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No description available.

Thesis (Ph.D.)--University of Washington.

Thesis (M.S.) in Civil Engineering--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 175-177).

M.Ing. / This thesis covers the theory and development of fused, biconically tapered, fibre-optic couplers and their application in sensors. The optical coupling between fibres is described by means of the coupled-mode theory in the case of a weakly guiding coupler. Firstly, simplified expressions for the guided modes in an optical fibre are derived. This is followed by the derivation of the coupled-mode equations for a perturbed waveguide. The coupled-mode equations are then used, together with the expressions for the guided modes, to determine the coupling coefficient for a weakly guiding coupler. In the case where the coupler is not weakly guiding, a model based on a rectangular dielectric waveguide is presented. A process for the manufacture of fibre-optic couplers, based on the fusion and elongation technique, was developed. This process is described and special attention is paid to the influence which different process parameters has on the properties of the couplers. During the development, the coupling theory was utilized to optimize the process. Results obtained with couplers manufactured by this process, are presented. A specific application of couplers, namely a new type of fibre-optic coupler sensor, was developed. The operation of the sensor relies on the change of the coupling ratio with an axially applied mechanical strain. Analog signal processing of the two outputs yields a signal which is directly proportional to the strain and which is independent of fluctuations of the light source power. The sensor was investigated experimentally by manufacturing temperature and elongation sensors which work on this principle. The operation and features of these sensors are presented, together with very promising experimental results.

Light loss in single mode fiber optical switches is investigated. Loss due to reflection, aberration and fiber misalignment are evaluated. A simple model of image to fiber end face overlap for the fiber/lens system is developed. The intensity distribution of light in the fiber and imaging system is assumed to be gaussian. It was found that aberration is a major cause of loss and that fiber misalignment did not cause as much loss as expected. Loss due to reflection is assumed to be minimal due to the presence of anti-reflection coatings on the optical components. / Master of Science

No description available.

No description available.

An analysis of modal noise in multimode optical fibers was performed. Both spatial and time varying modal noises were analyzed. The time varying modal noise was g.enerated in two ways: the first, by vibrating the optical fiber, the second, by varying the temperature of the optical fiber. Under controlled conditions the temperature of the optical fiber varied between 68°F to 200°F while the fiber was held stationary. The optical fiber was then vibrated while the temperature was held constant. Data indicated that the modal noise statistics agreed with the Beta distribution. The statistics of the spatial modal noise were measured and were then compared to the time varying modal noise. These statistical moments disagreed with the Beta statistics. This indicated that modal noise generated in optical fibers is possibly a non-ergodic process. Next the optical fiber's spatial auto-correlation function and spatial intensity fade statistics were computed.

by Cheong Lik-ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references. / Abstract / Acknowledgments / Chapter Chapter I --- Introduction --- p.1 / Chapter 1.1 --- Definitions of Optical Solitons --- p.1 / Chapter 1.2 --- A Brief History of Optical Solitons --- p.2 / Chapter 1.3 --- Generation of Optical Solitons --- p.4 / Chapter 1.4 --- About the Thesis --- p.6 / References --- p.8 / Chapter Chapter II --- General Theory of Optical Solitons --- p.10 / Chapter 2.1 --- Propagation Equation of Optical Solitons --- p.10 / Chapter 2.2 --- Solving of the NLSE --- p.16 / Chapter 2.2.1 --- Inverse Scattering Transform --- p.17 / Chapter 2.2.2 --- Split-Step Fourier Method --- p.20 / Chapter 2.3 --- Fundamental Solitons --- p.22 / Chapter 2.4 --- Higher Order Solitons --- p.25 / References --- p.27 / Chapter Chapter III --- Modeling of Soliton Generation Systems Part I: Gain Switching and Spectral Windowing --- p.29 / Chapter 3.1 --- General Descriptions --- p.29 / Chapter 3.2 --- About the Gain Switching and Spectral Windowing Method --- p.30 / Chapter 3.3 --- Gain Switching of Semiconductor Laser Diodes --- p.30 / Chapter 3.3.1 --- Rate Equations of Semiconductor Laser Diodes --- p.31 / Chapter 3.3.2 --- Analysis of Gain Switching Pulses --- p.35 / Chapter 3.3.3 --- Propagation of Gain Switching Pulses in Optical Fibers --- p.42 / Chapter 3.4 --- Spectral Windowing --- p.47 / Chapter 3.5 --- Erbium-Doped Fiber Amplifier --- p.50 / Chapter 3.5.1 --- Theoretical Model of Erbium-Doped Fiber Amplifier --- p.51 / Chapter 3.5.2 --- Pulse Evolutions in Erbium-Doped Fiber Amplifier --- p.54 / Chapter 3.5.3 --- Analysis of Amplification for Gain Switching Pulses --- p.55 / Chapter 3.6 --- Optimal Condition for the Gain Switching and Spectral Windowing Method --- p.60 / References --- p.61 / Chapter Chapter IV --- Modeling of Soliton Generation Systems Part II: Fiber Ring Laser --- p.64 / Chapter 4.1 --- General Descriptions --- p.64 / Chapter 4.2 --- About the Fiber Ring Laser Method --- p.65 / Chapter 4.3 --- Principles of the Fiber Ring Laser --- p.66 / Chapter 4.4 --- Mathematical Model of the Fiber Ring Laser --- p.67 / Chapter 4.4.1 --- Cross Phase Modulation --- p.68 / Chapter 4.4.2 --- Evolution Equations in Ordinary Optical Fibers --- p.70 / Chapter 4.4.3 --- Evolution Equations in Erbium-Doped Fibers --- p.71 / Chapter 4.4.4 --- Description of Polarization Controllers --- p.72 / Chapter 4.5 --- Analysis of Optical Pulses Generated from Fiber Ring Lasers --- p.74 / Chapter 4.5.1 --- Properties of the Mode Locking Process --- p.74 / Chapter 4.5.2 --- Pulse Width Analysis --- p.79 / Chapter 4.5.3 --- Constant Pulse Width Analysis --- p.88 / Chapter 4.5.4 --- Self-Starting Process --- p.91 / Chapter 4.6 --- Stimulated Raman Scattering in Fiber Ring Lasers --- p.94 / Chapter 4.6.1 --- Mathematical Descriptions of Stimulated Raman Scattering --- p.95 / Chapter 4.6.2 --- Effects of Stimulated Raman Scattering on Fiber Ring Lasers --- p.98 / Chapter 4.7 --- Comparison of the Two Methods --- p.100 / References --- p.102 / Chapter Chapter V --- Experimental Investigation of Fiber Ring Lasers --- p.105 / Chapter 5.1 --- Experimental Setup --- p.105 / Chapter 5.2 --- Experimental Results --- p.106 / Chapter 5.3 --- Discussions --- p.117 / References --- p.122 / Chapter Chapter VI --- Conclusion --- p.123 / Chapter Chapter VII --- Future Extensions --- p.127 / Appendix I Solving the NLSE by the Inverse Scattering Transform --- p.A1 / Appendix II Solving the NLSE by the Split-Step Fourier Method --- p.A9 / Appendix III Parameter Listing --- p.A12