Modelling of an optical time division demultiplexer.

The communication Networks of the future will require signal switching in the optical domain to avoid the inherent speed bottleneck of optical-electronic-optical conversions. This has resulted in an intense research effort in this area. Of particular interest are wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM). The latter offers the advantage that it operates over a single wavelength, removing the problems associated with dispersion in fibre systems whilst the former operates over a number of wavelengths. This thesis concentrates on the modelling and simulation of one particular system: the asymmetric semiconductor laser amplifier loop mirror (ASLALOM) for OTDM.Initially, a literature review looks at the theory of laser operation which complements the following chapter on laser amplifiers. A review of current optical switching devices will be examined next with regard to switching speeds, crosstalk and the possibility of integration. Also wavelength division multiplexing and time division multiplexing are reviewed, comparing the different systems in current use.At the present time, no complete models of an asymmetric semiconductor laser amplifier loop mirror have been developed. The intention of this work is to determine the equations necessary for a model to be developed and thus enable the system to be simulated. Computer modelling of a system prior to implementation is advantageous in all aspects of engineering. As this system is still confined to the laboratory a model would complement any practical work and identify critical design parameters.In this work the Travelling Wave Semiconductor Laser Amplifier (TWSLA) is first modelled in a form which is appropriate for the asymmetric semiconductor laser amplifier loop mirror architecture. The simulations are then used to demonstrate the switching speeds for different configurations and identify any areas needing further work, such as crosstalk, birefringence and polarisation, a method for multi-channel output is also presented. A further aim is to lay a foundation for future work to enable the system to be fully characterised with regard to noise, dispersion and integration.