数字型太赫兹带通滤波器的逆向设计及优化

Reverse design and optimization of digital terahertz bandpass filters

针对高性能太赫兹功能器件的规范化设计需求,本文将智能逆向设计方法应用于太赫兹带通滤波器的设计与优化中.建立与数字空间映射的亚波长超表面等效模型,从设定器件的目标功能和约束条件出发,利用智能算法探索整个解空间中的全部可能结构,迭代寻优至最优结构图案.本文利用搭建的逆向设计框架设计了中心频率为0.51 THz、带宽为41.5 GHz、插入损耗为–0.1071 dB的太赫兹带通滤波器.与传统的人工正向设计相比,逆向设计方法可解构出窄带、低插入损耗、带外抑制强、极化稳定性强的带通滤波器.

In this paper,an ingenious reverse design method is applied to the design and optimization of terahertz bandpass filters in order to achieve standardized design of high-performance terahertz functional devices.An equivalent model of subwavelength metasurface mapped to digital space is established.Based on ideal objective functions and constraints,intelligent algorithms begin a bold journey to explore the vast potential structure in the solution space.Through iterative refinement,the algorithm reveals optimal structural patterns,unlocking areas of unparalleled performance.The direct binary search(DBS)algorithm and the binary particle swarm optimization(BPSO)algorithm are compared in optimization process.When using the DBS algorithm to optimize the design area,it takes a long time to poll the logic states of all pixel units point by point,and it is easy to get stuck in the local optimal value.However,BPSO algorithm has stronger global search capabilities,faster convergence speed,and higher accuracy.Through a comprehensive comparison of the device performance optimized by the two algorithms,the solution optimized by BPSO algorithm has better out-of-band suppression performance and a narrower full width at half peak,but slightly lower transmittance at the center frequency.The bandpass filter has a center frequency of 0.51 THz,a bandwidth of 41.5 GHz,and an insertion loss of-0.1071 dB.When considering computational efficiency,DBS algorithm lags behind,the simulation time is 11550 s,while BPSO algorithm only needs 9750 s.Compared with the traditional forward design,the reverse design method can achieve the narrower band,lower insertion loss,better out-of-band suppression and polarization stability.The fine structural changes of the optimal results have a significant influence on spectral performance,demonstrating the superiority and uniqueness of reverse design.This technology contributes to the design and optimization of high-performance and novel functional devices.