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import unittest
import meep as mp
import math
import numpy as np
from numpy import linalg as LA
class TestNear2FarPeriodicBoundaries(unittest.TestCase):
def test_nea2far_periodic(self):
dpml = 1.0 # PML thickness
dsub = 3.0 # substrate thickness
dpad = 20.0 # padding between grating and PML
gp = 10.0 # grating period
gh = 0.5 # grating height
gdc = 0.5 # grating duty cycle
sx = dpml+dsub+gh+dpad+dpml
sy = gp
pml_layers = [mp.PML(thickness=dpml,direction=mp.X)]
wvl = 0.5 # center wavelength
fcen = 1/wvl # center frequency
df = 0.05*fcen # frequency width
src_pt = mp.Vector3(-0.5*sx+dpml+0.5*dsub)
sources = [mp.Source(mp.GaussianSource(fcen, fwidth=df), component=mp.Ez, center=src_pt, size=mp.Vector3(y=sy))]
glass = mp.Medium(index=1.5)
geometry = [mp.Block(material=glass, size=mp.Vector3(dpml+dsub,mp.inf,mp.inf), center=mp.Vector3(-0.5*sx+0.5*(dpml+dsub))),
mp.Block(material=glass, size=mp.Vector3(gh,gdc*gp,mp.inf), center=mp.Vector3(-0.5*sx+dpml+dsub+0.5*gh))]
k_point = mp.Vector3(0,0,0)
symmetries = [mp.Mirror(mp.Y)]
n2f_pt = mp.Vector3(-0.5*sx+dpml+dsub+gh+1.0)
dft_pt = mp.Vector3(0.5*sx-dpml)
res = [20,25,30]
norm = np.empty(3)
for j in range(3):
sim = mp.Simulation(resolution=res[j],
cell_size=mp.Vector3(sx,sy),
boundary_layers=pml_layers,
geometry=geometry,
k_point=k_point,
sources=sources,
symmetries=symmetries)
n2f_obj = sim.add_near2far(fcen, 0, 1, mp.Near2FarRegion(center=n2f_pt, size=mp.Vector3(y=sy)), nperiods=10)
dft_obj = sim.add_dft_fields([mp.Ez], fcen, 0, 1, center=dft_pt, size=mp.Vector3(y=sy))
sim.run(until_after_sources=300)
n2f_Ez = sim.get_farfields(n2f_obj, res[j], center=dft_pt, size=mp.Vector3(y=sy))
dft_Ez = sim.get_dft_array(dft_obj, mp.Ez, 0)
norm[j] = LA.norm(n2f_Ez['Ez']-dft_Ez[1:-1])
print("norm:, {}, {:.5f}".format(res[j],norm[j]))
sim.reset_meep()
self.assertGreater(norm[0],norm[1])
self.assertGreater(norm[1],norm[2])
if __name__ == '__main__':
unittest.main()
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