LinkSmooth

Full script

import math
from fnpcell import all as fp
from gpdk import all as pdk
from gpdk.technology import get_technology
from gpdk.technology.waveguide_factory import EulerBendFactory
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()

    fixed_bend = pdk.BendEuler90(radius_min=20, slab_square=True, waveguide_type=TECH.WG.FWG.C.WIRE)
    R = fixed_bend.raw_curve.radius_eff
    print("R", R)
    ms = 150
    s = 30
    e = -30
    points = [(0, s), (0, 2 * R + ms), (-2 * R - ms, 2 * R + ms), (-2 * R - ms, 0), (e, 0), (e, -80)]
    def bend_factory(central_angle: float):
        if abs(central_angle) != math.pi / 2:
            raise NotImplementedError()
        result = fixed_bend if central_angle > 0 else fixed_bend.v_mirrored()
        return result, R, ("op_0", "op_1")
    library += fp.LinkSmooth(
        points,
        start_type=TECH.WG.SWG.C.WIRE,
        end_type=TECH.WG.MWG.C.WIRE,
        link_type=TECH.WG.FWG.C.EXPANDED,
        bend_factory=bend_factory
    )
    # fp.export_gds(library, file=gds_file)
    fp.plot(library)

After running, we get the following figure, from which we can see that the starting port is SWG and the ending port is MWG. points contains a total of six points, of which the first and last points are the coordinates of the starting waveguide and the ending waveguide, and the rest of the points are path points.

In the path connecting the two ends of the waveguide, we use the defined form of bend_factory which waveguide is BendEuler90. This time we will change the first point in points to (-50,s), and run the script.

As you can see, the first corner does not meet the 90 degree case replaced with a normal EulerBend, the other several corners are still using the EulerBend90.