scholarly journals Investigating the Fabrication Imperfections of Plasmonic Nanohole Arrays and Its Effect on the Optical Transmission Spectra

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Amr M. Mahros ◽  
Marwa M. Tharwat
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Optical Transmission ◽  
Fdtd Method ◽  
Extraordinary Optical Transmission ◽  
Gold Films ◽  
Transmission Spectra ◽  
Nanohole Arrays ◽  
Optical Transmission Spectra ◽  
Difference Time

We investigate the extraordinary optical transmission spectra of thin gold films perforated with imperfect nanohole arrays using the finite difference time domain (FDTD) method. Exponential shapes for the nanohole sidewalls are used. To the best of our knowledge, such investigation of transmission spectra of imperfect nanohole arrays has not previously been demonstrated. It was found that the asymmetry between the two openings of the circular nanoholes or bending to their sidewalls strongly modifies both the intensity and resonance positions of the transmission spectra. Furthermore, the results of this study assist in explaining the technicality of extraordinary optical transmission phenomenon and why some experimental results on transmission differ from those expected.

INVESTIGATION OF OPTICAL TRANSMISSION THROUGH A GOLD GRATING WITH SEMICIRCLE BUMPS USING FDTD METHOD

2013 ◽  
Vol 27 (17) ◽  
pp. 1350126 ◽  
Author(s):  
XIN ZHOU ◽  
JIANSHU FANG ◽  
QIANQUAN ZHU ◽  
BIN TANG ◽  
ZHIMIN LIU
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Optical Transmission ◽  
Fdtd Method ◽  
Resonance Field ◽  
Field Distributions ◽  
Fabry Perot ◽  
Electric And Magnetic Field ◽  
Difference Time ◽  
Phase Resonance

The optical transmissions through a gold grating with semicircle bumps were investigated using finite difference time domain (FDTD) method. As the semicircle bumps are set symmetrically in the slits, the resonant peaks for even modes exhibit a redshift, while odd modes exhibit a blueshift compared with the resonant peaks of the smooth slit grating. When the semicircle bumps are set asymmetrically, obvious resonant dips in the transmission spectrum appeared and they can be modulated by shifting the position of bumps in one slit and changing one slit width. Based on the electric and magnetic field distributions, Fabry–Pérot-like resonance, field interference and phase resonance mechanisms have been suggested for the physical origins of these observations.

Refractive index and temperature sensing based on defect resonator coupled with a MIM waveguide

2019 ◽  
Vol 33 (03) ◽  
pp. 1950017 ◽  
Author(s):  
Fang Chen ◽  
Jijun Li
Keyword(s):  
Refractive Index ◽  
Time Domain ◽  
Temperature Sensor ◽  
Finite Difference Time Domain ◽  
Fdtd Method ◽  
High Sensitivity ◽  
Transmission Spectra ◽  
Asymmetric Transmission ◽  
Difference Time ◽  
Mim Waveguide

In this paper, a refractive index and temperature sensor based on Fano resonance is realized. The proposed structure is composed of a MIM waveguide and a defect cavity which is filled with sealed ethanol. The Fano spectra and field distribution is numerically investigated by the two-dimensional finite-difference time-domain (FDTD) method. Due to the symmetry breaking, the sharp and asymmetric transmission spectra can be used as a sensor with high sensitivity. The sensitivity of the proposed structure can be up to 652 nm/RIU and [Formula: see text]. Because of the high sensitivity, the proposed plasmonic structure may have potential application in nanosensing.

scholarly journals From Time-Collocated to Leapfrog Fundamental Schemes for ADI and CDI FDTD Methods

Axioms ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 23
Author(s):  
Eng Leong Tan
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Method ◽  
Unconditionally Stable ◽  
Alternating Direction Implicit ◽  
One Dimensional ◽  
Alternating Direction ◽  
Fdtd Methods ◽  
Difference Time

The leapfrog schemes have been developed for unconditionally stable alternating-direction implicit (ADI) finite-difference time-domain (FDTD) method, and recently the complying-divergence implicit (CDI) FDTD method. In this paper, the formulations from time-collocated to leapfrog fundamental schemes are presented for ADI and CDI FDTD methods. For the ADI FDTD method, the time-collocated fundamental schemes are implemented using implicit E-E and E-H update procedures, which comprise simple and concise right-hand sides (RHS) in their update equations. From the fundamental implicit E-H scheme, the leapfrog ADI FDTD method is formulated in conventional form, whose RHS are simplified into the leapfrog fundamental scheme with reduced operations and improved efficiency. For the CDI FDTD method, the time-collocated fundamental scheme is presented based on locally one-dimensional (LOD) FDTD method with complying divergence. The formulations from time-collocated to leapfrog schemes are provided, which result in the leapfrog fundamental scheme for CDI FDTD method. Based on their fundamental forms, further insights are given into the relations of leapfrog fundamental schemes for ADI and CDI FDTD methods. The time-collocated fundamental schemes require considerably fewer operations than all conventional ADI, LOD and leapfrog ADI FDTD methods, while the leapfrog fundamental schemes for ADI and CDI FDTD methods constitute the most efficient implicit FDTD schemes to date.

scholarly journals Butterfly-Inspired 2D Periodic Tapered-Staggered Subwavelength Gratings Designed Based on Finite Difference Time Domain Method

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Houxiao Wang ◽  
Wei Zhou ◽  
Er Ping Li ◽  
Rakesh Ganpat Mote
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Fdtd Method ◽  
Subwavelength Structures ◽  
Surface Reflection ◽  
Subwavelength Gratings ◽  
Difference Time

The butterfly-inspired 2D periodic tapered-staggered subwavelength gratings were developed mainly using finite difference time domain (FDTD) method, assisted by using focused ion beam (FIB) nanoscale machining or fabrication. The periodic subwavelength structures along the ridges of the designed gratings may change the electric field intensity distribution and weaken the surface reflection. The performance of the designed SiO2gratings is similar to that of the corresponding Si gratings (the predicted reflectance can be less than around 5% for the bandwidth ranging from 0.15 μm to 1 μm). Further, the antireflection performance of the designedx-unspaced gratings is better than that of the correspondingx-spaced gratings. Based on the FDTD designs and simulated results, the butterfly-inspired grating structure was fabricated on the silicon wafer using FIB milling, reporting the possibility to fabricate these FDTD-designed subwavelength grating structures.

Application of ADE-FDTD Method in Lossy Lorentz Media

2014 ◽  
Vol 945-949 ◽  
pp. 2486-2489
Author(s):  
Qing Chao Nie ◽  
Bing Kang Chen
Keyword(s):  
Differential Equation ◽  
Wave Propagation ◽  
Finite Difference ◽  
Theoretical Result ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Method ◽  
Time Domain Method ◽  
Domain Method ◽  
Difference Time

A finite-difference time-domain method based on the auxiliary differential equation (ADE) technique is used to obtain the formulation of 2-D TM wave propagation in lossy Lorentz media. In the paper, the reflected coefficients calculated by ADE-FDTD method and the exact theoretical result are better agreement.

scholarly journals Size Determination of Polystyrene Sub-Microspheres Using Transmission Spectroscopy

2020 ◽  
Vol 10 (15) ◽  
pp. 5232
Author(s):  
Tien Van Nguyen ◽  
Linh The Pham ◽  
Khuyen Xuan Bui ◽  
Lien Ha Thi Nghiem ◽  
Nghia Trong Nguyen ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Fdtd Simulation ◽  
Transmission Spectra ◽  
Experimental Transmission ◽  
Straightforward Method ◽  
Quartz Substrates ◽  
Difference Time ◽  
Good Agreement

Nano/micro polystyrene (PS) beads have found many applications in different fields spanning from drug delivery, bio-diagnostics, and hybrid plasmonics to advanced photonics. The sizes of the PS beads are an important parameter, especially in plasmonic and photonic experiments. In this work, we demonstrate a quick and straightforward method to estimate the diameters of sub-microspheres (0.2 μm to 0.8 μm) using the transmission spectra of a close-packed monolayer of polystyrene beads on glass or quartz substrates. Experimental transmission spectra of the PS monolayers were verified against finite-difference time-domain (FDTD) simulation and showed good agreement. The effects of the substrates on the transmission spectra and, hence, the accuracy of the method were also studied by simulation, which showed that common transparent substrates only cause minor deviation of the PS bead sizes calculated by the proposed method.

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