Title: Semiconductor Optical Amplifier.
Author : Engy Khalil Ibrahim El-Nayal
Collection : Ph.D. Electrical
Abstract:
This research is in the area of high speed telecommunication systems where all-optical technologies are being introduced to meet the ever increasing demand for bandwidth by replacing the costly electro-optical conversion modules. In such systems, all-optical routers are the key technologies capable of supporting networks with high capacity/bandwidth as well as offering lower power consumption. One of the fundamental building blocks in all-optical routers/networks is the semiconductor optical amplifier (SOA), which is used in for clock extraction, wavelength conversion, all-optical gates and optical processing. The SOAs are perfect for optical amplification and optical switching at a very high speed. This is due to their small size, low switching energy, non-linear characteristics and the seamless integration with other optical devices. Therefore, characterization of the SOA operational functionalities and optimization of its performance for amplification and switching are essential and challenging. One of the most crucial issues to consider in the SOAs analysis is the amplified spontaneous emission (ASE) noise because it strongly affects the performance evaluation of transmission systems featuring these devices. The main source of ASE noise in the optical field in a semiconductor optical gain medium is the spontaneous emission of photons by recombination of electron-hole pairs. A number of schemes have been proposed to evaluate the optical signal to noise ratio (OSNR) and the noise figure (NF) of SOAs theoretically and experimentally. Different approaches have also been used to describe the effects of ASE noise on the quality of the optically generated electrical signals theoretically. This thesis addresses the impact of ASE noise and its effect on the behavior and the performance of SOA especially on the signal gain. A SOA model is been developed and used throughout the investigation for theoretical simulations. Because of no work has been reported on the SOA for improving the gain uniformity under the influence of ASE noise, therefore the gain standard deviation is proposed to measure the SOA gain uniformity at high speed data rates (10 Gb/s). This research also aims to characterize the boundary conditions to optimize the SOA performance for amplification and switching. Results show that the optimum conditions required to achieve the maximum output gain for best amplification performance depends on the SOA peak gain wavelength. It is also shown that the optimum phase shift of 1800 for switching can be induced at lower input power level when the SOA biasing current is at its maximum limit.
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