Optical Net Extraction

get_optical_nets() extracts connectivity from geometric port adjacency in a layout cell. Two ports that physically overlap at the same position, on the same layer, and facing opposite directions are considered connected.

How it works

1. Bucket cell ports by snapped (x, y) position and layer key
2. Bucket instance ports by their transformed (x, y) position and layer key (array instances are expanded element-by-element)
3. Check candidate pairs in neighboring buckets using check_connection():
4. Cell-to-cell: requires opposite orientation
5. Cell-to-instance: requires same orientation (snapped)
6. Instance-to-instance: requires opposite orientation
7. Pairs passing the bitmask check become Net entries

Bitmask checks

The required check is built from PortCheck flags:

base_check = PortCheck.position + PortCheck.layer + PortCheck.port_type
if not allow_width_mismatch:
    base_check += PortCheck.width

Function signature

def get_optical_nets(
    cell: CellLike,
    port_types: Sequence[str] = ("optical",),
    *,
    allow_width_mismatch: bool = False,
) -> list[Net]:

Parameters

Returns

A list[Net] where each net connects exactly two port members (cell port or instance port) that are geometrically adjacent.

See Also