Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"Beam propagation method"”.
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Analysing curved optical waveguides using the finite difference beam propagation method
… a program utilising the 3D finite difference beam propagation method, which was created and optimised over the course of the research, to investigate if the different curvature profiles could reduce the loss caused by bends in ridge waveguides. It was found that much lower loss could be …
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Iterative nonlinear beam propagation method and its application in nonlinear devices
In this thesis, an iterative nonlinear beam propagation method is introduced and applied to optical devices. This method is based on Hamiltonian ray tracing and the Wigner distribution function. First, wave propagation simulation using Hamiltonian ray tracing is illustrated and verified with …
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Design and simulation for the fabrication of integrated semiconductor optical logic gates
… and multimode interference (MMI) devices. We use beam propagation method (BPM) to model, design and optimize dilute ridge waveguides, MMIs, and asymmetric twin waveguide (ATG) adiabatic taper couplers. We assess device robustness with respect to variations in fabrication, including lateral pattern …
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Fiber to waveguide couplers for silicon photonics
… technology, we find ourselves in need of methods to seamlessly transfer light between the optical fibers of global scale telecommunications networks and the on-chip waveguides used for signal routing and processing in local computing networks. Connecting these components directly results …
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Towards Direct Writing Of 3-d Photonic Circuits Using Ultrafast Lasers
… mode analysis. Furthermore, a finite-difference beam propagation method for wave propagation in 3D-waveguides is proposed. The photo-structural modifications underlying the changes in the material optical properties after exposure are investigated. The highly nonlinear processes of the …
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Second harmonic generation in novel optical waveguides
… and numerically efficient Finite Element based Beam Propagation Method has been employed to investigate the evolution of Second Harmonic Generation in highly nonlinear SF57 soft glass Equiangular Spiral PCFs. Further, the H-field based Finite Element Method has been employed for the stationary …
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Optical studies of super-collimation in photonic crystals
… of peculiar effects, in particular, the propagation of optical beams without spatial spreading. This effect, called super-collimation (also known as self-collimation), allows diffraction-free propagation of micron-sized beams over centimeter-scale distances. This linear effect is a …
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Electrooptic mach-zehnder modulators in gallium arsenide
… with these slow-wave electrodes. The variational method, effective-index method, and beam propagation method were used to model the propagation of light in these devices, and, hence, obtaining the necessary design parameters for these devices. Based on these numerical simulations, modulators were …
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Direct UV-written waveguide devices
… (±0.5dB) were recorded. Device modelling using Beam Propagation Method (BPM) and an analytical model showed good agreement with experimental results over a broad crossing angle and wavelength range.<br/><br/>By introducing refractive index asymmetry in 2° X-couplers, it was possible to tune the …
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Scalar Scattering Theory and Physics-inspired Optimization for Computational Imaging
… provides a quantitative comparison with other methods to clarify its applicability. It also explores the adjoint method for solving the TIE, which significantly enhances numerical stability, and discusses the analytical relationship between non-paraxial formulations and conventional phase …
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Non-linear optical properties of semiconductor nano-structures for slow light and wavelength conversion
… calculations using the finite-difference beam propagation method in both a quantum dot and quantum well semiconductor optical amplifier. These calculations indicate that the quantum dot device performs better at the powers and speeds of relevance to telecommunications, but that the faster …
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Numerical Analysis of Optically-induced Long-period Fiber Gratings for Sensing Applications
… and analyzed using the finite-difference beam propagation method (FD-BPM). The result shows full conversion for both core-core and core-cladding mode coupling under phase matching condition. Moreover, the sensitivity of OLPG to temperature, axial strain and ambient refractive index is …
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Towards efficient three-dimensional wide-angle beam propagation methods and theoretical study of nanostructures for enhanced performance of photonic devices
… Padé approximant operators for the wide-angle beam propagation method (WA-BPM). Such new operators not only allow a more accurate approximation to the true Helmholtz equation than the conventional operators, but also give evanescent modes the desired damping. We have also demonstrated the …
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Finite element modelling of photonic crystal fibres
… full-vectorial H-field based finite element method (FEM). Besides the modal solutions of the effective indices, mode field profiles, spot sizes, modal hybridness, polarization beat length and group velocity dispersion values for equal and unequal air holes; research was carried out to …
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Characterisation of silicon photonics devices
… a fully vectorial H-field based finite element method has been used to obtain the modal characteristics of high index contrast bent waveguide to get a better understanding of the curved section. Through the beam propagation method, the propagation losses and the spot-size along the propagation …