基于改进PSO算法设计的TFLN平台偏振不敏感光栅耦合器OA北大核心

Aming at the polarization-dependency issue of grating couplers,standard and improved polarization-insensitive grating couplers are successively designed on the thin film lithium niobate(TFLN)platform.During the design process,the particle swarm optimization(PSO)algorithm is first improved,and then the improved PSO algorithm is used to optimize the grating parameters,including critical parameters such as grating period,duty cycle,etching depth,and incident angle.Finally,a polarization-insensi-tive chirped grating coupler is designed,and the effective refractive index is adjusted through linear chirp,significantly improving the coupling efficiency and polarization-insensitive bandwidth.The simulation results show that the coupling efficiency is the highest at the wavelength of 1 544 nm,and the coupling losses of the transverse electric(TE)and transverse magnetic(TM)modes of the polarization-insensitive chirped grating coupler are-4.88 and-5.05 dB,respectively.The polarization-dependent loss(PDL)is less than 0.5 dB within the wavelength range of 1 500 nm to 1 580 nm,and the polarization-insensitive bandwidth is 45 nm.