204 research outputs found
A modal model for diffraction gratings
A description of an algorithm for a rather general modal grating calculation
is presented. Arbitrary profiles, depth, and permittivity are allowed. Gratings
built up from sub-gratings are allowed, as are coatings on the sidewalls of
lines, and arbitrary complex structure. Conical angles and good conductors are
supported
Supermodes of Hexagonal Lattice Waveguide Arrays
We present a semi-analytical formulation for calculating the supermodes and
corresponding Bloch factors of light in hexagonal lattice photonic crystal
waveguide arrays. We then use this formulation to easily calculate dispersion
curves and predict propagation in systems too large to calculate using standard
numerical methods.Comment: Accepted by J. Opt. Soc. Am. B, DocID:160522.
http://www.opticsinfobase.org/abstract.cfm?msid=16052
Quasi-Homogeneous Backward-Wave Plasmonic Structures: Theory and Accurate Simulation
Backward waves and negative refraction are shown to exist in plasmonic
crystals whose lattice cell size is a very small fraction of the vacuum
wavelength (less than 1/40th in an illustrative example). Such
``quasi-homogeneity'' is important, in particular, for high-resolution imaging.
Real and complex Bloch bands are computed using the recently developed
finite-difference calculus of ``Flexible Local Approximation MEthods'' (FLAME)
that produces linear eigenproblems, as opposed to quadratic or nonlinear ones
typical for other techniques. FLAME dramatically improves the accuracy by
incorporating local analytical approximations of the solution into the
numerical scheme.Comment: 4 pages, 3 figure
Eigen modes for the problem of anomalous light transmission through subwavelength holes
We show that the wide-spread concept of optical eigen modes in lossless
waveguide structures, which assumes the separation on propagating and
evanescent modes, fails in the case of metal-dielectric structures, including
photonic crystals. In addition to these modes, there is a sequence of new
eigen-states with complex values of the propagation constant and non-vanishing
circulating energy flow. The whole eigen-problem ceases to be hermitian because
of changing sign of the optical dielectric constant. The new anomalous modes
are shown to be of prime importance for the description of the anomalous light
transmission through subwavelength holes.Comment: 5 pages, 4 figure
The Average Body Surface Area of Adult Cancer Patients in the UK: A Multicentre Retrospective Study
The majority of chemotherapy drugs are dosed based on body surface area (BSA). No standard BSA values for patients being treated in the United Kingdom are available on which to base dose and cost calculations. We therefore retrospectively assessed the BSA of patients receiving chemotherapy treatment at three oncology centres in the UK between 1st January 2005 and 31st December 2005
Double-heterostructure cavities: from theory to design
We derive a frequency-domain-based approach for radiation (FAR) from
double-heterostructure cavity (DHC) modes. We use this to compute the quality
factors and radiation patterns of DHC modes. The semi-analytic nature of our
method enables us to provide a general relationship between the radiation
pattern of the cavity and its geometry. We use this to provide general designs
for ultrahigh quality factor DHCs with radiation patterns that are engineered
to emit vertically
Semi-analytic method for slow light photonic crystal waveguide design
We present a semi-analytic method to calculate the dispersion curves and the
group velocity of photonic crystal waveguide modes in two-dimensional
geometries. We model the waveguide as a homogenous strip, surrounded by
photonic crystal acting as diffracting mirrors. Following conventional
guided-wave optics, the properties of the photonic crystal waveguide may be
calculated from the phase upon propagation over the strip and the phase upon
reflection. The cases of interest require a theory including the specular order
and one other diffracted reflected order. The computational advantages let us
scan a large parameter space, allowing us to find novel types of solutions.Comment: Accepted by Photonics and Nanostructures - Fundamentals and
Application
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