Investigation On All-Optical Buffer Based On SOA

With the rapid development of communication technology, higher switch capacity and switch rate of the key nodes is needed. However, the switch of the communication network still performs in the electrical domain currently. The "optical-electrical-optical" conversion mode limits the switch capacity and switch rate, which can be solved by all-optical network fundamentally. Therefore, all-optical packet switching technology is one of the best ways to improve the performance of swtich nodes of the network, in which all-optical buffer is the most important component to determine the development of optical network. All-optical buffer based on quantum dot SOA and Gain transparent SOA are analyzed in this paper.In this paper, the basic theory of quantum dot SOA and the dynamic model are analyzed. The basic theory includes the structure of quantum dot SOA, operating principle, the rate equation of carrier concentration, the relationship between gain and phase shift. Based on these basic theories, the simulation approach of quantum dot SOA is detailed describe in this paper. The simulation model of optical pulses transmission in a quantum dot SOA is established. The theoretical calculation of pattern shape of single pulse and continuous pulse signals after being buffered in DLOB is carried out. It is demonstrated that quantum dot SOA is suitable for fiber all-optical buffer and pattern effect will be significantly improved theoretically. The correlation between injected electric current, control light power and the phase shift of bulk-SOA and quantum dot SOA is analyzed. Compared with bulk-SOA, quantum dot SOA can obtain the same phase shift with low injected electric current. And the larger the linewidth enhancement factor of quantum dot SOA is, the less the control light power of the DLOB system is needed.All-optical buffer based on cross polarization modulation and cross phase modulation in gain transparent SOA is introduced. The basic theory of gain transparent SOA is elaborated. It is demonstrated that the carriers’ change process after the injection of current and signal light and the phase shift which is caused by the "optical-optical" interaction between assist light and signal light. In this paper, utilizing cross phase modulation effect in gain transparent SOA to control the phase of signal, a new format conversion system based on gain transparent SOA is proposed. OOK-8PSK format conversion is realized by utilizing three cascaded gain transparent SOA to modulate phase. Cross-gain modulation and four-wave mixing can be avoided because of the characteristics of gain transparent SOA. The8PSK format signal is judgment and feasibility of this system is proved by precisely demodulating OOK signal from8PSK signal.