Showing 144 results for Surface Plasmon
Dr. Vahid Fallahi, Mr. Ali Khaledi-Nasab,
year 20, Issue 0 (1-2014)
Abstract
The finite difference time domain method (FDTD) has been used to model the extinction cross section of silver (Ag) ellipsoidal nanoparticles. The localized surface Plasmon resonance frequencies strongly depend on the size and orientation of the nanoparticles. It has been calculated the longitudinal, transverse and hybrid modes for nanoparticles with prolate spheroid geometry. The longitudinal resonance mode occurs when the electric field of incident light is along the c-axis of the prolate spheroid. Similarly, the transverse resonance mode occurs when the electric field of incident light is perpendicular to the c-axis. In our calculations, the dielectric function has been obtained according to the Drude-Sommerfeld theory.
Mr Elyar Pourali, Prof. Mohammad Kazem Moravvej Farshi, Dr Majid Ebnali Heidari, Miss Zahra Mostashari Rad,
year 20, Issue 0 (1-2014)
Abstract
In this paper, using surface plasmon resonance effect, we demonstrate an optical OR gate. We have used gold and silver because of low losses of silver and gold in visible regime compared to other metals. The photonic crystal structure consists of a hexagonal lattice of iron nano rods, with a radius of r=50 nm and lattice constant of ɑ=200 nm, in a background of air. The designed optical gate, works in the wavelength of λ=0.65 μm with the TM (Hz,Ex,Ey) polarization. Simulation of this structure is done using the COMSOL software package.
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year 20, Issue 0 (1-2014)
Abstract
We report an experimental research on the magneto-optical enhanced in cobalt thin film by the aid of Ag/Au core shell nanoparticles. This magneto-plasmonic structure was prepared by laser ablation in liquids and electron beam deposition method. Our results show that we have sufficient enhancement in amplitude of electric field and we have enough magneto-optical Kerr rotation due to the light localization in the nanoparticles in wide wavelength range.
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year 20, Issue 0 (1-2014)
Abstract
In this study we attempt to obtain the angular response of surface plasmons in Metal-Dielectric interface. By use of a prism (BK7) as dielectric and Gold thin film as a metal, an abrupt dip is observed in reflectance-incident angle diagram that the corresponding angle of dip in reflectance is “resonance angle”. Our theoretical investigation has been carried out on the dependence of resonance angle on the thicknesses of Gold thin films based on Characteristic Transmission Matrix method. Contrary in experimental configuration, we use a He-Ne polarized laser as light source. Our results show the good agreement between theoretical and experimental result.
Mr Fakhroddin Kherad, Mr Mahmood Hosseini Farzad, Mr Abas Zarifi,
year 20, Issue 0 (1-2014)
Abstract
In this paper we show by three dimensional simulation the beam propagation in dielectric loaded surface plasmon-polariton waveguides (DLSPPWs) is more suitable comparison with the dielectric waveguides (the substrate is also dielectric). The best dimentions for these dielectric ridge is 600 nm for its with and thickness in 1.55 nm wave length. In two waveguides structures the coupling between them is occurred at the characteristic length. In this length the energy flux is transferred from one waveguide to other waveguide and vice versa. The speed of this transfering is increased when the distance between two waveguide is decreased.
Ms Somayeh Kashani, Mr Arashmid Nahal, Mr Yaser Abdi,
year 20, Issue 0 (1-2014)
Abstract
In this report formation of spontaneous periodic structures (SPS) in silver-nanoparticles-doped AgCl thin films and measurement of their absorption spectra is represented. We also simulate the absorption spectra of produced SPS based on Mie theory. Interference of the excited mode in AgCl thin film and the incident light beam results in the formation of spontaneous periodic structures. We have shown that SPS are sensitive to the polarization of incident light because of different absorption in different vertical directions. Inconformity of experimental data with simulation were discussed in terms of NPs shape, size and dielectric surrounding medium.
Behrooz Eftekharinia, Dr. Ahmad Moshaii, Hasan Nabavi,
year 20, Issue 0 (1-2014)
Abstract
We propose a new design for metallic slit-groove nanostructure to increase the propagation intensity of a unidirectional surface plasmon polariton (SPP) light beam. Our idea is based on the combination of the concept of unidirectional plasmonic wave propagation in a metallic slit-groove nanostructure with the well-known hybrid modes of a hybrid metal-dielectric waveguide. We show that this novel structure results in up to 5 times enhancement in the SPP beam intensity relative to the conventional design of slit-groove nanostructure.
Mr Majed Akbari, Dr. Abolfazl Chamanmotlagh,
year 20, Issue 0 (1-2014)
Abstract
In this paper, a numerical method has been utilized in order to analyze of Low-Loss Hybrid Silicon Plasmonics Waveguides and Metal Plasmonics waveguides. Using silicon instead of noble metals (e.g. Au and Ag) is an advantage in designing of photonic waveguides due to have low-loss in comparison to noble at telecom bandwidth. The presented results show that the new model has smaller structures and have better performance in the terms mode confinement and propagation loss.
Salma Mousavi, Parnian Khavanin, Dr. Fardin Kheirandish,
year 20, Issue 0 (1-2014)
Abstract
In this paper the scattering of surface waves in the presence of a single defect in the metal-vacuum interface is investigated. By modifying the previous methods we could explore more general forms of defect and get transmission, reflection and scattering coefficients of surface plasmon using both Rayleigh expansions and the exact numerical solution of integral equation. Providing a new defect, reflection coefficient of the structure greatly increased compared to conventional structures. The maximum reflectivity is achieved when the defect is narrow which is called plasmon mirror.
Dr. Najmeh Nozhat, Dr. Nosrat Granpayeh,
year 20, Issue 0 (1-2014)
Abstract
In this paper, all-optical switches based on plasmonic square ring resonator (PSRR) with smooth corner bends have been proposed. Both three and four ports nonlinear switches have been numerically analyzed and simulated by the finite-difference time-domain (FDTD) method. By applying Kerr nonlinear self-phase modulation (SPM) effect, it has been shown that in four port switches the output power ratio of 12.77dB can be achieved by the switching power of 11.84 (kW/m), whereas the switching power of 12 (kW/m) is needed for attaining the power ratio of 16.8dB in three port switches. PSRRs are suitable for using in photonic integrated circuits as all-optical switches because of their nanoscale size and low required switching power.
Parnian Khavanin, Salma Mousavi, Dr. Fardin Kheirandish, Hamidreza Mohammadi Khoshoei,
year 20, Issue 0 (1-2014)
Abstract
The decay rate of an excited atom in the dipole approximation is described by using Fermi's golden rule which is related to the imaginary part of the vector potential Green's function by applying the fluctuation dissipation theorem and Kubo's formula. In this paper, we examined the radiative properties of an excited atom in front of a real metal and it can be seen that the decay rate of an excited atom in the presence of surface plasmons increases as the distance between atom and the surface vanishes.
Dr. Mehrdad Moradi, Mr. Davood Rezvani, Mr. Saman Mahmoodi,
year 20, Issue 0 (1-2014)
Abstract
Magneto-plasmonic crystals formed by a plasmonic layer near a magnetic layer. In this paper, the optimal thicknesses of magneto-plasmonic crystal Au/Ni for enhancement of magneto-optical Kerr effect (MOKE) have been investigated theoretically. In Glass/Au/Ni structure gold and nickel used as plasmonic and magnetic materials respectively. The maximum Kerr signal 16.46 degree was obtained by 9 nm thick film of gold and 10 nm thick of nickel layer in Glass/Au/Ni structure at 47 degree of incident angle. Also, the maximum Kerr signal 24.17 degree was obtained by 7 nm thickness of Gold layer and 13 nm thickness of Nickel layer in Glass/Ni/Au structure at 48 degree of incident angle.
Nahid Farkhari, Ahmad Moshaii, Maryam Nikkhah, Sara Abbasian,
year 20, Issue 0 (1-2014)
Abstract
In this paper, we have investigated the adsorption properties of different strands of a DNA to the colloidal nanoparticles. We measured the plasmonic spectrums of the nanoparticles under the presence of different oligonucleotids. It is shown that the quality of the adsorption of different strands of DNAs on the nanoparticles strongly depends on the sequence of the DNAs. Between the different bases of a DNA, the base (A) has the best and the base (G) has the worst attachment to the nanoparticles. It is also shown that with increment of the DNA concentration, the adsorption of the silver nanoparticles to the DNAs increases leading to a more protection of the nanoparticles against salt-induced aggregation.
Dr. Mehrdad Moradi, Mr. Davood Rezvani, Mr. Saman Mahmoodi,
year 20, Issue 0 (1-2014)
Abstract
By adding a plasmonic metal in magneto-optical crystals one can examine both plasmonic and magneto-optical (MO) phenomena simultaneously. Therefore we want to design an optimal structure for amplifying the Magneto-optical Kerr Effect (MOKE) using calculation based on 4×4 transfer matrix method. In Glass/Au/Co structure a thin gold layer used as plasmonic metal and a cobalt layer as magnetic material. The maximum Kerr signal 59.83 degree was obtained by 11 nm thickness of gold layer and 6 nm thickness of cobalt layer in Glass/Au/Co structure in 599 nm wavelength at 49 degree of incident angle.
Dr. Mahmood Hosseini Farzad, Mr. Mohammad Ali Managheb, Ms. Mozhdeh Janfada,
year 21, Issue 0 (3-2015)
Abstract
Abstract- In this paper, by using of 3D finite difference time domain (FDTD) method, we investigate and simulate the transmission of a white light through a 2D dimensional lattice of the crossed metal nano-antennas. This array of nano-antennas operate like a dynamical color filter based on the localized surface plasmon resonance which is generate different colors according to the changing the linear polarization angle of the incident white light. In this paper, the effect of different parameters such as period of the array and material of the nano-antenna on the performance of the filter and also electric field distributions on the nano-antenna at wavelength of the minimum transmission, in order to justify the role of the LSPs in this structure are investigated.
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year 21, Issue 0 (3-2015)
Abstract
In this paper we investigate the transmission spectra of polycarbonate/Au plasmonic grating and the possibility of tuning surface Plasmon polariton absorption in this structure by use of changing polar and azimuthal angles of grating with respect to the incident beam. Increasing in the polar angle of sample yield to shifted absorbed wavelengths to the smaller wavelengths. Also, with the increase of azimuthal angle, the absorbed wavelengths will shift to the larger wavelengths which are very suitable in sensor applications.
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year 21, Issue 0 (3-2015)
Abstract
scientists try to introduce and develop new structures based on the plasmonics. In this paper we try to design and fabricate a new plasmonic polarizer based on metal nano-grating consist of silver thin film on polycarbonante gratings. Our results show the 28 % polarized light in overall visible light. This new devices can open a new insight in plasmonic based polarizers.
Mohammad Kouhi, Mahsa Moharrami,
year 21, Issue 0 (3-2015)
Abstract
In this paper the capability of metals nanolayer used in surface plasmon resonance (SPR) based fiber optic sensing is investigated theoretically. The sensitivity of the SPR based fiber optic sensor with two different metals (gold and silver) and various thickness of the metal film is obtained numerically. The calculation results are shown that with increasing of thickness of the metal film the sensitivity of fiber optic sensor is increased too. Furthermore, it is found that in the SPR based fiber optic sensor with same thickness of two metals, Au metal film has further sensitivity than Ag.
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year 21, Issue 0 (3-2015)
Abstract
Here we report the optical absorptance of metallic grating coupled to the one-dimensional photonic crystal layers to investigate the multiple surface Plasmon polariton waves and waveguide modes. Our dielectric photonic crystal was made by electron gun deposition method onto the Aluminium thin film on the polycarbonate grating. These surface Plasmon polariton waves at the interface of metallic grating are very sensitive to the polar incidence angles which can be used to the light trapping for solar cell applications.
Mr. Saeed Dabiri, Dr. Mehdi Sovizi,
year 21, Issue 0 (3-2015)
Abstract
- In this paper the effect of temperature on the performance of Photonic crystal waveguide sensor based on surface plasmon resonance is theoretically investigated. To analyze the propagation of light in the waveguide the Mtarix method is used and then the temperature effect on the sensor is analized. It is observed that the defects mode varies in peak height, which could be used as a mechanism for temperature sensing applications.
