waveguide_composite with other non-standard elements

[Qvadi]

Hi,
The waveguide_composite element is a really useful building tool for complicated structures. I have a question regarding using this element:
When building the nodes, sometimes, you may want to place another element between the nodes, for eg, a two-port hanger resonator whose probe line is part of the element structure. I have ref_ports assigned to the probeline of the hanger_resonator, and when I try to insert this hanger resonator in the Node definition when building the waveguide_composite, it fails. I also tried to align it using the ports but doesnt work.
Is there a simpler solution to achieve this?

Eg code, I was playing with after including the relevant imports:

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(0, -1000)),
Node(pya.DPoint(600, -1000), HangerResonator, align=('port_pl_a', 'port_pl_b')),
]

[qpavsmi]

Hi, thanks for sticking with KQCircuits :)

To start with, could you report the stacktrace that gets printed after the failure? It should show up in KLayout either where the PCell is supposed to be or from top toolbar: File > Log Viewer. Example of the failure stacktrace:

It would also help us if you could share your code of the hanger_resonator, but if you don't want to share it, we will try to help as best as we can without it

[qpavsmi]

Show me please what it shows when it fails.

And also sharing your HangerResonator code would help, unless you're using our implementation of hanger resonator?

[qpavsmi]

Ah I see that you are using our implementation of hanger resonator :D

Will look into what this needs for this to work, or if there is a bug that we need to fix

[Qvadi]

Yes, I am using the default HangerResonator code.

My node list is:

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(0, -1000)),
Node(pya.DPoint(600, -1000)),
Node(pya.DPoint(800,-100), HangerResonator)
]

[Qvadi]

I think what would be really nice is an example to show how I can drop elements into the Node definition of a waveguide_composite especially using ports. I see that there is some documentation regarding this but I was not able to fix it on my end.
Especially elements which already have a waveguide (probeline) already defined in their element class and needs to be connected to other waveguide_composite elements.

[Qvadi]

FYI, I am trying out another version of the default hanger_resonator as a custom element :). The new element works well just as is but I fail to add it as a two-port component into the waveguide_composite structure I am trying to build.
For it to work, I need to understand the general framework of adding elements into the waveguide_composite class based on ports. I see some funny things in Klayout after tinkering with the code already but still doesn't do what I want it to. Its not repeatable in some instances for me to document it here.
I will wait for your expert comments taking the default hanger_resonator as an example.

[iqmtestd]

Hi Qvadi,

By design, WaveguideComposite Nodes can use "simple elements", i.e. those that provide port_a and port_b. HangerResonator qualifies in principle and your example works for me. I've slightly changed it to have a bit more space (this is why waveguide drawing usually fails) and added a node after the resonator to show how it is embedded in the waveguide:

The used code:

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)

That said, it is not 100% supported. See the erroneous guiding line. I have to admit that HangerResonator is perhaps bit more complex than originally expected. This feature was designed for "simpler" elements, like a capacitor. This looks like a minor bug to me.

I understand that you actually want to use port_pl_a and port_pl_b. That works even better for me. Just changing the last two Nodes to:

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

I get an acceptable result:

[Qvadi]

Great! thank you.

[qpavsmi]

If you want to study working examples of the WaveguideComposite, you can try it out in the GUI.

1. Start KLayout GUI
2. Open the Element library for bottom left
3. Find Waveguide Composite from the list
4. Drag and drop it into the layout
5. Use the Partial tool above to drag the two nodes of the waveguide to stretch it, double click in the middle of the waveguide, to add more nodes, shape it any way you want.
6. Use Edit node tool to click one of the nodes and try out different parameters for it

Element field could be of interest to you since you can define elements to be placed at that specific node. We offer there elements that shouldn't have any problems working (i.e. HangerResonator is not there). Also try the other arguments to see what changes they cause.

After all that, if you want to see how the waveguide composition can be implemented in code, do the following:

1. Open from top toolbar Macros > Macro development
2. Set Console option below from Ruby to Python
3. In the file viewer on the left, choose Python panel, open [Local - python branch] > kqcircuits_scripts > macros > export > export_cells_as_code by double-clicking it
4. Make sure the layout you have currently open has the waveguide composition you are interested in. Then in Macro development window, press Shift+F5 (Run script from the current tab)
5. In the console you will see python code. If you copy it and paste it to a separate macro file and run it, it should generate the exact same waveguide composition.

Hope this helps!

[iqmtestd]

FYI: #69

[iqmtestd]

Hi @Qvadi,

This is fixed. Your original example (without the align=('port_pl_a', 'port_pl_b') part) works just fine:

The align parameter is not needed because the default port_a and port_b is now defined for the probeline part of the element, as this is what people usually would use in a waveguide anyway.