Optically non-linear multiple quantum wells (MQWs) can be used for regeneration in periodically amplified optical fibre transmission systems, or as the basis of all-optical switches with applications including wavelength conversion. This thesis investigates the use of InGaAsP/InGaAsP MQW devices for regeneration and wavelength conversion in 10 Gb/s to 40Gb/s fibre transmission systems. Computer modelling is used to investigate signal propagation in systems employing soliton signal pulses, and to show that regeneration with suitable MQW devices can result in significant performance improvements. MQW-based wavelength conversion is also modelled. Three non-linear mechanisms are considered: excitonic absorption bleaching (EAB), absorption changes due to the transient electric field changes which occur in devices incorporating MQWs in reverse biased p-i-n junctions, and non-linear polarisation rotation (NPR). EAB-based devices are ion-implanted to increase the speed of the non-linearity, such that they are suitable for ultra-fast operation. High contrast devices are realised through incorporation of non-linear MQWs in asymmetric Fabry-Perot (AFP) cavities. Characterisation experiments are developed to measure the magnitudes and temporal dynamics of optical non-linearities, and experimental results presented for devices based on each mechanism. EAB recovery faster than 6ps and 9dB non-linear reflectivity change are achieved in devices using an ion-implanted MQW in an AFP cavity. Wavelength conversion of a low repetition rate pulse stream is demonstrated in p-i-n and ion-implanted EAB devices. Ion-implanted EAB devices are also used to demonstrate conversion of high repetition rate signals representative of those used in systems applications. Together with the systems modelling, the experimental results form the basis of a final evaluation of the suitability of each of the three mechanisms for use at 10Gb/s to 40Gb/s. The analysis considers fundamental limitations of the mechanisms, and the effort required for further development. Ion-implanted EAB-based devices are concluded to be most promising.

No description available.

No description available.

No description available.

This thesis investigates the use of Semiconductor Optical Amplifiers (SOA) for 10 and 40Gb/s all-optical 3R signal regeneration and wavelength conversion for application to advanced high-speed all-optical WDM networks. Detailed experimental characterisation of the magnitude and the time scales of inter-band nonlinear effects in SOA is carried out. The regenerative properties of SOA gates are theoretically investigated and related to the SOA physical parameters by means of deriving the SOA gate transfer function. A novel configuration for all-optical regeneration based on Polarisation Switching in an SOA-assisted Sagnac Interferometer (PSSI) is proposed and used to demonstrate, for the first time, multi-channel simultaneous 3R regeneration. This scheme allows to significantly enhance the switching frequency of the SOA, demonstrating error-free regeneration of 40Gb/s signal with long PRBS sequences using an SOA with carrier lifetime exceeding 250ps. The reshaping and retiming ability of the scheme are also assessed experimentally at bit-rate of 40Gb/s, to show the largest distortion tolerance range published to date for regeneration. The scheme is also used to demonstrate 40 to lOGb/s demultiplexing. The cascadability of optical regenerators and wavelength converters is also investigated experimentally. The impact of varying the inter-regenerator spacing in transmission with cascaded wavelength conversion and 3R regeneration over transoceanic distances, is experimentally investigated for the first time, using a novel reconfigurable fibre loop. These results show that a trade-off exists between the transmission signal Q-factor and the inter-regenerator spacing, which depends on the regenerator transfer function characteristics, and thus can be predicted from the SOA parameters. In 40Gb/s transmission with optical regeneration it was demonstrated that the use of an optical regenerator before the electrical receiver increases the power margin and maximum error-free transmission distance at 40Gb/s in excess of 100km. Finally a novel concept for multi-channel wavelength conversion and regeneration is presented utilising an integrated SOA array in a novel configuration to demonstrate, for the first time, simultaneous regenerative wavelength conversion of 1 OGb/s signals. This also shows the potential for large scale monolithic integration for optical processing applications in WDM networks.

No description available.

No description available.

No description available.

No description available.

No description available.