Research Of All-optical Logic Devices Based On Nonlinear Effect

With the development of social material civilization and people's demand for Capacity of communication and the transmission speed of information becomes higher.In order to effectively solve the problem of "electronic bottleneck" in optical physics,an important task in optical physics is to develop all optical switching devices.All optical switch is the key component in all optical communication system and optical computing,and it can realize many kinds of logic functions in all optical field.In the process,there is no light / electricity / light conversion,so the transmission efficiency and transmission speed are greatly improved.In addition,all optical logic devices based on nonlinear effects have gradually become a research focus in the field of optical communication.In this paper,we focus on two kinds of typical all-optical logic devices,which are all optical logic gates and all-optical packet switching.The main work and main research results are as follows:Firstly,this paper briefly introduces the basic structure,working principle and coupled mode theory,and the switching characteristics of the coupler are simulated by the coupled mode equations.Then the structure of the fiber grating is described,and the coupling mode theory of the active fiber grating is analyzed.At the same time,this article briefly introduces the working principle of micro ring resonator.Based on the coupled mode equations,the operating principle of single coupler,double coupler and cascade coupled micro ring resonator are discussed.By using the coupled mode equation,the transmission characteristics of the cascaded micro ring resonator are analyzed and calculated.Secondly,we design a kind of all optical logic gates based on phase shifted grating,and discuss its switching characteristics.In the study,the fiber grating is used to form a nonlinear phase shift fiber grating,because the photon is not charged,it can not be used to control the intensity or propagation direction of the other beam with a beam of light.Therefore,based on the nonlinear optical case,according to the cross phase modulation,the laser(pump)will cause the change of medium parameters and change a bundle of optical signal intensity or direction,so as to control the output switching weak continuous wave,and then realize the light information from the pump to continuous light.By changing the two pump combination,we calculate the extinction ratio according to the output power.Then using the extinction ratio to determine implementation of logic function,when the phase shift of phase shifted grating is zero,we realized the gate and NAND gate.when the phase shift of phase shifted grating is ?,we can achieve a NAND gate and gate.Finally,we draw the conclusion: when we choose different phase shift of the phase shifted grating phase,we can construct different logic gates by calculating the transmittance and reflectance,theextinction ratio curve.The threshold power of optical switch can be reduced effectively by using the different shifted phase of the phase-shifted fiber grating,which can be more applicable to the practical optical communication network.Thus,this optical communication network can be more suitable to the practical application.Finally,an all optical packet switching based on cascaded micro ring resonators is designed.By using the numerical method and analytical method,the bistable characteristics of the cascaded micro ring resonators are calculated and analyzed.First,modulate a set of pseudo random sequence to the bias signal,by using a set signal and reset signal,the data signal is adjusted to get different output power at the two output ports.We realize the interaction of the data signal output at two ports,finally we achieve the data packet switching function.It is found that the pulse width of the set of signal and reset signal must be larger than the field setup time of the cascaded micro ring resonator.In the process,we take this time length as 2.16 ps.In addition,the paper also found that:compared with the single microring resonator,cascaded microring resonator can effectively reduce the bias power,thus it is more suitable for the practical application.In addition,by increasing the number of cascaded micro ring resonators,we can realize the multi routing packet switching.