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A bi-directional optical propagation tool

Fibre to Chip End Facet Coupling

Simulations with FIMMPROP software

When trying to optimise and characterise the transmission from an optical fibre to the end facet of an optical chip, a large number of parameters can be optimised.

Our 3D bi-directional propagation tool FIMMPROP allows you to model with great efficiency and accuracy the influence of various effects such as:

  • fiber-to-chip mode size matching (spot size matching),

  • fiber-to-chip mode index matching,

  • optimisation of the waveguide / fiber geometry and dimensions,

  • fiber-to-chip alignment,

  • existence and length of a free-space gap in between the fibre and the chip,

  • tapering of the waveguide (spot-size converter),

  • thin-film filters, anti-reflection coatings,

  • fiber lensing.

Note that FIMMPROP can also model other types of fiber to chip couplers, including surface-emitting gratings, and various mode size converters (or spot size converters) such as grating-assisted mode size converters and inverted tapers.

Unlike a BPM, FDTD or FEM tool, FIMMPROP is able to generate fast optimisation of such structures, thanks to its fast scanning capability which only needs to re-calculate the parts of the simulation that have changed.

In the example below we are optimising fiber-to-chip vertical alignment for a butt coupled structure with a 100nm air gap.

Optimising vertical alignment

Scanning vertical alignment between a waveguide and a fiber
separated by a 100nm free-space gap