Research On All-Optical Logic Gate Based On Two-Dimensional Photonic Crystal Resonator And Microcavity

All-optical networks are provided with incomparable and huge advantages over traditional electronic technologies,and all-optical logic gates,as one of the most important components of ultra-fast information processing and all-optical computing systems,which has attracted much attention naturally.Photonic crystal is an artificial periodic dielectric structure,which has received a lot of attention from researchers both at home and abroad because it is provided with unique properties such as photonic confinement band and photonic localization.Among them,the multimode interference effect,third-order nonlinear effect,self-collimation effect and resonance properties of cavities of photonic crystals are used to realize all-optical logic gates of photonic crystals,and most of these schemes face the problems of relatively complex device schemes and relatively high power consumption It is realized by making waveguides in photonic crystals and using the linear interference effect of light which is an implementation scheme with simple structure and low power consumption.However,since the optical range difference of the beam arriving at the convergence point during propagation cannot be continuously changed,it is difficult to precisely control the optical range difference to control the degree of phase extinction interference or phase length interference of the light wave,which makes it very difficult to achieve them with high extinction ratio.For the advantages and disadvantages of each method photonic crystal all-optical logic gate with high extinction ratio,small size,simple structure and low power consumption are designed in this thesis by combining the photonic crystal resonant cavity,microcavity and linear interference principle.The main research content and results of this thesis have been listed as follows:(1)In order to minimize the energy loss of the all-optical logic gate,nonlinear materials were not chosen in the experimental scheme of this thesis.Instead,the linear interference effect of light waves was used to design a high-performance all-optical logic gate structure based on the resonant cavities and microcavities of two-dimensional photonic crystals.The plane wave expansion method had been used to analyze the band gap characteristics of two-dimensional photonic crystal orthorhombic lattices as well as triangular lattices.By changing the shape of the ring resonant cavity and the radius of the microcavity,its position and the length of the incident waveguide,the optical range difference of the incident light at the convergence point was changed,and the structural scheme of AND,OR and NOT logic gates was designed,and the structural scheme of XOR,XNOR,NAND,NOR,three-input AND and three-input OR logic gates was designed by cascading and improving the AND,OR and NOT logic gates by the above method.(2)The time-domain finite-difference method was used to simulate and numerically analyzed the designed logic gate.The transmittance of light waves in the device and the extinction ratio and response time of the logic gate were calculated,and the high and low level thresholds were defined,where the output power at the output was defined as high level if it was higher than 0.5 times of the input power,and the opposite was defined as low level.The propagation of light waves in the device was simulated,the field distribution during the operation of the logic gate was obtained,the truth table corresponding to the logical relationship of each logic gate was listed one by one,and the logic function of the proposed logic gate was then proved.(3)The most basic logic performance requirements of the designed logic gates were not only satisfied but also had the advantages of small design structure size,high extinction ratio,fast transmission rate,high efficiency,short response time where the extinction ratio was above 3.1d B and the maximum could reach 15.2d B,and the response time was within 1.8ps and the shortest could reach 0.35 ps,which laid the foundation for the future design and manufacture of all-optical logic devices and had a profound impact on the development of all-optical networks.