Wong Wan Yan = 光學中消光截面佯謬之解釋 / 黃蘊殷. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 58-60). / Text in English; abstracts in English and Chinese. / Wong Wan Yan = Guang xue zhong xiao guang jie mian yang miu zhi jie shi / Huang Yunyin. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Scattering of a Plane Wave by an Infinitely Long Cylinder --- p.4 / Chapter 2.1 --- Dielectric cylinder (with no absorption) --- p.8 / Chapter 2.2 --- Perfectly conducting cylinder --- p.10 / Chapter 3 --- Scattering of a Gaussian Beam by a Dielectric Cylinder (Non- Resonance) --- p.13 / Chapter 3.1 --- Configuration and equations used --- p.13 / Chapter 3.2 --- Numerical result and discussion --- p.17 / Chapter 3.2.1 --- a <w --- p.19 / Chapter 3.2.2 --- a>w --- p.21 / Chapter 4 --- Scattering of a Gaussian Beam by a Dielectric Cylinder (Res- onance) --- p.24 / Chapter 4.1 --- Algorithm --- p.26 / Chapter 4.2 --- Numerical result and discussion --- p.28 / Chapter 5 --- Scattering of a Plane Wave by a Conducting Strip --- p.33 / Chapter 5.1 --- Configaration and equations used --- p.34 / Chapter 5.2 --- Numerical calculation --- p.39 / Chapter 5.3 --- Numerical results and discussion --- p.42 / Chapter 6 --- Actual Scattering Cross Section --- p.49 / Chapter 6.1 --- Configaration and Equations used --- p.49 / Chapter 6.2 --- Numerical result and disscusions --- p.51 / Chapter 7 --- Conclusions --- p.56 / Bibliography --- p.58 / Chapter A --- Bessel functions --- p.61 / Chapter B --- A plane wave incident on a single-layered medium --- p.63

Thesis--Ph. D., University of Hong Kong, 1985.

published_or_final_version / Electrical Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 105-107). Also available via the Internet.

No description available.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Includes bibliographical references (leaves 68-69).

Thesis (M.S. in Engineering Acoustics and M.S. in Electrical Engineering)--Naval Postgraduate School, June 1990. / Thesis Advisor(s): Miller, James H. ; Chiu, Ching-Sang ; Yang, Chyan. "June 1990." Description based on title screen as viewed on October 20, 2009. DTIC Identifier(s): Acoustic Tomography, Theses, Range Kutta Fehlberg Method, C Programming Language, Macintosh 2 Computers, Transputers, Parallel Processors, Numerical Integration. Author(s) subject terms: Acoustic Tomography, Ray Tracing, Parallel Processing, Gaussian Beams, Transputers. Includes bibliographical references (p. 122-124). Also available online.

No description available.

This thesis describes the design and implementation of several novel, nanosecond pulsed, intracavity optical parametric oscillators for the generation of terahertz radiation. The application of the intracavity approach in the context of terahertz optical parametric oscillators has been demonstrated for the first time, and the pump wave energy required was thereby reduced by an order of magnitude. The terahertz wave was tunable from under 1THz up to 3THz with a free running linewidth of ~50GHz and pulse energies up to ~20nJ (pulses were a few nanoseconds in duration). The terahertz beam profile was of Gaussian shape and could be focussed down to 2.3 times the diffraction limited spot size (M² values of 2.3 and 6.7 in the components of the beam parallel and perpendicular to the silicon prism array output coupler respectively). Developments of this intracavity source with regard to the linewidth are also reported. Implementation of etalons in the optical (laser and OPO) cavities was shown to be a promising technique that brings the terahertz linewidth down below 1GHz (close to the transform limit of nanosecond pulses) while retaining the tuning range and beam characteristics of the free running system. Close to Fourier transform limited pulses were obtained (<100MHz linewidth) via an injection seeding technique, although with significantly increased system complexity. A deleterious effect caused by the mode beating of a multimode host laser was also discovered, in that sidebands were induced on the seeded downconverted wave. This has wider implications in the field of intracavity OPOs. Finally, quasi-phasematching techniques implementing periodically poled lithium niobate were investigated as a way to lower the downconversion threshold energy requirement (by collinear propagation of the optical waves), and also to extract the terahertz wave rapidly from the (highly absorbing in the terahertz region) lithium niobate crystal. The existence of two phasematching solutions arising from the bidirectionality of the grating vector was identified as a serious design constraint in the context of an OPO where either solution can build up from noise photons, and so prefers the solution with the lowest walkoff of the downconverted waves - possibly resulting in unextractable terahertz radiation. Quasi-phasematching with an orthogonal grating vector (with identical but opposite phasematching solutions) was demonstrated and cascaded downconversion processes observed and characterised. These cascaded processes are permitted by the collinearality of the optical waves and may allow efficiency improvements through overcoming the quantum defect limit. This research has resulted in four peer reviewed papers in respected journals, and the intracavity terahertz OPO has been licensed to a company who have commercialised the technology (M Squared Lasers, Glasgow).

<p>In this report we describe simulation of the surface current density on a PEC cylinder and the diffracted field for a line source above a finite PEC ground plane as a means to verify the Nero2D program. The results are compared with the exact solution and give acceptable errors. A terrain model for a communication link is studied in the report and we simulate the wave propagation for terrain with irregular shapes and different materials. The Nero2D program is based on the fast multipole method (FMM) to reduce computation time and memory. Gaussian sources are also studied to make the terrain model more realistic</p>