Design Considerations for an Optical PSK Homodyne Receiver

[摘要] This thesis presents studies concerned with the design of an optical homodyne PSK receiver. Fundamental receiver sensitivities for a number of optical detection schemes are presented. The principal of performance degradation due to finite phase error in the detection process is established. The major noise source in semiconductor lasers is considered, lineshape anomalies, which may affect coherent communication systems, outlined, and methods for laser phase noise reduction discussed. An experimental technique for the measurement of laser phase noise is implemented, and results from free running lasers presented. Techniques for linewidth reduction are investigated and results given. An analysis of the optical Costas loop, an optimum solution of PSK detection, is presented. Performance in the presence of non-negligible phase noise is considered. Equivalent noise bandwidth integrals are evaluated for a number of loop filter functions, and a design procedure for a second order loop incorporating an active lead-lag filter derived. Consideration is then given to system operation in the presence of significant loop propagation delay. A model of the system is developed and results presented for beat linewidths typical of a number of common laser sources. A number of components necessary for the implementation of the Costas loop are developed. These include a wideband detector/amplifier module, and a phase modulator. Consideration is also given to the design of a 90

[发布机构] University:University of Glasgow

[关键词] Electrical engineering