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diffracted-orders
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Enhanced optical transmission through metallic holes array: role of te polarization in spp excitation
, Article Plasmonics ; Volume 8, Issue 2 , June , 2013 , Pages 403-409 ; 15571955 (ISSN) ; Rashidian, B ; Sharif University of Technology
2013
Abstract
Optical transmission through double-layer metallic subwavelength holes array is studied under oblique incidence by split-field finite-difference time-domain method. Both TM and TE polarizations are investigated. It is proved that the transmission peaks can also be observed for TE polarization due to the excitation of surface plasmon polaritons (SPP) through diffraction orders. By changing the incident angle, these transmission peaks follow the SPP wavelength shift. The field profiles, even for the field components not present in the incident field, clearly show the SPP excitation. The mechanism of enhanced transmission will be fully discussed
Modeling of periodic array of cut-through slits with sinusoidal surface conductivity at the interfaces of an anisotropic medium
, Article IEEE Transactions on Antennas and Propagation ; Volume 66, Issue 10 , 2018 , Pages 5630-5633 ; 0018926X (ISSN) ; Mehrany, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
A periodic arrangement of 1-D slits carved in a perfect electric conductor is investigated, and an equivalent model which features sinusoidal surface conductivity on its upper and lower interfaces is derived. Therefore, and in sheer contrast to all the previous attempts that were successful in mimicking only the zeroth-order diffracted waves, it is capable of emulating both specular and nonspecular diffraction orders. The accuracy of the model is verified by the full-wave simulations. The proposed model is used to study the sharp Fano-type extraordinary transmission resonances arising in the structure. The transmission spectrum near these resonances is derived in terms of Fano resonance...
Analysis and Design of Optical Devices by Colloidal Nano-Structures
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
The colloidal crystals are formed of spherical particles and can be fabricated using simple and low-cost chemical methods. Optical properties of colloidal crystals should be recognized properly in order to design optical devices based on these nano-structures. Reflection and transmission coefficients of these multilayer structures are very important for understanding their properties. Semi-analytical methods like Fourier Modal method (FMM) can be very useful to obtain their reflection and transmission properties of these multilayer structures. In this thesis, we try to implement Matched Coordinate (MC) and Adaptive Spatial Resolution (ASR) techniques in the FMM. These techniques increase...
Planar resonant blazed gratings from a circuit model standpoint
, Article IEEE Transactions on Antennas and Propagation ; Volume 68, Issue 4 , 4 April , 2020 , Pages 2765-2778 ; Rodriguez Berral, R ; Mesa, F ; Medina, F ; Memarian, M ; Itoh, T ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
The equivalent circuit approach (ECA) is used in this work to analyze and design a previously proposed one-dimensional planar blazed grating of the resonant type. The analysis covers both the classical Littrow configuration, when the direction of the relevant diffracted order coincides with that of the incident wave (Bragg blazing), and when these directions are different (off-Bragg blazing). Once the scattering problem of the grating structure is posed as a discontinuity problem inside an equivalent generalized waveguide (corresponding to the unit cell of the original structure) and studied in terms of its equivalent circuit network, the possibility of transferring all the power of the...
Perfect anomalous reflection using a compound metallic metagrating
, Article Optics Express ; Volume 28, Issue 11 , 2020 , Pages 16439-16452 ; Khavasi, A ; Sharif University of Technology
OSA - The Optical Society
2020
Abstract
Metagrating is a new concept for wavefront manipulation that, unlike phase gradient metasurfaces, does not suffer from low efficiency and also has a less complicated fabrication process. In this paper, a compound metallic grating (a periodic metallic structure with more than one slit in each period) is proposed for anomalous reflection. We propose an analytical method for analyzing the electromagnetic response of this grating. Closed-form and analytical expressions are presented for the reflection coefficients of zeroth diffracted order and also higher diffracted orders. The proposed method is verified against full-wave simulations and the results are in excellent agreement. Thanks to the...