum devices, a growing trend of strong coupling research is to explore the possibility of fabricating simple strong coupling nanosystems as the building blocks to construct complex systems or devices. Herein, we investigate such a nanocube-exciton building block (i.e. AuNC@J-agg), which is fabricated by coating Au nanocubes with excitonic J-aggregate molecules. The extinction spectra of AuNC@J-agg assembly, as well as the dark field scattering spectra of the individual nanocube-exciton, exhibit Rabi splitting of 100–140 meV, which signifies strong plasmon–exciton coupling. We further demonstrate the feasibility of constructing a more complex system of AuNC@J-agg on Au film, which achieves a much stronger coupling, with Rabi splitting of 377 meV. This work provides a practical pathway of building complex systems from building blocks, which are simple strong coupling systems, which lays the foundation for exploring further fundamental studies or inventing novel quantum devices. Full article

(This article belongs to the Special Issue Advances in Photonic and Plasmonic Nanomaterials)

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