New edge coupler for SiN

[jryckma]

Added an experimental SiN gds of the Clemson edge coupler which includes an angled facet. For H = 400 nm SiN at 1310 nm.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.15%. Comparing base (f62fc83) to head (70c61a2).
⚠️ Report is 6 commits behind head on master.

Additional details and impacted files

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  Coverage   73.15%   73.15%           
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  Files         106      106           
  Lines       12941    12941           
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  Hits         9467     9467           
  Misses       3474     3474           

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[lukasc-ubc]

We should probably have two variants of this cell. The one here is for the Shuksan process with two deep etches. The regular ANT process has one deep etch, and this cell should work well in that process as well. I made Shuksan-specific cells with an addition of "Shuksan" in the cell name. In your case, it could be SiN_Shuksan_EdgeCoupler_Clemson_te1310_Angled.gds

Did you consider substrate leakage in your simulations? For a large mode that overlaps well with SMF, I worry that it will leak down.

Thank you
Lukas

[jryckma]

Sounds good thanks. We can make a regular ANT (non-Shuksan) version with the trench on layer 201 instead of 203. Yes there is about 5 dB/cm of leakage in the sim due to the handle. It could get worse depending on the exact oxide refractive indices, but it seems to be manageable (<0.25dB total) for such a short taper (0.05 cm).

I think we could make a straight version of it as well that could support cutback measurements if desired (although it is kind of big).

Thanks,
Judson