scholarly journals Novel nano-plasmonic sensing platform based on vertical conductive bridge

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hyo-Seung Park ◽  
Jongkil Park ◽  
Joon Young Kwak ◽  
Gyu-Weon Hwang ◽  
Doo-Seok Jeong ◽  
...  
Keyword(s):  
Electric Field ◽  
Incident Light ◽  
Geometrical Parameters ◽  
Theoretical Simulation ◽  
Resonance Modes ◽  
High Tunability ◽  
Fluid Analysis ◽  
Plasmonic Sensing ◽  
Sensing Platform ◽  
Conductive Bridge

AbstractA novel nano-plasmonic sensing platform based on vertical conductive bridge was suggested as an alternative geometry for taking full advantages of unique properties of conductive junction while substantially alleviating burdens in lithographic process. The effects of various geometrical parameters on the plasmonic properties were systematically investigated. Theoretical simulation on this structure demonstrates that the presence of vertical conductive bridge with smaller diameter sandwiched between two adjacent thin nanodiscs excites a bridged mode very similar to the charge transfer plasmon and exhibits a remarkable enhancement in the extinction efficiency and the sensitivity when the electric field of incident light is parallel to the conductive bridge. Furthermore, for the electric field perpendicular to the bridge, another interesting feature is observed that two magnetic resonance modes are excited symmetrically through open-gaps on both sides of the bridge together with strongly enhanced electric field intensity, which provides a very favorable environment as a surface enhanced Raman scattering substrate for fluid analysis. These results verify a great potential and versatility of our approach for use as a nanoplasmonic sensing platform. In addition, we demonstrated the feasibility of fabrication process of vertical conductive bridge and high tunability in controlling the bridge width.

scholarly journals Optimization Based on the Surface Plasmon Optical Properties of Adjustable Metal Nano-Microcavity System for Biosensing

2021 ◽  
Vol 9 ◽  
Author(s):  
Jin Zhu ◽  
Yiye Yang ◽  
Yanping Yin ◽  
Huining Yuan
Keyword(s):  
Optical Properties ◽  
Electric Field ◽  
Gold Film ◽  
Incident Light ◽  
Extinction Spectrum ◽  
High Sensitivity ◽  
Element Analysis ◽  
Environmental Media ◽  
Resonance Modes ◽  
High Concentrations

This paper mainly studies the plasma optical properties of the silver nanorod and gold film system with gap structure. During the experiment, the finite element analysis method and COMSOL Multiphysics are used for modeling and simulation. The study changes the thickness of the PE spacer layer between the silver nanorod and the gold film, the conditions of the incident light and the surrounding environment medium. Due to the anisotropic characteristics of silver nanorod, the microcavity system is extremely sensitive to the changes of internal and external conditions, and the system exhibits strong performance along the long axis of the nanorod. By analyzing the extinction spectrum of the nanoparticle and the electric field section diagrams at resonance peak, it is found that the plasma optical properties of the system greatly depend on the gap distance, and the surrounding electric field of the silver nanorod is confined in the gap. Both ends of the nanorod and the gap are distributed with high concentrations of hot spots, which reflects the strong hybridization of multiple resonance modes. Under certain excitation conditions, the plasma hybridization behavior will produce a multi-pole mode, and the surface electric field distribution of the nanorod reflects the spatial directionality. In addition, the system is also highly sensitive to the environmental media, which will cause significant changes in its optical properties. The plasma microcavity system with silver nanorod and gold film studied in this paper can be used to develop high-sensitivity biosensors, which has great value in the field of biomedical detection.

scholarly journals Design of a Liquid-Crystal-Tunable Terahertz Demultiplexer Based on a Metal-Insulator-Metal Waveguide

2019 ◽  
Vol 9 (4) ◽  
pp. 644
Author(s):  
Xue-Shi Li ◽  
Naixing Feng ◽  
Yuan-Mei Xu ◽  
Liang-Lun Cheng ◽  
Qing Liu
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Metal Insulator ◽  
Resonance Modes ◽  
External Bias ◽  
Bias Electric Field ◽  
Metal Waveguide ◽  
Metal Insulator Metal ◽  
Fabry Perot ◽  
Mim Waveguide

A tunable demultiplexer with three output channels infiltrated by liquid crystal (LC) is presented, which is based on a metal-insulator-metal (MIM) waveguide. The operating frequencies of the three output channels can be tuned simultaneously at will by changing the external bias electric field applied to the LC. By analyzing the Fabry-Pérot (FP) resonance modes of the finite-length MIM waveguide both theoretically and numerically, the locations of the three channels are delicately determined to achieve the best demultiplexing effects. Terahertz (THz) signals input from the main channel can be demultiplexed by channels 1, 2 and 3 at 0.7135 THz, 1.068 THz and 1.429 THz, respectively. By applying an external electric field to alter the tilt angle of the infiltrating LC material, the operating frequencies of channels 1, 2 and 3 can be relatively shifted up to 12.3%, 9.6% and 9.7%, respectively. The designed demultiplexer can not only provide a flexible means to demultiplex signals but also tune operating bands of output channels at the same time.

scholarly journals Plasmonic Sensing Studies of a Gas-Phase Cystic Fibrosis Marker in Moisture Laden Air

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3776
Author(s):  
Libin Sun ◽  
Douglas Conrad ◽  
Drew A. Hall ◽  
Kurt D. Benkstein ◽  
Steve Semancik ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Detection Limit ◽  
Gas Phase ◽  
Localized Surface Plasmon ◽  
Exhaled Breath ◽  
Nanohole Array ◽  
Dry Air ◽  
Plasmonic Sensing ◽  
Sensing Platform ◽  
The Status

A plasmonic sensing platform was developed as a noninvasive method to monitor gas-phase biomarkers related to cystic fibrosis (CF). The nanohole array (NHA) sensing platform is based on localized surface plasmon resonance (LSPR) and offers a rapid data acquisition capability. Among the numerous gas-phase biomarkers that can be used to assess the lung health of CF patients, acetaldehyde was selected for this investigation. Previous research with diverse types of sensing platforms, with materials ranging from metal oxides to 2-D materials, detected gas-phase acetaldehyde with the lowest detection limit at the µmol/mol (parts-per-million (ppm)) level. In contrast, this work presents a plasmonic sensing platform that can approach the nmol/mol (parts-per-billion (ppb)) level, which covers the required concentration range needed to monitor the status of lung infection and find pulmonary exacerbations. During the experimental measurements made by a spectrometer and by a smartphone, the sensing examination was initially performed in a dry air background and then with high relative humidity (RH) as an interferent, which is relevant to exhaled breath. At a room temperature of 23.1 °C, the lowest detection limit for the investigated plasmonic sensing platform under dry air and 72% RH conditions are 250 nmol/mol (ppb) and 1000 nmol/mol (ppb), respectively.

scholarly journals Electrically-Tunable Blue Phase Liquid Crystal Microlens Array Based on a Photoconductive Film

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 65 ◽  
Author(s):  
Bing-Yau Huang ◽  
Shuan-Yu Huang ◽  
Chia-Hsien Chuang ◽  
Chie-Tong Kuo
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Electric Field ◽  
Uv Light ◽  
Focal Length ◽  
Incident Light ◽  
Microlens Array ◽  
Gradient Distribution ◽  
Phase Liquid ◽  
Blue Phase

This paper proposes an effective approach to fabricate a blue phase liquid crystal (BPLC) microlens array based on a photoconductive film. Owing to the characteristics of photo-induced conducting polymer polyvinylcarbazole (PVK), in which conductivity depends on the irradiation of UV light, a progressive mask resulting in the variation of conductivity is adopted to produce the gradient distribution of the electric field. The reorientations of liquid crystals according to the gradient distribution of the electric field induce the variation of the refractive index. Thus, the incident light experiences the gradient distribution of the refractive index and results in the focusing phenomenon. The study investigates the dependence of lens performance on UV exposure time, the focal length of the lens, and focusing intensities with various incident polarizations. The BPLC microlens array exhibits advantages such as electrically tunability, polarization independence, and fast response time.

Electro-Optical Simulation Of In Ultra-Thin Photonic Crystal Amorphous Silicon Solar Cells

2019 ◽  
Vol 5 (2) ◽  
pp. 10-21
Author(s):  
Abdelhak Merabti ◽  
Abdelkader Bensliman ◽  
Mahmoud Habab
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Photonic Crystal ◽  
Electric Field ◽  
Active Layer ◽  
Conversion Efficiency ◽  
Cell Structure ◽  
Photovoltaic Performance ◽  
Optical Simulation ◽  
Geometrical Parameters

Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. The critical problem in the a-Si:H-based photovoltaic cell is increasing the conversion efficiency. To overcome the difficulty,  higher conversion efficiency demands a longer optical path  to increase optical absorption. Thus, a light trapping  structure is needed to obtain more efficient absorption. In this context, we propose a complete solar cell structure for which a 1D grating is etched into the ultrathin active absorbing layer of a one-dimensional "CP 1D" photonic crystal a-Si: H characterized by the optimal parameters: period a = 480 nm, a filling factor ff = 50% and a depth d = 150 nm. This was selected by varying the CP1D parameters to maximize the absorption integrated into the active layer. CP1D is suggested as an intermediate layer in the solar cell concentration system. This study allowed us to model the optical and electrical behavior of a CP1D solar cell. After optimization of the geometrical parameters (period and fill factor ... etc.), we concluded that the CP1D led to greater optical gains than for their unstructured equivalent. The simulation clearly illustrates that the electric field strongly affects the electro-optical characteristics of the devices studied, and that it is clear that 1D PC solar cells as active layer have exhibited a high electric field distribution. We have focused on the net on the effect of the active layer and its beneficial role in the sense of expressing the photovoltaic performance of the devices.

scholarly journals Surface Plasmons for Probing Optical Data of Multi- Layered Thin Films

2000 ◽  
Vol 5 ◽  
pp. 105
Author(s):  
A. Rais ◽  
A. Sellai
Keyword(s):  
Surface Plasmons ◽  
Optical Constant ◽  
Incident Light ◽  
Air Gap ◽  
Optical Data ◽  
Layered System ◽  
Geometrical Parameters ◽  
Matrix Formalism ◽  
Minimization Method ◽  
Al Oxide

In this paper, we show how optical excitation of surface plasmons (SPs) can be used to obtain optical and geometrical parameters of specific layers in multi-layered thin film systems. The optimum coupling phenomenon between incoming p-polarized light and SPs appears as a minimum in the reflectance that is calculated using a standard matrix formalism. The sensitive dependence of the reflectance minimum on optical and geometrical parameters suggests that they can be determined accurately by fitting the measured attenuated total reflectance (ATR) to the matrix-calculated reflectance using the Simplex minimization method. The procedure is applied to the multi-layered system: Prism / Air gap / Al-oxide / Al / GaAs. At fixed incident light wavelength, the fitting parameters are the Al-oxide optical constant and the thickness of the air gap, Al-oxide and Al layers. Fortran codes are implemented for the reflectance calculations and the fitting procedures. The results show that the theoretical reflectance fits well the measured ATR at 633 nm wavelength. Moreover, the modeled Al-oxide optical constant at this wavelength agrees well with the literature. However, the reflectance fits are less good at 590 nm and 458 nm wavelengths and their modeled Al-oxide optical constants show a dispersion effect in disagreement with the literature. The modeled geometrical parameters are consistent with the nominal values.

scholarly journals Nonlinear plasmonic metasurfaces assisted laser mode locking

2020 ◽  
Vol 243 ◽  
pp. 14001
Author(s):  
Lei Zhang ◽  
Jiyong Wang ◽  
Aurelien Coillet ◽  
Philippe Grelu ◽  
Benoit Cluzel ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Incident Light ◽  
Mode Locking ◽  
Pulse Generation ◽  
Nonlinear Regime ◽  
Practical Implementation ◽  
Saturable Absorption ◽  
Geometrical Parameters ◽  
Neuromorphic Circuits ◽  
Saturable Absorbers

Plasmonic metasurfaces are artificial 2D layers made of subwavelength elementary cells, which give rise to novel wave properties that do not exist in nature. In the linear regime, their applications have been extensively studied, especially in wavefront manipulation for lensing, holography or polarization control. Interests in metasurfaces operating in nonlinear regime have also increased due to their ability to efficiently convert the fundamental light into harmonic frequencies and multiphoton emissions. Nevertheless, practical applications in the nonlinear regime have been rarely reported. In this study, we report that plasmonic metasurfaces with well-controlled polarimetric nonlinear transfer functions perform as saturable absorbers with modulation performances superior to that of other 2D materials. We employ planar nanotechnologies to fabricate 2D plasmonic metasurfaces with precise size, gap and orientation. We quantify the relationship between saturable absorption and the plasmonic resonances of the unit cell by altering the excitation power of pumping laser, the polarization of incident light and the geometrical parameters of the plasmonic metasurfaces. Finally, we provide a practical implementation by integrating the saturable metasurfaces into a fiber laser cavity and realize a stable self-starting ultrashort laser pulse generation. As such, this work sheds light on ultrathin nonlinear saturable absorbers for applications where nonlinear functions are required, such as in ultrafast laser or neuromorphic circuits.

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