How to Use your Own Layer Definitions

[yoga545]

Hello every time I create a mask using GDSFactory and exporting it to Klayout I seem to somehow export the custom layer definition from GDSFactory. Is there a way to use default layers (aka layer 1, layer 2, layer 3)?

Any help would be greatly appreciated.

[sebastian-goeldi]

Not sure what you are referring to, but this is just Oasis doing its job. Oasis allows to write layer names. If you want different layernames define your own LayerMap.

[kunal-sr]

What you’re seeing is expected behavior.

GDS files themselves do not store layer names like WG, SLAB150, etc. They only store numeric layer/datatype pairs such as (1, 0), (2, 0), etc.

The reason you see named layers in KLayout is because a layer properties file (.lyp) is being loaded, which maps numeric layers to human-readable names from the active PDK.

So nothing extra is being exported — KLayout is just applying a layer map when displaying the file.

If you want plain numeric layers (1/0, 2/0, 3/0)

You have two options:

Option 1 – Remove the layer properties file in KLayout

In KLayout:

Open View → Layer Properties

Load a blank/default configuration

Or remove the current .lyp file

Then you’ll see raw numeric layers like:

1/0
2/0
3/0

Option 2 – Explicitly use numeric layers in gdsfactory

If you want full control, define layers directly:

import gdsfactory as gf

c = gf.Component()

c.add_polygon(
[(0, 0), (10, 0), (10, 10), (0, 10)],
layer=(1, 0)
)

c.write_gds("simple.gds")

This guarantees only numeric layers are used.

[sebastian-goeldi]

c.show() uses an oas file though. You can see that that's kikely the case, cause the stipples and frames are standard klayout behavior if nothing else is defined.