Showing 5 results for Fdtd
Mr Hossein Vejdani Shoja, Dr Ali Arab, Mrs Minoo Shojaei Far,
Volume 9, Issue 1 (1-2015)
Abstract
In this paper, an ideal cylindrical metamaterial invisibility cloak with infinite-length which its electric permittivity and magnetic permeability mapped to the Drude dispersion model is simulated. The sinusoidal plane waves with microwave frequencies used as sources. To this end, the dispersive finite-difference time-domain method (FDTD) used with Convolutional Perfectly Matched Layered (CPML) absorbing boundaries conditions. A comparison performed between scattering of cloaked and non-cloaked PEC cylinder. And finally, the influence of incident wave frequency, thickness of cloak and observer angle relative to the propagation line to performance of cloak, was surveyed.
Mohammad Danaie, Ruhollah Nasiri Far, Abbas Dideban,
Volume 12, Issue 1 (1-2018)
Abstract
In this paper, a Y-shaped power splitter based on a two dimensional photonic crystal (PhC) for TE modes is designed and optimized. A triangular lattice of air holes is used for Y-shaped power divider. For analyzing these structures, plane wave expansion (PWE) and finite difference time domain (FDTD) methods are used. The simulation results show that more than 98% of the input power is transmitted to the outputs and the structure has just less than 2% reflected power. According to the simulation results this structure is suitable for high bandwidth optical integrated circuit at the 1550 nm wavelength.
Samaneh Biabani, Gholamreza Foroutan,
Volume 13, Issue 2 (12-2019)
Abstract
The dynamics of fast gas heating in a high power microwave discharge in air, is investigated in the framework of FDTD simulations of the Maxwell equations coupled with the fluid simulations of the plasma. It is shown that, an ultra-fast gas heating of the order of several 100 Kelvins occurs in less than 100 ns. The main role in the heating is played by the electron impact dissociation of , dissociation via quenching of metastable states of , as well as, quenching by nitrogen molecules. Among the electronically excited metastable states, are the most important species. Slow heating of the gas above 1 is attributed to the vibrational relaxation processes of , among them vibrational-translational relaxation of demonstrates the highest heating rate. The heating rate and thus the gas temperature are significantly increased with increasing of the microwave pulse amplitude, pulse width, and the gas pressure. In all cases, enhanced dissociation is the main factor behind the enhanced gas heating. The same effects are observed for increasing of the initial gas temperature, and percentage in a mixture.
Leila Sheikhi, Abbas Azarian,
Volume 14, Issue 2 (12-2020)
Abstract
In hollow nanostructures, the inner and outer surface plasmons couple together that provides interesting plasmonic properties resulting in the enhancement of the plasmonic field. In addition, triangular structures are interesting for plasmonic applications due to their sharp corners and low symmetry. In this work, gold triangular nanostructures with triangular (TTN) and circular (CTN) holes in their centers have been simulated using the FDTD method and their plasmonic properties have been compared. The extinction spectra of the structures display that CTN has only one plasmonic peak, whereas TTN has several plasmonic modes due to its lower symmetry. Each peak presents different interactions between the multipoles that understand from the charge density distribution. Also, the figure of merit (FOM) of the peaks has been calculated and a high value of 33 is obtained for one of the TTN modes, which is appropriate for sensing application.
Akram Kabiri, Abbas Azarian,
Volume 15, Issue 1 (1-2021)
Abstract
Plasmonic nanosensors have emerged as a powerful tool for biosensing and other applications. Therefore, efforts are underway to achieve higher sensitivity for these nanosensors. In line with this goal, we have investigated the sensitivity of silver square and triangular chiral nanosensors based on two strategies, Localized Surface Plasmon Resonance (LSPR)-based and Circular Dichroism (CD)-based sensing. Chiral nanostructure parameters (height, diameter) and the angle of incidence light have been optimized with calculation method (3-D finite-difference time-domain (3-D- FDTD)) in order to obtain best localized surface plasmon resonance and consequently the highest sensitivity. The calculation results show that sensitivitys~1727 and 1658nmRIU-1 can be achieved in LSPR- and CD-based sensing method respectively for square chiral nanostructure, which are significantly more than previous works.
