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The design of the spot-size converter is based on reference [1]. The goal of this design is to efficiently couple light from a strongly confined high index contrast silicon waveguide into an optical fiber, which has a much larger mode field size. In this design, the spot-size conversion is achieved by using an Si adiabatic taper covered by a low-index waveguide. Once the mode is converted from the silicon waveguide to that of the larger low-index waveguide, it can be coupled much more efficiently into the optical fiber.


The EME method is ideal for taper designs because one can sweep the taper lengths quickly without having to calculate any additional modes. In this case, FDTD-based methods are not as efficient because not only does the simulation time increase with taper length exponentially but also separate simulations are required for each taper length.




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Discussion and results

Modeling instructions

See also

EME Solver Analysis


[1] T. Tsuchizawa et al, “Microphotonics devices based on silicon microfabrication technology”, IEEE J. Select. Topics Quantum Electron., 11, 2005, 232-240



Learning objectives

In this example, we show how MODE' eigenmode expansion (EME) solver can be used to design a spot size converter. The user will learn to:

Set up an EME simulation

Quickly scan the length of the spot size converter to find the optimal design

Compare results with 3D FDTD results


Spot size converter Getting Started video

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