Design And Research Of All-optical Logic Devices Based On 2-D Photonic Crystal

The all-optical half-adder is an important unit for the realization of photonic integration and photon calculation.In this paper,the all-optical half-adder is designed by using the photonic band gap and photonic localization of photonic crystal.Based on the proposed reconfigurable AND and NOR logic gate structure and reconfigurable XOR logic gate and half-adder structure,a photonic crystal half-adder with loss compensation is designed.It has the characteristics of high contrast ratios,short response time,large working bandwidth and flexible size,which also make the designed structure have superior implantability and matchability in optical integrated circuits.This article focuses on the following aspects:(1)Based on the coupling theory of photonic crystal waveguide and resonant cavity,a twodimensional photonic crystal waveguide beam splitter is designed in this paper.And compared the designed beam splitter with the photonic crystal Y beam splitter in terms of anti-interference ability.Through research,it is found that the photonic crystal beam splitter based on coupling theory has stronger anti-interference ability and higher transmission efficiency.By studying the radius of the defect column R1 in the structure,the coupling efficiency of the resonant cavity is improved,and the transmission efficiency of the beam splitter reaches 100%.(2)Based on the principle of light interference,two structures of reconfigurable logic gates are designs in this paper.The structure of reconfigurable AND and NOR logic gates can be restructured to have AND or NOR logic function by controlling the electromagnetic wave incident on the controlsignal-port.The contrast ratio of the reconstructed AND logic gate is 6.33 d B,and the response time is 0.2ps.The contrast ratio of the reconstructed NOR logic gate is 8.75 d B,and the response time is0.13 ps.The structure of reconfigurable XOR logic gate and half-adders can be restructured to have XOR or addition logic function by redefining the control signal port.The contrast ratio of the reconstructed XOR logic gate is 5.84 d B,and the response time is 0.2ps.The contrast ratios of the reconstructed half-adder are 4.42 d B and 12.3d B,and the response time is 0.3ps.(3)Based on the designed photonic crystal beam splitter and reconfigurable logic gates,a new half-adder structure is proposed.The contrast ratios are calculated to be 4.67 d B and 10.77 d B,and the response time is 1ps.Through the analysis of the electromagnetic wave loss in the structure,the structure of the half-adder is optimized,and a photonic crystal half-adder structure with loss compensation is proposed.The contrast ratios are calculated to be 8.26 d B and 15.34 d B,and the response time is 0.47 ps.(4)In this paper,the linear relationship between the working-wavelength of the half-adder and the size of the structure is studied.Through theoretical analysis,it is found that scaling the size of the photonic crystal does not change the normalized frequency of the photonic crystal.The study found that,by considering the dispersion relationship between the working-wavelength and the refractive index of the material,the device can still work normally after the size of the photonic crystal device and the working-wavelength are proportionally scaled by 0.72-1.66 times.