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| import numpy as np
import matplotlib as mpl
mpl.rcParams['figure.dpi']=100
import matplotlib.pylab as plt
import ceviche
from skimage.draw import disk
from ceviche.modes import insert_mode
from ceviche import fdfd_ez, jacobian
import autograd.numpy as npa
import collections
Slice = collections.namedtuple('Slice', 'x y')
def viz_sim(epsr, source1, source2, slices=[]):
simulation1 = fdfd_ez(omega1, dl, epsr, [Npml, Npml])
_, _, Ez1 = simulation1.solve(source1)
simulation2 = fdfd_ez(omega2, dl, epsr, [Npml, Npml])
_, _, Ez2 = simulation2.solve(source2)
fig, ax = plt.subplots(1, 3, constrained_layout=True, figsize=(9,3))
ceviche.viz.abs(Ez1, outline=epsr, ax=ax[0], cbar=False)
ceviche.viz.abs(Ez2, outline=epsr, ax=ax[1], cbar=False)
ceviche.viz.abs(epsr, ax=ax[2], cmap='Greys')
for sl in slices:
ax[0].plot(sl.x*np.ones(len(sl.y)), sl.y, 'w-', alpha=0.5)
ax[1].plot(sl.x*np.ones(len(sl.y)), sl.y, 'w-', alpha=0.5)
ax[0].set_title(r'$\lambda_1$ = %.2f $\mu$m' % (299792458/(omega1/2/np.pi)/1e-6))
ax[1].set_title(r'$\lambda_2$ = %.2f $\mu$m' % (299792458/(omega2/2/np.pi)/1e-6))
return (simulation1, simulation2, ax, fig)
def init_structure(Nx, Ny, Nwg, Nwd, Nox, Noy, Npml, edge_N, index_font, index_background):
epsr = np.ones((Nx, Ny)) * (index_font ** 2)
epsr[0:Nwg, (Ny-Nwd)//2:(Ny+Nwd)//2] = index_background ** 2
epsr[Nwg:Nwg+Nox, (edge_N) * Npml:(edge_N) * Npml+Noy] = index_background ** 2
epsr[Nwg+Nox:2*Nwg+Nox,(edge_N) * Npml: (edge_N) * Npml+Nwd] = index_background ** 2
epsr[Nwg+Nox:2*Nwg+Nox,(edge_N) * Npml+Noy-Nwd:(edge_N) * Npml+Noy] = index_background ** 2
input_slice = Slice(x=np.array(Npml+Nwg//2),
y=np.arange((Ny-Nwd)//2- Nwd, (Ny+Nwd)//2+Nwd))
output_slice1 = Slice(x=np.array(Nwg+Nox+Nwg//2),
y=np.arange(edge_N*Npml+Noy-2*Nwd, edge_N*Npml+Noy+Nwd))
output_slice2 = Slice(x=np.array(Nwg+Nox+Nwg//2),
y=np.arange( edge_N*Npml-Nwd, edge_N*Npml+2*Nwd))
return epsr, input_slice, output_slice1, output_slice2
def init_opt_structure(Nwg, circule_outer_radius, Npml, circule_inter_radius, epsr, index_font, index_background):
m = Nox // (circule_outer_radius * 2)
n = Noy // (circule_outer_radius * 2)
poles = []
for i in range(m):
for j in range(n):
rr, cc = disk((Nwg+2*circule_outer_radius*(j+0.5), (edge_N)*Npml+2*circule_outer_radius*(i+0.5)), circule_inter_radius)
poles.append([rr,cc])
epsr[rr,cc] = (index_font ** 2)
return epsr, poles
def set_opt_structure(poles, pole_index, epsr, index):
epsr[poles[pole_index][0],poles[pole_index][1]] = index ** 2
return epsr
if __name__ == "__main__":
omega1=2*np.pi*200e12
omega2=2*np.pi*230e12
dl = 20e-9
opt_size_x = 2400e-9
opt_size_y = 2400e-9
wg_len = 2000e-9
wg_width = 500e-9
Npml = 20
edge_N = 4
index_background = 3.47
index_font = 1.22
circule_outer_radius = 6
circule_inter_radius = 5
Nx = int((opt_size_x + 2 * wg_len)*10e9 / (dl*10e9))
Ny = int((opt_size_y)*10e9 / (dl*10e9) + 2 * edge_N * Npml)
Nox = int((opt_size_x*10e9) / (dl*10e9))
Noy = int((opt_size_y*10e9) / (dl*10e9))
Nwg = int(wg_len*10e9 / (dl*10e9))
Nwd = int(wg_width*10e9 / (dl*10e9))
epsr, input_slice, output_slice1, output_slice2 = init_structure(Nx, Ny, Nwg, Nwd, Nox, Noy, Npml, edge_N, index_font, index_background)
epsr, poles = init_opt_structure(Nwg, circule_outer_radius, Npml, circule_inter_radius, epsr, index_font, index_background)
source1 = insert_mode(omega1, dl, input_slice.x, input_slice.y, epsr, m=1)
source2 = insert_mode(omega2, dl, input_slice.x, input_slice.y, epsr, m=1)
probe1 = insert_mode(omega1, dl, output_slice1.x, output_slice1.y, epsr, m=1)
probe2 = insert_mode(omega2, dl, output_slice2.x, output_slice2.y, epsr, m=1)
epsr = set_opt_structure(poles, 0, epsr, index_background)
simulation1, simulation2, ax, fig = viz_sim(epsr, source1, source2, slices = [input_slice, output_slice1, output_slice2])
_, _, Ez1 = simulation1.solve(source1)
_, _, Ez2 = simulation2.solve(source2)
E01 = mode_overlap(Ez1, probe1)
E02 = mode_overlap(Ez2, probe2)
print(E01,E02)
plt.show()
|
