Dynamic Simulation Model Of The Qd-soa And Its Applications In Optical Signal Processing,

In the development of optical network, the limit of the O/E (E/O) conversion in the switching nodes has been the bottleneck of further improving the bandwidth of the network. Optical packet switching (OPS) can solve this problem. All-optical signal processing is one important part of the researches on OPS. Comparing to bulk Semiconductor Optical Amplifier (SOA) and Quantum-well Semiconductor Optical Amplifier (QW-SOA), Quantum dot Semiconductor Optical Amplifier(QD-SOA) have many unique advantages, such as lower threshold current, lower temperature sensitivity, lower linewidth enhancement factor, high differential gain, high modulation bandwith and faster gain recovery. Owing to so many advantages, QD-SOA is much more adapted to be used in the all-optical signal technology. The amplifying characteristics of QD-SOA, the numerical fragment model of QD-SOA and it's applications in the all-optical signal processing related to OPS are investigated in this dissertation. The main research works are listed as follows:1. Based on the rate equations of the electron transition and the traveling-wave equation for signal wave in the QD-SOA, the numerical fragment model of QD-SOA is established. The Newton method is adopted to search the initial values of the model and the 4th order Runge-Kutta method is used to calculate the dynamic variation.2. The research activities involve the influences from the device-related parameters: the maximum modal gain, the length of the active layer, the transition time between the excited-state and ground-state. The characteristics of output pulse signal including extinction ratio, pulse width and gain have been chosen to the observing and comparing objects. The analysis in theory has also been provided to explain the simulation results.3. The study of wavelength conversion based on QD-SOA's cross gain modulation (XGM) focus on the relationships between the extinction ratios, the converted pulse width and the length of active region, the input signal power, the electron transition time. The results show that the extinction ratio can be improved by increasing the length of active region, the input signal power or the electron transition time, but companying with the increase of output pulse width.4. A novel scheme of all-optical NOR gate based on the gain properties of QD-SOA is proposed.The feasibility of the scheme is investigated by simulation. No pattern effects is observed at the outputs of the NOR gate. The extinction of the output signal are higher than 11 dB and the processing rate reaches 400Gb/s.