Hierarchical Gratings
This implementation of the gratings example uses cells and instances. First, the gratings are generated using array instances. Second, every grating is placed inside a separate cell and the stacking is achieved by placing these cells.
Note: With this approach you can create huge gratings very efficiently.
Code:
import klayout.db as db
import math
ly = db.Layout()
layer = ly.layer(1, 0)
top_cell = ly.create_cell("TOP")
width = 1.0
height = 10.0
length = 100.0
bar = ly.create_cell("BAR")
bar.shapes(layer).insert(db.DBox(0, 0, width, height))
def make_grating_cell(ly, bar, pitch, length):
"""
This function creates a grating cell with the given
bar cell and with the given pitch and length.
"""
# Note: KLayout will create a unique name itself:
grating = ly.create_cell("GRATING")
a = db.DVector(pitch, 0)
na = math.floor(length / pitch)
b = db.DVector() # not used
nb = 1
grating.insert(db.DCellInstArray(bar.cell_index(), db.DTrans(), a, b, na, nb))
return grating
y = 0.0
for pitch in [ 2.0, 2.5, 3.0 ]:
grating = make_grating_cell(ly, bar, pitch, length)
top_cell.insert(db.DCellInstArray(grating.cell_index(), db.DTrans(db.DVector(0, y))))
y += height * 1.5
ly.write("gratings_hierarchical.gds")
Result:
The top-level-only hierarchy view shows the cells:
