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import math
import meep as mp
from meep import mpb
# Compute the band structure for a Bragg mirror consisting of a
# sinusoidally-varying dielectric index.
# The index will vary sinusoidally between index-min and index-max:
index_min = 1
index_max = 3
# Define a function of position p (in the lattice basis) that returns
# the material at that position. In this case, we use the function:
# index-min + 0.5 * (index-max - index-min)
# * (1 + cos(2*pi*x))
# This is periodic, and also has inversion symmetry.
def eps_func(p):
return mp.Medium(index=index_min + 0.5 * (index_max - index_min) *
(1 + math.cos(2 * math.pi * p.x)))
geometry_lattice = mp.Lattice(size=mp.Vector3(1)) # 1d cell
# We'll just make it the default material, so that it goes everywhere.
default_material = eps_func
k_points = mp.interpolate(9, [mp.Vector3(), mp.Vector3(x=0.5)])
resolution = 32
num_bands = 8
ms = mpb.ModeSolver(
num_bands=num_bands,
k_points=k_points,
geometry_lattice=geometry_lattice,
resolution=resolution,
default_material=default_material
)
def main():
# the TM and TE bands are degenerate, so we only need TM:
ms.run_tm()
if __name__ == '__main__':
main()
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