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import meep as mp
import argparse
import math
def main(args):
resolution = args.res
dpml = 1.0 # PML thickness
sz = 10 # size of computational cell (without PMLs)
sz = 10 + 2*dpml
cell_size = mp.Vector3(0,0,sz)
pml_layers = [mp.PML(dpml)]
wvl_min = 0.4 # min wavelength
wvl_max = 0.8 # max wavelength
fmin = 1/wvl_max # min frequency
fmax = 1/wvl_min # max frequency
fcen = 0.5*(fmin+fmax) # center frequency
df = fmax-fmin # frequency width
nfreq = 50 # number of frequency bins
# rotation angle (in degrees) of source: CCW around Y axis, 0 degrees along +Z axis
theta_r = math.radians(args.theta)
# plane of incidence is XZ
k = mp.Vector3(math.sin(theta_r),0,math.cos(theta_r)).scale(fmin)
# if normal incidence, force number of dimensions to be 1
if theta_r == 0:
dimensions = 1
else:
dimensions = 3
sources = [mp.Source(mp.GaussianSource(fcen,fwidth=df), component=mp.Ex, center=mp.Vector3(0,0,-0.5*sz+dpml))]
sim = mp.Simulation(cell_size=cell_size,
boundary_layers=pml_layers,
sources=sources,
k_point=k,
dimensions=dimensions,
resolution=resolution)
refl_fr = mp.FluxRegion(center=mp.Vector3(0,0,-0.25*sz))
refl = sim.add_flux(fcen, df, nfreq, refl_fr)
sim.run(until_after_sources=mp.stop_when_fields_decayed(50, mp.Ex, mp.Vector3(0,0,-0.5*sz+dpml), 1e-9))
empty_flux = mp.get_fluxes(refl)
empty_data = sim.get_flux_data(refl)
sim.reset_meep()
# add a block with n=3.5 for the air-dielectric interface
geometry = [mp.Block(mp.Vector3(mp.inf,mp.inf,0.5*sz), center=mp.Vector3(0,0,0.25*sz), material=mp.Medium(index=3.5))]
sim = mp.Simulation(cell_size=cell_size,
geometry=geometry,
boundary_layers=pml_layers,
sources=sources,
k_point=k,
dimensions=dimensions,
resolution=resolution)
refl = sim.add_flux(fcen, df, nfreq, refl_fr)
sim.load_minus_flux_data(refl, empty_data)
sim.run(until_after_sources=mp.stop_when_fields_decayed(50, mp.Ex, mp.Vector3(0,0,-0.5*sz+dpml), 1e-9))
refl_flux = mp.get_fluxes(refl)
freqs = mp.get_flux_freqs(refl)
for i in range(0,nfreq):
print("refl:, {}, {}, {}, {}".format(k.x,1/freqs[i],math.degrees(math.asin(k.x/freqs[i])),-refl_flux[i]/empty_flux[i]))
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('-res', type=int, default=200, help='resolution (default: 200 pixels/um)')
parser.add_argument('-theta', type=float, default=0, help='angle of incident planewave (default: 0 degrees)')
args = parser.parse_args()
main(args)
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