HangerResonator breaks WaveguideComposite

[iqmtestd]

WaveguideComposite does not always work with embedded HangerResonator. We'd expect this to always work.

WaveguideComposite Nodes may specify simple Elements to be embedded in the waveguide. This does not work well with HangerResonator. Often it breaks with a ERROR: IndexError: list index out of range in PCellDeclaration.produce message.

Other times it does succeed but even then the guiding lines may be wrong:

The macro to create the above example:

from kqcircuits.klayout_view import KLayoutView
from kqcircuits.elements.waveguide_composite import Node, WaveguideComposite
from kqcircuits.elements.hanger_resonator import HangerResonator

view = KLayoutView()

nodes = [
    Node(pya.DPoint(0, 0)),
    Node(pya.DPoint(500, 0)),
    Node(pya.DPoint(500, -300)),
    Node(pya.DPoint(200, -300), face_id="2b1"),
    Node(pya.DPoint(0, -300)),
    Node(pya.DPoint(-200, -300)),
    Node(pya.DPoint(-200, -600), face_id="1t1"),
    Node(pya.DPoint(-200, -1000)),
    Node(pya.DPoint(-200,-1600), HangerResonator),
    Node(pya.DPoint(-500, -1000)),
]
view.insert_cell(WaveguideComposite, nodes=nodes)

view.focus()

Similarly, when trying to use port_pl_a and port_pl_b, like this:

    Node(pya.DPoint(-200, -1600), HangerResonator, align=('port_pl_b', 'port_pl_a')),
    Node(pya.DPoint(-500, -2000)),

it does not always produce the expected shape:

Versions

KQCircuits: v4.7.0
KLayout: 0.28.12
Python: 3.10.12
OS: Ubuntu 22.04.3

Issue Severity

Medium: significant difficulty but I can work around it

[iqmtestd]

We don't know why this happens. A possible reason is that HangerResonator uses WaveguideComposite and the recursive nature of this usage may confuse KLayout. Or we just have some logic error in WaveguideComposite that has not been discovered yet.

[Qvadi]

Awesome! Tested and works.