Topology Optimal Design of NRD Guide Devices Using Function Expansion Method and Evolutionary Approaches

Abstract

In order to increase communication capacity, the use of millimeter-wave and terahertz-wave bands are being actively explored. Non-radiative dielectric waveguide known as NRD guide is one of promising platform of millimeter-wave integrated circuits thanks to its nonradiative and low loss nature. In order to develop millimeter wave circuits with various functions, various circuit components have to be efficiently designed to meet requirements from application side. In this paper, for efficient design of NRD guide devices, we develop a topology optimal design technique based on function-expansion-method which can express arbitrary structure with arbitrary geometric topology. In the present approach, recently developed two-dimensional full-vectorial finite element method (2D-FVFEM) for NRD guide devices is employed to improve computational efficiency and several evolutionary approaches, which do not require appropriate initial structure depending on a given design problem, are used to optimize design variables, thus, NRD guide devices having desired functions are efficiently obtained without requiring designer's special knowledge.

Function expansion based topology optimization of NRD guide device using hybrid method of harmony search and gradient method

“…In recent years, optimization technique utilizing computer simulation has attracted a lot of attention to develop high performance electromagnetic devices [11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]. Among such optimization techniques, topology optimization method has the highest design freedom and has potential to develop innovative devices beyond human knowledge.…”

“…However, when we apply this gradient based topology optimization method to NRD guide [14], an appropriate initial solution is often required to find global optimal solution due to multimodal nature of an objective function compared with design of photonic devices [26]. On the other hand, when we employ evolutionary algorithm, which is multi-point search method such as genetic algorithm (GA), differential evolution (DE), hybrid firefly algorithm (HFA), harmony search (HS), and so on, global optimal solution may be found out, however computational cost is usually high [18,28,30].…”

“…Therefore, to overcome such problem, we propose hybrid optimization scheme of HS and GM. To show the validity of this hybrid optimization approach, NRD guide bend and frequency demultiplexer are designed and the design efficiency is compared with those of conventional evolutionary approaches [30]. The proposed hybrid scheme is not limited to HS and other evolutionary methods can be hybridized with GM to improve optimization efficiency.…”

Analysis of NRD guide devices using rigorous two‐dimensional full‐vectorial FDTD method

“…The 2D-FVFEM has been successfully utilized for several optimal design of NRD guide devices including dielectric and magnetic materials. [19][20][21][22][23][24][25] On the other hand, the time-domain simulation method is useful for analyzing broadband device properties. The 2D-FVFEM can be extended into a time domain analysis two-dimensional full vectorial finite element time domain (2D-FV-FETD) method, but it could be more challenging as compared to 2D-FVFDTD.…”

“…Recently, we have developed two‐dimensional full vectorial finite element method (2D‐FVFEM), 18 which can efficiently analyze NRD guide devices without sacrificing numerical accuracy. The 2D‐FVFEM has been successfully utilized for several optimal design of NRD guide devices including dielectric and magnetic materials 19–25 . On the other hand, the time‐domain simulation method is useful for analyzing broadband device properties.…”