Studies On Key Technologies Of Optical Signal Processings In Advanced Optical Networks

With the development of Internet & multimedia technology, the optical networks face greater challenges in processing much higher speed and greater data capacity. Advanced optical signal processing technology is expected to release the network from undesirable latencies related to O/E/O conversions at the switching nodes, and enhances the capability of the optical networks.This dissertation aims to tackle several key technologies of optical signal processing in advanced optical networks, and the main content is about the signal processing technologies based on the nonlinearity of semiconductor optical amplifier (SOA) and quantum-dot SOA (QD-SOA), such as data format conversion, optical time division demultiplexing and optical frequency conversion.The research status of optical signal processing technologies in advanced optical networks are analyzed in Chapter 1, including the optical logic gates, optical wavelength converter and optical time devision demultiplexing. And then the operational principles and the system performance of optical signal processing schemes utilizing SOA are remarked on. In Chapter 2, the structure, the operational principle and the unique properties of QD-SOA are illustrated, and the three-level rate equation model of QD-SOA is introduced.In Chapter 3, ultra-fast optical format conversion from nonreturn-to-zero (NRZ) to return-to-zero (RZ) is proposed utilizing QD-SOA assisted Mach-Zehnder interferometer (QDSOA-MZI). Through numerical simulations, this scheme operating at 160Gbit/s is validated and its performance is studied. Consequently, several rules and limits on the parameter design have been drawn.Ultra-fast optical time division demultiplexer using QD-SOA are proposed in Chapter 4, and through numerical simulations, this scheme is validated for 320Gbit/s and 160Gbit/s demultiplexing operation. In searching of the optimal parameters and the suitable operation condition, the demultiplexer performance is investigated in terms of contrast ratio and Q-factor. At last, several rules and limits on the parameter design are drawn. A novel scheme of optical frequency conversion based on two-pump four-wave mixing (FWM) effect in SOA is proposed in Chapter 5. The system performance is analyzed through a numerical model, and the impact of the bias current, the pump power and the pump frequency space on the conversion efficiency is discussed. The results show that this scheme can be applied for the frequency conversion of optical radio signal in Radio on fiber (RoF) systems.