Author: Mayank Bahl and Robert Scarmozzino
Thursday, March 1, 2018
Synopsys Inc., Optical Solutions GroupThe Effective Index Method (EIM) can be used in Synopsys RSoft™ photonic design software to greatly reduce the computation time and memory requirements of a simulation by converting a 3D structure into an approximate 2D structure. This is also called an approximate 2.5D structure. Once a 3D structure has been reduced into a 2.5D structure using EIM, the propagation can be performed using one of numerous algorithms suitable for computational photonics, such as Finite Difference Time Domain (FDTD), Beam Propagation Method (BPM), Eigenmode Expansion (EME) and Rigorous Coupled Wave Analysis (RCWA). Most of the RSoft passive device modeling tools, including BeamPROP™, FullWAVE™, ModePROP™ and DiffractMOD™, all support EIM.
This white paper illustrates the performance and accuracy benefits of the EIM approach for two SOI-based structures: a ring resonator example and a 1x2 MMI example. Moreover, by applying three different numerical techniques and software tools available for modeling such devices in the RSoft photonic design toolset, and comparing their results and computational requirements, the white paper demonstrates that the right choice of the numerical technique can lead to substantial savings in computational time and shorter design cycles through rapid prototyping. This is extremely significant, since one of the biggest challenges in designing today’s photonic systems is meeting computational resource requirements to perform the simulation, where in practice, a simulation can take hours, days or even weeks.