Design Of Micro-Nano Optical Devices Based On The Method Of Moving Asymptotes

Micro-nano photonics devices are important components for building all-optical networks.They are widely used in optical communication,optical computing,visual optics,quantum optics,due to their small size,low power consumption,and high integration.With the advancement and development of science and technology,the optical devices designed by traditional design methods have been difficult to meet the current integration requirements due to single function,too large size,and low performance.In order to break through the difficulties encountered by traditional optical design methods,intelligent methods that combine structural optimization algorithms with numerical calculation methods are widely used in optical design.In this paper,the intelligent design method combining the moving asymptote algorithm and the finite element method is used to design micro-nano optical devices such as large-angle optical power beam splitters,optical polarization beam splitters,all-optical logic devices,and optical wavelength division multiplexers.The main work of the paper is as follows:A large-angle silicon/air optical power beam splitter with a size of only 1μm×2μm is designed by using an intelligent design method.It can split TE light from950nm to 1600nm into 180 degrees with a split ratio of 50:50.At the wavelengths of1310nm and 1550nm,the total efficiency of the device is 94.6%and 93.1%,respectively,and the average transmittance over the entire wavelength range also exceeds 91%.At the same time,we also switched to Ga N/air and SiO₂/air materials for device design,and obtained good results in different wavelength bands.A set of polarizing beam splitters with a size of 2μm×2μm was designed by intelligent design method.The polarizing beam splitter has a bandwidth of 800nm to1600nm,with a maximum transmittance of 93%for TE and 73%for TM.Meanwhile,in the wavelength range from 800nm to 1600nm,the average extinction ratio of TE is 18.9B;the average extinction ratio of TM is 19.6dB.The extinction ratio of the device is relatively large,while the insertion loss is small.In order to prove the good applicability of our design method,other polarizing beam splitters with different material substrates and different output directions are designed.Combined with the polarization beam splitter,a number of nanoscale all-optical logic devices are designed to realize logic operations such as"AND","OR","NAND"and"NOR"gates.A three-channel wavelength division multiplexer with a size of 2μm×2.4μm is designed by using the intelligent design method,which can realize the output of optical signals with wavelengths of 800nm,1000nm and 1200nm at different ports,and the transmission efficiency is 84%,79%and 72%,respectively.We also designed 800nm and 900nm two-channel wavelength division multiplexers with smaller wavelength intervals,and their transmission efficiencies were 65%and 63%,respectively.