الفهرس 
Introduction and Overview of ThesisOnly 14 pages are availabe for public view
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Abstract
The present study is concerned with the all-optical logic gates using semiconductor optical amplifiers (SOAs). The performances of all-optical logic XOR, AND, NOR, OR and NAND gates based on SOAs-Mach–Zehnder interferometer (MZI) have been simulated including the effects of amplified spontaneous emission (ASE). For the parameters used, all-optical logic gates using SOAs are capable of operating at speed of 80 Gb/s. We propose a new scheme to realize all optical logic NAND operating at high
speeds up to 250 Gb/s utilizing the ultrafast phase response during two-photon absorption (TPA) process in SOA. NAND gate is important because other Boolean logic elements and circuits can be realized using NAND gates as basic building blocks. Rate equations for SOAs (for input data signals with high intensity) configured in the form of a MZI have been solved. The input intensities are high enough so that the two-photon induced phase change is larger than the regular gain induced phase change. The performance of this scheme is analyzed by calculating the quality factor of the resulting data streams. The results show that both AND and NAND operations at 250 Gb/s
with good signal to noise ratio are feasible. When the TPA of a high intensity pump beam takes place in a SOA there is an associated fast phase change of a weak probe signal. A scheme to realize fast alloptical XOR logic function using TPA induced phase change has been analyzed. Rate equations for SOA, for input data signals with high intensity, configured in the form of a MZI have been solved. The input intensities are high enough so that the two-photon induced phase change is larger than the regular gain induced phase change. The model shows that both XOR operation and pseudorandom
binary sequence (PRBS) generation at 250 Gb/s with good signal to noise ratio is feasible. We present all-optical logic NAND gate based on phase-shift keying (PSK)
using SOAs. All simulations are performed under repetition rates of 40 and 100 Gb/s. The device used is SOA-MZI where each arm has a SOA.