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A WDM/DWDM model for AWGs and Echelle Gratings

Modelling tapering and cross-talk
in I/O waveguide arrays


The effect of tapering in the input and output waveguides in echelle gratings can be modelled using Epipprop combined with FIMMPROP. This will allow you to characterise the amount of unwanted cross-talk introduced by cross-coupling between neighbouring waveguides, and the associated deterioration in performance for the echelle grating.

Spectra obtained with and without modelling the cross-coupling in the case of a non-optimum waveguide array can be found below. You can see that the cross-coupling introduces a fairly high level of cross-talk in the output spectrum as the transmission peak becomes wider when the cross-coupling in the taper is introduced (see arrow).

Impact of the waveguide cross-coupling on performance (left) output spectra without taper model
(right) output spectra with taper model; notice the widening of the peak pointed by the arrow

The corresponding Epipprop/FIMMPROP simulation showing the cross-coupling in the input waveguide array is shown below.

Tapering and cross-coupling in I/O waveguide arrays
(top-left) XZ intensity profile in a tapered waveguide array showing unwanted cross-coupling towards the end
(bottom-right) XY cross-section of the resulting Ex field launched in the slab of the grating,
showing light coupled to the adjacent waveguides