Sahar El-Naggar

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.

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

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—square, circular, diamond, and
rectangular—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

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.