from __future__ import annotations
import numpy as np
import gdsfactory as gf
from gdsfactory.component import Component
from gdsfactory.components.rectangle import rectangle
from gdsfactory.components.taper import taper_strip_to_slab150
from gdsfactory.typings import (
ComponentSpec,
CrossSectionSpec,
Floats,
LayerSpec,
)
_gaps = (0.2,) * 10
_widths = (0.5,) * 10
[docs]
@gf.cell
def grating_coupler_rectangular_arbitrary_slab(
gaps: Floats = _gaps,
widths: Floats = _widths,
width_grating: float = 11.0,
length_taper: float = 150.0,
polarization: str = "te",
wavelength: float = 1.55,
taper: ComponentSpec = taper_strip_to_slab150,
layer_slab: LayerSpec | None = "SLAB150",
layer_grating: LayerSpec | None = None,
slab_offset: float = 2.0,
fiber_angle: float = 15,
cross_section: CrossSectionSpec = "xs_sc",
**kwargs,
) -> Component:
r"""Grating coupler uniform (grating with rectangular shape not elliptical). Therefore it needs a longer taper. Grating teeth are straight instead of elliptical.
Args:
gaps: list of gaps.
widths: list of widths.
width_grating: um.
length_taper: um.
polarization: 'te' or 'tm'.
wavelength: in um.
taper: function.
layer_slab: for pedestal.
layer_grating: optional layer for the grating. Defaults to the cross_section main layer.
slab_offset: from edge.
fiber_angle: in degrees.
cross_section: for input waveguide port.
kwargs: cross_section settings.
.. code::
side view
fiber
/ / / /
/ / / /
_|-|_|-|_|-|___ layer
layer_slab |
o1 ______________|
top view _________
/| | | | |
/ | | | | |
/taper_angle
/_ _| | | | |
wg_width | | | | | |
\ | | | | |
\ | | | | |
\ | | | | |
\|_|_|_|_|
<-->
taper_length
"""
xs = gf.get_cross_section(cross_section, **kwargs)
wg_width = xs.width
layer = layer_grating or xs.layer
c = Component()
taper = gf.get_component(
taper,
length=length_taper,
width2=width_grating,
width1=wg_width,
w_slab2=width_grating + 2 * slab_offset,
)
taper_ref = c << taper
c.add_port(port=taper_ref.ports["o1"], name="o1")
x0 = xi = taper_ref.xmax
widths = gf.snap.snap_to_grid(widths)
gaps = gf.snap.snap_to_grid(gaps)
for width, gap in zip(widths, gaps):
xi += gap + width / 2
cgrating = c.add_ref(
rectangle(
size=[width, width_grating],
layer=layer,
port_type=None,
centered=True,
)
)
cgrating.x = gf.snap.snap_to_grid(xi)
cgrating.y = 0
xi += width / 2
if layer_slab:
slab = c << rectangle(
size=(
gf.snap.snap_to_grid(xi - x0) + slab_offset,
width_grating + 2 * slab_offset,
),
layer=layer_slab,
port_type=None,
centered=True,
)
slab.xmin = x0
xport = np.round((xi + length_taper) / 2, 3)
c.add_port(
name="o2",
port_type=f"vertical_{polarization}",
center=(xport, 0),
orientation=0,
width=width_grating,
layer=layer,
)
c.info["polarization"] = polarization
c.info["wavelength"] = wavelength
if fiber_angle is not None:
c.info["fiber_angle"] = fiber_angle
return c
if __name__ == "__main__":
c = grating_coupler_rectangular_arbitrary_slab(slab_offset=2.0)
print(c.ports)
c.show(show_ports=True)
