This thesis is concerned with a detailed study of laser nonlineanties and the implications for multichannel subcamer multiplexed fibre optic systems
In view of the limitations of previously reported analytic treatments of laser nonlinear distortion, a considerable part of the study is dedicated to the development of modelling and analytic tchniques suitable for practical system design and optimisation The single-mode rate equations provide an adequate basis for the analysis of laser intnnsic dynamic distortion and relative intensity noise and their dependence on device parameters and operating conditions
The Volterra series method of nonlinear system theory is then applied and an analytical model is obtained that describes the nonlineanty in the frequency domain by a set of nonlinear transfer functions This method provides a ngorous analytic nonlinear model that takes into account all the intermodulation products up to third-order as determined by the rate equations Moreover, the laser response to the important case of a sum of narrow-band signals is considered and under certain conditions, which are valid for the majority of systems of interest, the intermodulation power spectral density of the distortion products is determined This enables an accurate evaluation of the impact on the overall system performance of laser intrinsic distortion and optimum overall performance is identified after including the noise introduced in the detection process The relative importance of laser intnnsic distortion and clipping-istortion is also examined
Finally, the analytic model is used to investigate design constraints and the overall system performance of relevant SCM systems Case studies are considered that demonstrate the applicability of the method devised