A review on the characterisations of photonics devices by using the frequency domain modal solution, junction analysis
and beam propagation methods and additionally time-domain approach, but all based on the numerically efficient finite
element method is presented. Numerically simulated results for various photonic devices such as uniform optical
waveguides, photonic crystal fibres, high-speed optical modulators, spot-size converters, compact power splitters, metalclad
terahertz waveguides, photonic crystals and nonlinear acousto-optical interactions in optical waveguide are
The H-field finite element method (FEM) based full-vector formulation is used in the present work to study the vectorial
modal field properties and the complex propagation characteristics of Surface Plasmon modes of a hollow-core dielectric
coated rectangular waveguide structures, and graphene based structures. Additionally, the finite difference time domain
(FDTD) method is used to estimate the dispersion parameters and the propagation loss of such waveguides and devices.
A rigorous full-vectorial modal solution approach based on the finite element method is used to find the propagation properties of terahertz (THz) waveguides, such as photonic crystal fibers, quantum cascaded lasers, plasmonic waveguides, power splitters, and narrow-band filters. Design approaches to reduce the modal loss due to the material and leakage loss in photonic crystal fibers and in metal-coated hollow-glass plasmonic waveguides have also been considered. The plasmonic confinement and gain threshold of quantum cascaded lasers used as THz sources and the chromatic dispersion in plasmonic waveguides are also presented.
A rigorous full-vectorial modal solution approach based on the finite element method is used to find the propagation
properties of THz waveguides. Design approaches are presented to reduce the modal loss. Design of several THz
devices, including quantum cascade lasers, plasmonic waveguides, power splitters and narrow-band filters are also
The optical properties of a nanoscale silicon slot-waveguide has been rigorously studied by using a full vectorial H-field
finite element method (VFEM) based approach and presented in this paper. The variations of effective indices, effective
areas, power densities in the slot-region and the confinement factors of the slot waveguide, with both horizontal and
vertical slots, are thoroughly investigated for quasi-TM and TE modes. The full vectorial magnetic and electric field
profiles, and Poynting vector (Sz) are also presented.
In this paper a low-loss hollow-core rectangular plasmonic waveguide with a dielectric coating of Te
on is analyzed
for terahertz propagation using a full-vectorial nite element method (FEM). It has been identied that, in
contrast to the fundamental Hx10 mode, the Hx12 mode shows interesting modal properties and oers the lowest
possible loss for the structure after introducing the dielectric coating. This mode also tends to yield a near-Gaussian eld prole when the dielectric coating thickness is optimized and then it will be easy to couple
to a Gaussian shaped source. The optimization of the loss values has been evaluated by comparing the loss
characteristics for dierent dielectric materials and also by using dierent metal claddings.
In this paper, the power confinement and the power density in the slot region of a vertical and horizontal slot waveguide
are optimized; full-vectorial H and E-field profiles along with Poynting vector are also shown for both of these silicon
waveguides. Bending loss of such slot waveguides is also presented.
Vectorial modal field profiles and the complex propagation characteristics of Surface Plasmon modes in optical and THz
guided wave structures are presented by using a H-field based finite element method. It is shown here that by
engineering the metal electrode mode selectivity in a Quantum cascade laser can be enhanced. Additionally, it is also
shown that by introducing Teflon coating, the propagation loss of a hollow-core rectangular waveguide can be
Rigorous modal solutions of silicon nanowires are presented by using a H-field based finite element formulation. It is
shown that beam profiles of a circular nanowire are not circular. It is also shown that most of the optical power in a
silicon slot waveguide can be confined in the low-index slot region. It is shown here that dispersion properties can be
easily controlled by waveguide design of silicon nanowires, as waveguide dispersion dominates over the material
dispersion for such sub-wavelength optical structures. Bending losses of such silicon nanowires are also presented.
When the cross-section of an optical waveguide is much smaller than the operating wavelength, unique materials and
structural dependent properties can be observed. In this regard silicon has been particularly attractive as the low-cost and
mature CMOS fabrication technology widely used in the electronics industry can be exploited. The high index contrast
of silicon allows light confinement in submicron size waveguides, along with the creation of very compact bends, to
allow increased functionality of photonic integrated circuits. A rigorously H-field based vectorial modal analysis has
been carried out, which can more accurately characterize the abrupt dielectric discontinuity of a high index contrast
optical waveguide. As a result, the full-vectorial H and E-field and the Poynting vector profiles are shown in detail. The
work done and reported reveals that the mode profile of a circular silicon nanowire is not circular and also has a strong
axial field component. Arising from the results of the analysis, the characteristics of single mode operation, the vector
field profiles, the modal ellipticity and the group velocity dispersion of this silicon nanowire both circular and planar are
presented. The modal hybridness and birefringence of rectangular silicon nanowires and slot-type waveguides are also
A modal solution approach based on a rigorous full vectorial finite element method has been used to determine single
mode single polarization properties of a bent highly birefringent fiber photonic crystal fiber. A design approach for the
single mode single polarization design has been discussed.
Surface plasmons are confined to the surfaces which interact strongly with the electromagnetic waves.
They occur at the interfaces where the relative permittivities of the bounding materials are of opposite
sign. It is well know that some metals and highly doped semiconductor shows highly negative
relative permittivity and such a structure with a dielectric cladding can support surface plasmon
modes. These modes decay exponentially, they can be highly localised and can also be confined
inside a sub-wavelength size guided wave structure. A rigorous full vectorial finite element-based
approach has been developed to characterize a wide range of plasmonic devices, both at optical and
terahertz frequencies. Results for wave confinement in quantum cascaded lasers for terahertz (THz)
frequencies and metal coated photonic crystal fibres are presented.
Compact Quantum Cascade Laser waveguides have been analyzed using the full-vectorial finite element method. Modal
intensity profiles, detailed power confinements and loss factors have been characterized for waveguides based on
GaSb/AlGaSb multiple quantum well structures. Variations in these key parameters were also further investigated whilst
varying the semiconductor doping concentration. Higher order modes having a low propagation loss were also shown.
A modal solution approach based on the powerful, full-vectorial, H-field based finite element method (FEM) has been
used to analyze the single mode operation of a PCF. Modal solutions of the fundamental modes of highly birefringent
PCFs have been obtained. The FEM with perfectly matched layer condition has been used to characterize the leakage
loss and the differential loss between the polarized modes of PCFs. The design of a single-mode single-polarization
PCF has also been proposed.
A modal solution approach, based on a powerful, full-vectorial, H-field based finite element method (FEM), has been
used to analyze the single mode operation of a PCF and the modal solution of the fundamental space filling mode has
been analyzed. The FEM with perfectly matched layer condition has been used to characterize the leakage loss of a PCF
and the differential loss between the polarized modes of a PCF and as a result, the design of a single mode single
polarization PCF has also been proposed.
The emergence of terahertz (THz) technology has opened up a new frontier of fundamental research with many novel
applications, such as in imaging and spectroscopy. For these fibers, the waveguiding parameters are easily controllable,
when compared to conventional all silica optical fibers and recently there has been an initiative to use such waveguides
for guiding THz frequencies. In this context, A rigorous full-vectorial finite element method has been used to obtain the
modal solutions of simple, high-density polystyrene dielectric waveguides along with their propagation constants,
attenuation characteristics, vectorial modal field profiles, the spot-size and the modal hybridness.
Finite element-based rigorous full-vectorial modal solution approach has been developed to calculate the effective index
of the fundamental space filling mode, cutoff condition of the fundamental and the second guided modes to identify the
single mode operation ranges for the photonic crystal fiber. The single mode operation regime for a Terahertz photonic
crystal fiber has also been discussed.
A finite element-based, rigorous full-vectorial modal solution approach has been developed to calculate the effective
index of the fundamental space filling mode, the cut-off condition of the fundamental and the second guided modes to
identify single mode operation ranges for a photonic crystal fiber design. Furthermore, structural asymmetry has been
introduced in the model to maximise the modal birefringence to create a design for polarization maintaining photonic
Brewster angle technique has been recently well developed for the transparent anisotropy materials. In this paper, the Brewster angle for an absorbing biaxial medium is characterized using a cubic equation. It has been shown that there are infinite possible orientations for which the Brewster angles can be measured in absorbing crystals. The numerically simulated results were compared with available experimental data of the semiconductor CdSe. This theoretical investigation leads to the numerical solution of the refractive index parameters using the Brewster angle technique in uniaxial crystals.