Extension of the ports
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``Extended`` class can be used to implement the device port in situations where the device port extension is required. A detailed illustration of this function definition is given in ``gpdk``> ``routing`` > ``extended.py``

Extended
^^^^^^^^^^^^^^^^^^^^^^

Full script
-------------------
::

    from numbers import Number
    from typing import List, Mapping, Optional, Tuple

    from fnpcell import all as fp
    from gpdk.components.straight.straight import Straight
    from gpdk.routing.auto_transitioned.auto_transitioned import AutoTransitioned
    from gpdk.technology import get_technology



    class Extended(fp.PCell):
        """
        Attributes:
            device: device whose ports need to be extended
            lengths: dict with port name as key, length as value, "*" means every other port
            waveguide_type: type of generated waveguide

        Examples:
        ```python
        TECH = get_technology()
            device = Extended(device=Mmi(waveguide_type=TECH.WG.FWG.C.WIRE), lengths={"*": 10, "op_0": 20, "op_1": 30})
        fp.plot(device)
        ```
        ![Extended](images/extended.png)
        """

        device: fp.IDevice = fp.DeviceParam()
        lengths: Mapping[str, float] = fp.MappingParam(K=str, V=Number, immutable=True)
        waveguide_type: Optional[fp.IWaveguideType] = fp.WaveguideTypeParam(required=False)

        def build(self) -> Tuple[fp.InstanceSet, fp.ElementSet, fp.PortSet]:
            insts, elems, ports = super().build()
            device = self.device
            lengths = self.lengths
            waveguide_type = self.waveguide_type
            instance = device if waveguide_type is None else AutoTransitioned(device=device, waveguide_types={key: waveguide_type for key in lengths})

            joints: List[Tuple[fp.IOwnedTerminal, fp.IOwnedTerminal]] = []
            straight_ports: List[fp.IOwnedTerminal] = []
            for port in instance.ports:
                if isinstance(port, fp.IOwnedPort) and not port.disabled:
                    length = lengths.get(port.name) or lengths.get("*")
                    if length is not None:
                        if waveguide_type is not None:
                            length -= fp.distance_between(device[port.name].position, instance[port.name].position)
                        assert length > 0 or fp.is_zero(length), f"extend length of {port.name} is too short"
                        if length > 0:
                            s = Straight(length=length, waveguide_type=port.waveguide_type)
                            joints.append(port <= s["op_0"])
                            port_name = port.name
                            straight_ports.append(s["op_1"].with_name(fp.Hidden(port_name) if port.hidden else port_name))

            used_port_names = set(port.name for port in straight_ports)
            unused_ports = [port for port in instance.ports if port.name not in used_port_names]
            connected = fp.Connected(
                joints=joints,
                ports=straight_ports + unused_ports,
            )
            insts += connected
            ports += connected.ports
            return insts, elems, ports


    if __name__ == "__main__":
        from gpdk.util.path import local_output_file

        gds_file = local_output_file(__file__).with_suffix(".gds")
        library = fp.Library()

        TECH = get_technology()
        # =============================================================
        # fmt: off
        from gpdk.components.mmi.mmi import Mmi
        from gpdk.components.ring_resonator.ring_resonator import RingResonator

        library += Extended(device=Mmi(waveguide_type=TECH.WG.FWG.C.WIRE), lengths={"*": 10, "op_0": 20, "op_1": 30})
        library += Extended(device=RingResonator(ring_radius=10, bottom_spacing=0.1, top_spacing=0.1, ring_type=TECH.WG.FWG.C.WIRE, bottom_type=TECH.WG.FWG.C.WIRE, top_type=TECH.WG.FWG.C.WIRE), lengths={"op_0": 1, "op_1": 1, "op_2": 1, "op_3": 1})

        # fmt: on
        # =============================================================
        fp.export_gds(library, file=gds_file)
        # fp.plot(library)


Section Script Definition
-------------------------------------

Create extended ports and export layout
=============================================
::

    if __name__ == "__main__":
        from pathlib import Path

        gds_file = Path(__file__).parent / "local" / Path(__file__).with_suffix(".gds").name
        library = fp.Library()

        TECH = get_technology()
        # =============================================================
        # fmt: off
        from gpdk.components.mmi.mmi import Mmi
        from gpdk.components.ring_resonator.ring_resonator import RingResonator

        library += Extended(device=Mmi(waveguide_type=TECH.WG.FWG.C.WIRE), lengths={"*": 10, "op_0": 20, "op_1": 30})
        library += Extended(device=RingResonator(ring_radius=10, bottom_spacing=0.1, top_spacing=0.1, ring_type=TECH.WG.FWG.C.WIRE, bottom_type=TECH.WG.FWG.C.WIRE, top_type=TECH.WG.FWG.C.WIRE), lengths={"op_0": 1, "op_1": 1, "op_2": 1, "op_3": 1})

        # fmt: on
        # =============================================================
        fp.export_gds(library, file=gds_file)
        # fp.plot(library)


Here we implement the device port extension by using the ``Extended`` class, where ``device`` receives the devices that need to be extended, ``waveguide_type`` receives the type of the extended waveguide, and ``lengths`` receives the length of each port that needs to be extended. The following figure shows the result of extending the port along.

GDS Layout
-----------------

.. image:: ../images/extend1.png