@article {211969, title = {Design and simulation of all-optical logic gates based on two-dimensional photonic crystals}, journal = {Journal of Optics (India)}, year = {2022}, author = {Asmaa M. Masoud and Ibrahim S. Ahmed and Sahar A. El-Naggar and Mina D. Asham} } @article {211972, title = {Tunable filter based on one-dimensional photonic crystal including nanocomposite material}, journal = {THE EUROPEAN PHYSICAL JOURNAL D}, volume = {76:50}, year = {2022}, pages = {1-9}, author = {Hatem H. Rashwan and Mostafa, Samia and Enas H. Elkhawas and Sahar A. ElNaggar} } @article {212003, title = {A Mathematical Model for the Coronavirus Spread, A Case Study of Egypt}, journal = {Journal of the Egyptian Mathematical Society}, volume = {29:13}, year = {2021}, pages = {1-16}, author = {Assem S. Deif and Sahar A. ElNaggar} } @article {211970, title = {Stochastic modeling of 2D photonic crystals}, journal = {Optical and Quantum Electronics volume}, volume = {53 (261)}, year = {2021}, pages = {1-11}, author = {Wafa, Mohamed I and Yasser M. ElBatawy and Sahar A. El-Naggar} } @article {205386, title = {Highly Sensitive Refractive Index Sensor for Temperature and Salinity Measurement of Seawater}, journal = {Optik}, volume = {216}, year = {2020}, pages = {164901}, author = {Soniya Akter and Kawsar Ahmed and Sahar A. El-Naggar and Sofyan A. Taya and Truong Khang Nguyen and Vigneswaran Dhasarathan} } @article {205391, title = {Numerical analysis of tunable defect mode in cylindrical photonic crystals configuration}, journal = {Microwave and Optical Technology Letters}, volume = {62}, year = {2020}, pages = {3351-3358}, author = {Sahar A. ElNaggar and Truong Khang Nguyen and Vigneswaran Dhasarathan} } @article {205385, title = {Optical fiber surrounded by a graphene layer as an optical sensor}, journal = {Optical and Quantum Electronics}, volume = {52}, year = {2020}, pages = {187}, author = {Noor E. Al-Ashi and Sofyan A. Taya and Sahar A. El-Naggar and D. Vigneswaran and I. S. Amiri} } @article {205384, title = {Properties of defect modes in cylindrical photonic crystals}, journal = {Optik}, volume = {200}, year = {2020}, pages = {163447}, author = {El Naggar, SA} } @article {205392, title = {Stochastic analysis for one dimensional photonic crystals}, journal = {Optik}, volume = {208}, year = {2020}, pages = {164106}, author = {Wafa, Mohamed I and Yasser M. ElBatawy and Sahar A. ElNaggar} } @article {145930, title = {Evolution of Phononic Band Gaps in One-Dimensional Phononic Crystals that Incorporate High-Tc~Superconductor and Magnetostrictive Materials}, journal = {Journal of Superconductivity and Novel Magnetism}, volume = {30}, year = {2017}, pages = {2711{\textendash}2716}, author = {Arafa H. Aly and Ahmed Mehaney and Sahar A. ElNaggar} } @article {145924, title = {Optical guidance in cylindrical photonic crystals~}, journal = {Optik}, volume = {130}, year = {2017}, pages = {584-588}, author = {Sahar A. ElNaggar} } @article {145912, title = {Photonic gaps in one dimensional cylindrical photonic crystal that incorporates single negative materials}, journal = {European Physical Journal D}, volume = {71:11}, year = {2017}, author = {Sahar A. ElNaggar} } @article {145931, title = {Terahertz tunable reflectance of extrinsic photonic crystals by external magnetic field}, journal = {European Physical Journal D}, volume = {71}, year = {2017}, pages = {310}, author = {Sahar A. ElNaggar} } @article {145915, title = {Tuning the flow of light in two-dimensional metallic photonic crystals based on Faraday effect}, journal = {Journal of Modern Optics}, volume = {64}, year = {2017}, pages = {74{\textendash}80}, author = {Arafa H. Aly and Hussein A. Elsayed and Sahar A. ElNaggar} } @article {103992, title = {Tunability of two dimensional n-doped semiconductor photonic crystals based on the Faraday effect}, journal = {OPTICS EXPRESS}, volume = {23}, year = {2015}, pages = {15038- 15046}, author = {Arafa H. Aly and Sahar A. ElNaggar and Hussein A. Elsayed} } @article {103991, title = {Tunable terahertz omnidirectional photonic gap in one dimensional graphene based photonic crystals}, journal = {Optical and Quantum Electronics}, volume = {47}, year = {2015}, pages = {1627{\textendash}1636}, author = {Sahar A. ElNaggar} } @article {103989, title = {Two dimensional tunable photonic crystals and n doped semiconductor materials}, journal = {Materials Chemistry and Physics}, volume = {160}, year = {2015}, pages = {221-226}, author = {Hussein A. Elsayed and Sahar A. ElNaggar and Arafa H. Aly} } @article {60502, title = {Maximization of Photonic Bandgaps in Two-Dimensional Superconductor Photonic Crystals}, journal = {Journal of Superconductivity and Novel Magnetism}, volume = {27}, year = {2014}, pages = {1615{\textendash}1621}, author = {S. A. EL-NAGGAR and H. A. Elsayed and A. H. Aly} } @article {60507, title = {The properties of cutoff frequency in two-dimensional superconductor photonic crystals}, journal = {Journal of Modern Optics}, volume = {61}, year = {2014}, pages = {1064-1068}, author = {A. H. Aly and H. A. Elsayed and S. A. EL-NAGGAR} } @article {44784, title = {Thermal properties and two-dimensional photonic band gaps}, journal = {Journal of Modern Optics}, volume = {61}, year = {2014}, pages = {385-389}, author = {H. A. Elsayed and S. A. EL-NAGGAR and A. H. Aly} } @article {21295, title = {Enlarged omnidirectional photonic gap in one dimensional ternary plasma photonic crystals that contain metamaterials}, journal = {THE EUROPEAN PHYSICAL JOURNAL D}, year = {2013}, abstract = {

In contrast to most of the previous work that has been devoted to the enlargement of omnidirectional
band gap (OBG) originating from Bragg scattering, we address the enlargement of zero-effectivephase
(zero-ϕ) gap arising in one dimensional photonic crystals (1DPCs) that contain alternating single
negative materials. In this article, we propose a new structure termed ternary plasma PCs (TPPCs) by introducing
a thin un-magnetized plasma layer between the two single negative materials in each period. The
influences of plasma thickness, plasma frequency and collision frequency on the gap width are discussed.
Numerical results show that TPPCs structure has wider OBG than that of the corresponding binary PCs.
Moreover, the gap width can be continually enlarged by tuning the plasma layer parameters. The proposed
structure promises to improve filters, switches and other devices in the microwave range.

}, author = {S. A. EL-NAGGAR} } @article {21294, title = {Properties of defect modes in one-dimensional photonic crystals that contain single negative materials}, journal = {Optical Engineering}, volume = {52}, year = {2013}, pages = {024602-1-8}, abstract = {

We examine the properties of the defect modes arising in the
zero-effective phase (zero-φ) gap when a dielectric defect layer is introduced
in a one-dimensional photonic crystal containing single negative
materials. We show that the defect modes inside the zero-φ gap can be
as sensitive to the incidence angle as those inside the Bragg gap. In addition,
adjusting the properties of the dielectric defect layer can control the
frequencies and the number of defect modes. We present a brief design of
a polarization-independent spatial filter based on those defects. The proposed
spatial filter can work at dual carrier frequencies with low-pass and
wide-pass characteristics. Our results can help improve the performance
of microwave devices independent of the source wave polarization

}, author = {S. A. EL-NAGGAR} } @article {21292, title = {Complete band gaps of phononic crystal plates with square rods}, journal = {Ultrasonics}, volume = {52}, year = {2012}, pages = {536{\textendash}542}, author = {S. A. EL-NAGGAR and S. I. MOSTAFA and NH Rafat} } @article {21290, title = {Dependency of the photonic band gaps in two-dimensional metallic photonic crystals on the shapes and orientations of rods}, journal = {Optical Engineering}, volume = {51}, year = {2012}, pages = {068001-1-8}, abstract = {

Photonic bands in two types of two-dimensional metallic photonic
crystals (2-D MPCs), which are composed of dielectric rods embedded
into a metallic background (type I MPCs) and metallic rods in a dielectric
background (type II MPCs), are investigated theoretically using a method
based on the frequency-dependent plane-wave expansion method. We
discuss the maximization of the normalized gap width as a function of
the rod shapes and orientations. In addition, we study the effect of dielectric
constants of the rods and the background on the width of the photonic
band gap. Four different shapes of rods{\textemdash}square, circular, diamond, and
rectangular{\textemdash}are considered. The numerical results show that the type I
MPCs have a higher normalized gap width than the type II MPCs. We
observe that the rotation of the noncircular rods in the type I MPCs
leads to a slight variation, less than 10\%, in the normalized values of
the gap width in the two lattice structures. However, rotating the metallic
square rods arranged in a square lattice results in doubling of the normalized
gap width. The normalized gap width can be tailored by changing the
dielectric constant of the rods (background) in type I (type II) MPCs

}, author = {S. A. EL-NAGGAR} } @article {21289, title = {One-dimensional metallic-dielectric (Ag/SiO2) photonic crystals filter for thermophotovoltaic applications}, journal = {Renewable Energy}, volume = {45}, year = {2012}, pages = {245-250}, abstract = {

In this article, the performance of one dimensional metallic-dielectric photonic crystals (1D MDPCs) filter
for improving the performance of thermophotovoltaic (TPV) systems is studied. The reflectance and
absorbance of Ag/SiO2 filters are calculated using the transfer matrix method. The spectral efficiencies
and the above-bandgap transmissions of the filters are calculated for different choices of number of
periods and layer thicknesses. Furthermore, an optimized stack design that exhibits better spectral
efficiencies and better above-bandgap transmission is presented.

}, author = {S. I. MOSTAFA and NH Rafat and S. A. EL-NAGGAR} } @article {21293, title = {Robust wide zero-average-index gap in photonic heterostructures that incorporate left-handed materials}, journal = {Physica B}, volume = {407}, year = {2012}, pages = {3982{\textendash}3986}, abstract = {

In this article, we theoretically study electromagnetic waves that propagate in a one-dimensional
photonic heterostructure that contains left-handed materials. We suggest a type of heterostructure that
is composed of two photonic crystals (PCs) that consist of different materials, rather than the previously
studied heterostructures that are based on changing the thicknesses of alternating layers, to target
zero-average-index gap enlargement. Numerical calculations of the transmittance show that the
suggested structure possesses an ultra-wide zero-average-index gap that is robust for both transverse
electric and magnetic polarizations. The demonstrated wide gap is independent of the incidence angle.
The proposed structure works as a perfect stop-band filter, which completely blocks both polarizations,
and may have many other potential applications.

}, author = {S. A. EL-NAGGAR} } @article {20782, title = {Design of photonic band gaps in one-dimensional SiO2/a-Si photonic crystals}, journal = {JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS}, volume = {13}, year = {2011}, pages = {781 - 785}, abstract = {

We theoretically study one dimensional binary SiO2/a-Si photonic crystals taking into consideration the dissipative nature of
amorphous Si. We suggest a method namely; {\textquotedblleft}modified thickness{\textquotedblright} to control the band gaps central frequencies by
gradually changing the width of the alternating layers. We calculate the reflectance, transmittance and absorbance of light
based on the transfer matrix method. Calculations show that photonic band gaps can occur at the suggested central
frequency and its multiples. We discuss the limitations on the choice of the first central band gap frequency, thickness of
the a-Si layers and number of periods.

}, author = {S. A. EL-NAGGAR and NH Rafat and S. I. MOSTAFA} } @article {20784, title = {Modeling of a wide band pass optical filter based on 1D ternary dielectric{\textendash}metallic{\textendash}dielectric photonic crystals}, journal = {JOURNAL OF OPTICS}, volume = {13}, year = {2011}, pages = {085101 (8pp)}, abstract = {

We suggest ternary structures of dielectric{\textendash}metal{\textendash}dielectric photonic structures to be used as
optical band pass filters. We theoretically study and evaluate the optical properties of these
one-dimensional structures. ZnSe/metal/LiF and SiC/metal/SiO2 with three metals, namely
silver, gold and copper, are suggested as the optical filters. We calculated the reflectance and the
transmittance of electromagnetic waves (EMW) out of these structures using the transfer matrix
method. These calculations take place for the case of normal and oblique incidences using
actual measured values for the indices of refraction. Our calculations show that such photonic
crystal (PC) filters have a well shaped pass band in the visible range and block efficiently
ultraviolet and infrared EMW. Our results show that PCs having silver as the metal layer are
preferred to those having gold and copper because of the high transmittance in the visible range.
A SiC/Ag/SiO2 filter shows better performance than a ZnSe/Ag/LiF one from the transmittance
and the shape of the band points of view. Such a filter shows a well shaped wide band over the
range of incident angles from 0{\textopenbullet} to 80{\textopenbullet}.

}, author = {NH Rafat and S. A. EL-NAGGAR and S. I. MOSTAFA} } @article {20781, title = {A Rigorous, Coupled-Wave Transfer Matrix Method for Two-Dimensional Threshold Analysis of Distributed Feedback Semiconductor Lasers}, journal = {Journal of Computational Electronics}, volume = {3}, year = {2004}, pages = {67{\textendash}80}, abstract = {

A rigorous, truly two-dimensional method for threshold analysis of distributed feedback (DFB) lasers
based on a coupled wave transfer matrix formalism is presented. The method makes it possible to systematically
study the effect of the various structural and material properties parameters of the laser on the threshold gain and
lasing frequency. Since the optical fields inside and outside the laser are very accurately represented in our analysis,
the small differences in gain of pairs of longitudinal laser modes symmetrically located on both sides of the gap can
be more accurately calculated than in any previous work. The analysis is applicable to gratings of any shape for both
the TE and TM modes, but numerical results are given only for first-order gratings with rectangular and triangular
tooth-shape. Reflectivities of the laser end facets have been calculated from first principles in some typical cases
rather than treated as given parameters.

}, author = {Ahmed A. Abouelsaood and S. A. EL-NAGGAR} } @article {20780, title = {Shape and Size Dependence of the Anti-Reflective and Light-Trapping Action of Periodic Grooves}, journal = {PROGRESS IN PHOTOVOLTAICS: RESEARCH AND APPLICATIONS}, volume = {10}, year = {2002}, pages = {513-526}, abstract = {

The shape and size dependence of the anti-reflective and light-diffusing properties of
surfaces with linear periodic grooves is studied. Grooves of triangular or rectangular
cross-sections on the front or back surface of a crystalline silicon layer are considered.
Our method is an extension of the rigorous, two-dimensional, coupled-wave,
electromagnetic analysis of TE modes in dielectric relief gratings to the case of multilayer
systems with both TE and TM modes through the use of a generalized transfer
matrix formalism. Surfaces with shallow, sub-micrometre rectangular grooves have
substantial anti-reflective and light-diffusing actions contrary to geometric optics
results. Surfaces with sub-micrometre triangular grooves are less efficient antireflectors
and light diffusers than we expect from geometric optics predictions, which
are slowly approached as the period increases. Light diffusion is totally absent for
grooves of either types with a period K \< 02 lm. Front-surface rectangular grooves
of period 065 mm and height 02 mm lead to an absorbance enhancement in the infrared
part of the solar spectrum comparable to that achieved with practical 705 triangular
grooves. Back-surface rectangular grooves lead to some improvement
compared with flat surfaces, but are somewhat inferior to back-surface triangular
grooves.

}, author = {Ahmed A. Abouelsaood and Sahar A. ElNaggar and M. Y. Ghannam} } @proceedings {47671, title = {Investigation of the photogenerated current in V-Grooved textured thin solar cells using two dimensional optical generation and collection}, journal = {16th European Photovoltaic Solar Energy Conference and Exhibition}, year = {2000}, address = {Glasgow 1-5 may 2000}, author = {Rafat, N and El-Naggar, S and Abouelsaood, AA and M.Y.Ghannam} } @article {47669, title = {Analytical study of carrier photogeneration and photocurrent in thin silicon solar cells with specular and diffuse back reflector}, journal = {IEEE Transactions on Electron Devices}, volume = {46}, year = {1999}, pages = {2072}, author = {M. Y. Ghannam and S.El-Naggar and N.Rafat and Abouelsaood, AA} }