Research On All-optical Logic Gate Based On QD-SOA-MZI

The quantum dot semiconductor optical amplifier(SOA-QD)has the advantages of high gain,high saturated output power and low noise figure,as well as low temperature sensitivity.Therefore,it can meet the requirements of high-speed all-optical networks for device response speed and transmission quality.The Mach-Zehnder interferometer(MZI)is implemented by QD-SOA.It can overcome the influence of the feedback light wave on the light source during signal transmission.It also has the characteristics of high output signal-to-noise ratio and high extinction ratio.Many all-optical logic gates can be realized by QD-SOA-MZI's all-optical wavelength conversion.The turbo-switch structure at the output port of the all-optical logic gate can improve the output characteristics of the logic gate.In this structure,the filter is cascaded with QD-SOA,which can improve the QD-SOA gain recovery time while optimizing the output characteristics of the logic gate.Using the QD-SOA-MZI structure,the all-optical NOR gates and XNOR gates is designed.And using the turbo-switch structure to design the NOR gate and XOR gate based on QD-SOA turbo-switch MZI(QD-SOA-TSMZI).The main content of the paper is as follows:1.The principle of all-optical wavelength conversion and the working principle based on all-optical logic gates are introduced.According to the transition rate equation and the light field transmission equation,the segmented model,static model and dynamic model are described.2.The all-optical logic NOR gate is implemented by QD-SOA-MZI,and the simulation structure diagram and working principle are introduced.By simulating parameters such as the maximum mode gain,pulse width and the length of active area as well as noise of the NOR gate,the Q factor characteristics and extinction ratio characteristics of the NOR gate are analyzed.The influencing factors of the simulation results are analyzed,and the value ranges of the parameters of high Q factor and high extinction ratio are obtained.3.A QD-SOA-MZI cascade structure is proposed.Two Mach-Zehnder interferometers are cascaded,and the all-optical logic XNOR gate is designed.The simulation structure diagram and working principle are introduced.By simulating the active area width of the XNOR gate,input signal wavelength and loss factor as well as maximum mode gain and other parameters,the Q factor characteristics and chirp characteristics of the XNOR gate are studied.The reasons for the influencing factors of the simulation results are analyzed.The simulation results can be used to optimize the output performance of the XNOR gate.4.The working principles of turbo-switch structure and turbo-switch MZI structure are introduced.And QD-SOA and turbo-switch MZI structure are combined together.Based on QD-SOA-TSMZI,all-optical logic NOR gate is simulated and analyzed.Compared with QD-SOA-MZI all-optical logic NOR gate,their simulation results are analyzed.The effects of the maximum mode gain,pulse width,the length active region,and line width enhancement factor as well as other factors of the two NOR gates on the Q factor and extinction ratio are studied.The results indicate that the output characteristics of the QD-SOA-TSMZI all-optical logic NOR gate are better.At the same time,the all-optical logic XOR gate based on QD-SOA-TSMZI is realized by the turbo-switch MZI structure.The influences of the length of the active region,the electronic transition time from the excited state to the ground state,the electronic transition time from the wetting layer to the excited state,and the detection optical power on the XOR gate Q factor,pattern effect and conversion efficiency are analyzed.The reasons for the simulation results are analyzed.The optimization of the output performance of the XOR gate can be realized by adjusting the simulation parameters.