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import matplotlib.pyplot as plt
import numpy as np
import meep as mp
resolution = 50 # pixels/μm
cell_size = mp.Vector3(14, 14)
pml_layers = [mp.PML(thickness=2)]
# rotation angle (in degrees) of waveguide, counter clockwise (CCW) around z-axis
rot_angle = np.radians(20)
w = 1.0 # width of waveguide
geometry = [
mp.Block(
center=mp.Vector3(),
size=mp.Vector3(mp.inf, w, mp.inf),
e1=mp.Vector3(x=1).rotate(mp.Vector3(z=1), rot_angle),
e2=mp.Vector3(y=1).rotate(mp.Vector3(z=1), rot_angle),
material=mp.Medium(epsilon=12),
)
]
fsrc = 0.15 # frequency of eigenmode or constant-amplitude source
bnum = 1 # band number of eigenmode
kpoint = mp.Vector3(x=1).rotate(mp.Vector3(z=1), rot_angle)
compute_flux = True # compute flux (True) or plot the field profile (False)
eig_src = True # eigenmode (True) or constant-amplitude (False) source
if eig_src:
sources = [
mp.EigenModeSource(
src=mp.GaussianSource(fsrc, fwidth=0.2 * fsrc)
if compute_flux
else mp.ContinuousSource(fsrc),
center=mp.Vector3(),
size=mp.Vector3(y=3 * w),
direction=mp.NO_DIRECTION,
eig_kpoint=kpoint,
eig_band=bnum,
eig_parity=mp.EVEN_Y + mp.ODD_Z if rot_angle == 0 else mp.ODD_Z,
eig_match_freq=True,
)
]
else:
sources = [
mp.Source(
src=mp.GaussianSource(fsrc, fwidth=0.2 * fsrc)
if compute_flux
else mp.ContinuousSource(fsrc),
center=mp.Vector3(),
size=mp.Vector3(y=3 * w),
component=mp.Ez,
)
]
sim = mp.Simulation(
cell_size=cell_size,
resolution=resolution,
boundary_layers=pml_layers,
sources=sources,
geometry=geometry,
symmetries=[mp.Mirror(mp.Y)] if rot_angle == 0 else [],
)
if compute_flux:
tran = sim.add_flux(
fsrc, 0, 1, mp.FluxRegion(center=mp.Vector3(x=5), size=mp.Vector3(y=14))
)
sim.run(until_after_sources=50)
res = sim.get_eigenmode_coefficients(
tran,
[1],
eig_parity=mp.EVEN_Y + mp.ODD_Z if rot_angle == 0 else mp.ODD_Z,
direction=mp.NO_DIRECTION,
kpoint_func=lambda f, n: kpoint,
)
print(
"flux:, {:.6f}, {:.6f}".format(
mp.get_fluxes(tran)[0], abs(res.alpha[0, 0, 0]) ** 2
)
)
else:
sim.run(until=100)
sim.plot2D(
output_plane=mp.Volume(center=mp.Vector3(), size=mp.Vector3(10, 10)),
fields=mp.Ez,
field_parameters={"alpha": 0.9},
)
plt.show()
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