Optical signal processing plays a key role in a high capacity all-optical communication network. Rapid advances in the processing technology offers new solutions to enhance fiber communications. This thesis focuses on the development of new components and techniques for optical signal processing. / The application of optical nonlinearities in fibers and in semiconductor devices is of great importance in different fields of research. In this thesis, we report our findings in the development of new techniques for photonic signal processing. Two different approaches for extinction ratio enhancement of an amplitude-shift keying (ASK) signal have been demonstrated using self-phase modulation in a highly nonlinear bismuth oxide fiber. The differential phase-shift keying (DPSK) modulation format is also receiving much attention owing to its improved receiver sensitivity and its higher tolerance to signal degradation by undesired fiber nonlinearities. We demonstrated all-optical processing of DPSK signals using different nonlinear phenomena in a semiconductor optical amplifiers, a dispersion-flattened highly nonlinear photonic crystal fiber, and a highly nonlinear bismuth oxide fiber. Various application areas including extinction ratio enhancement, amplitude noise reduction, phase noise reduction, wavelength conversion and wavelength multicasting have been realized using four-wave mixing, self-phase modulation, and cross-phase modulation in the optical elements. (Abstract shortened by UMI.) / The birefringent comb filter is an important element in the processing of microwave and optical signals. To increase the flexibility in its operation, it is desirable for the filter to be tunable in both the spectral position and the spacing of the comb. By incorporating an electro-optic phase modulator to control the overall birefringence, the output comb can be rapidly modulated in the spectral domain. We also introduced a new architecture of a dual-pass Lyot filter that offers the highest tunability of the comb spacing at a given number of birefringent fiber elements. Selectivity of the spacing is based on different alignments between the fiber axes in our cascadable scheme. We applied the birefringent comb filter to multi-wavelength laser source generation using either a semiconductor or a fiber-based gain element. By electrical tuning of the birefringence inside a semiconductor optical amplifier ring laser, a waveband switchable multi-wavelength source has been obtained. In an erbium-doped fiber (EDF) laser, multi-wavelength lasing is inhibited at room temperature owing to the homogeneously broadened gain medium. To address this problem, two different types of fiber nonlinearities, stimulated Brillouin scattering and four-wave mixing, are incorporated separately to the EDF laser to provide self-stabilization of the multi-wavelength oscillation. In addition to multi-wavelength source generation, we further applied the birefringent comb filter to multiply the repetition rate of a high-speed pulsed source using the spectral elimination approach. Repetition rate multiplication from 10 to 40 GHz has been simultaneously achieved for four ITU-grid laser sources around 1550 nm, resulting in an aggregate pulse rate of 160 GHz. The phase coherence of the output pulses is also preserved. / Fok, Mei Po Mable. / "August 2007." / Adviser: Chester Shu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1198. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344035 |
| Date | January 2007 |
| Contributors | Fok, Mei-po., Chinese University of Hong Kong Graduate School. Division of Electronic Engineering. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (ix, 216, xxv p. : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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