Comprehensive waveguide design environment for the analysis and optimization of planar integrated optical waveguides, components and fibers

MODE Solutions’ variational FDTD (varFDTD) solver can efficiently simulate the propagation of optical fields in time without making any assumptions about an optical axis or the materials used. The built-in frequency domain monitors automatically perform the necessary calculations to return the continuous-wave results.
This propagation capability is based on an FDTD technique customized for omni-directional propagation within waveguide components. This method employs a highly optimized computational engine, as well as advanced meshing routines.  The combination of this propagation capability and the eigenmode solver technology provides engineers with the ideal environment for virtual prototyping of large-scale high index contrast waveguide components, reducing the need for expensive, time-consuming manufactured prototypes.

Eigenmode expansion (EME) solver

Figure 2:(Right) The transmission as a function of taper length for the spot-size converter in [1] (also pictured on the left side) calculated using the EME solver and 3D FDTD. The EME simulation takes about 1 minute to simulate 101 different taper lengths (blue squares), whereas the same device simulated in 3D FDTD takes about 6 hours for 11 different taper lengths (green squares).

The EME method is a fully vectorial and bi-directional technique to solve Maxwell's equations. The methodology relies on the modal decomposition of electromagnetic fields into a basis set of eigenmodes, which are computed by dividing the geometry into multiple cells and then solving for the modes at the center of each cell.  Scattering matrices for each cell are formulated by applying boundary conditions at the interface between each cell. The solution to each cell is then propagated bi-directionally to calculate the total transmission and reflection of the device, as well as the final field profile. The EME method has several advantages over other propagation methods:
  • Beam propagation methods (BPM): unlike BPM, which relies on a slowly varying envelope approximation, the EME method makes no such approximations and is a rigorous technique. The accuracy of BPM also becomes compromised for propagation at large angles, or in components with high refractive-index contrast, making it unsuitable for photonic components manufactured from silicon or other high index contrast material systems.
  • Finite-difference time-domain (FDTD) methods: the EME method scales exceptionally well with propagation distance and is an ideal method for simulating long structures whereas FDTD-based methods, while rigorous, exhibit significant increases in simulation times as the length of the device increases.
  • Please contact:crackcad@gmail.com

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