Adding the bilayer grating coupler notebook

[tomflexcompute]

Adding the bilayer grating coupler notebook

[github-actions]

Spell Check Report

BilayerSiNSiGC.ipynb:

Cell 1, Line 3: 'high-contrast'
  > Silicon nitride has attracted increasing interest due to its superior passive properties. However, similar to silicon PICs, fiber-to-chip coupling remains a significant challenge for SiN platforms. Conventional SiN grating couplers exhibit low coupling efficiency due to their low refractive index contrast. To address this, a high-contrast grating reflector (GR) is employed as a bottom reflector to enhance coupling efficiency, rather than using distributed Bragg reflectors (DBR) or metal reflectors. Through design optimization, combining parameter sweeps and adjoint-based inverse design, a grating coupler with high coupling efficiency (< 1 dB) is achieved.
Cell 1, Line 8: 'Interlayer'
  > 3.  **Interlayer Distance Optimization**: Tuning the distance between the SiN and Si layers.
Cell 1, Line 9: 'apodize'
  > 4.  **Inverse Design**: Using adjoint optimization to apodize the grating for maximum efficiency.
Cell 29, Line 1: 'Interlayer'
  > ## Interlayer Distance Optimization
Cell 30, Line 2: 'z-position'
  > """
Cell 30, Line 18: 'z-position'
  > # Create the Si grating structure using optimal width, period, and the given z-position
Cell 33, Line 1: 'interlayer'
  > Now we perform parameter sweep of the interlayer distance to maximize the coupling efficiency.

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Checked 1 notebook(s). Found spelling errors in 1 file(s).
Generated by GitHub Action run: https://github.com/flexcompute/tidy3d-notebooks/actions/runs/20067654259

[FilipeFcp]

Very nice as always Tom.

Just two typos:

cell [24]: min_featire → min_feature
Label of last figure: "Adjoint ptimized" → "Adjoint optimized"

At first glance I thought that some simple SciPy minimization function could replace the sweep and reach the same result with fewer simulations. However, it would run in series, and the total time would be too long.

[alec-flexcompute]

Great job as always @tom! A couple things:

1. "Combining the optimized SiN grating and the optimized Si reflector." -> "Here we combine the optimized SiN grating and the optimized Si reflector."

2. in cell 24, change "min_featire" to "min_feature"

3. In cell 28, "label="Adjoint ptimized"" -> "label="Adjoint Optiimized""

Other than that, I have no criticisms/suggestions - very clean and clear!