این پایان نامه به زبان انگلیسی، مربوط به دپارتمان مهندسی برق و
الکترونیک دانشگاه لیدز انگلستان (University of Leeds) میباشد که در
سال 2012 انجام و با رتبه عالی مورد تایید قرار گرفته است است.
دسته بندی: فنی و مهندسی »
برق، الکترونیک، مخابرات
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توضیحات:
این پایان نامه به زبان انگلیسی، مربوط به دپارتمان مهندسی برق و
الکترونیک دانشگاه لیدز انگلستان (University of Leeds) میباشد
که در سال 2012 انجام و با رتبه عالی مورد تایید قرار گرفته است
است.
Abstract
Surface plasmon polaritons are highly confined electromagnetic
waves which can be employed in developing miniaturised optical
devices for bridging the size-mismatch between the nanoscale
electronics and large diffraction-limited photonic devices. For
this purpose, it is desired to develop silicon compatible plasmonic
devices in order to achieve seamless integration with electronics
on the silicon-on-insulator platform. Plasmonic devices such as
modulators, detectors, couplers, (de)multiplexers, etc, would
possess the advantages of having a small device footprint, low
cost, low power consumption and faster response time. In this
thesis, different silicon-based plasmonic devices were investigated
using finite element simulations, including optical modulators,
couplers and splitters. A metallised stub filled with SiGe/Ge
multiple quantum wells or quantum dots in a silicon matrix, coupled
to a dielectric waveguide was investigated. The modulation
principles include ’spoiling’ of the Q factor and conversion of the
electromagnetic mode parity, due to variation of the absorption
coefficient of the stub filling. A CMOS compatible
interference-based Mach-Zehnder modulator with each arm comprising
a metal-insulator-semiconductor-insulator-metal structure, and a
simpler single arm variant, were considered for electro-optic and
electroabsorption modulation respectively. The electron density
profiles in bias-induced accumulation layers were calculated with
the inclusion of size-quantisation effects at the oxide-silicon
interfaces. These were then used to find the complex refractive
index profiles across the structure, in its biased and unbiased
states, and eventually the modulator insertion loss and extinction
ratio, and their dependence on various structural parameters.
Finally, a silicon-based plasmonic nanofocusing coupler was
investigated, which comprised symmetric rectangular grooves
converging towards a central metal-silicon-metal nano-slit at the
apex of the structure. The structure was optimised to achieve
maximum coupling of light incident from a wide input opening, and
coherent excitation and focusing of surface plasmons as they
propagate towards the nano-slit waveguide. Application of the
nanofocusing structure to achieve simultaneous coupling and
splitting was also investigated, whereby incident light was focused
into two nano-slits separated by a metal gap region at the apex.
Such a plasmonic coupler or splitter can be used for coupling light
directly from a wide fibre grating opening into nanoplasmonic
waveguides in future on-chip plasmonic-electronic integrated
circuits, or into the two arms of a plasmonic Mach-Zehnder
modulator.