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AsymmetricSplitter.py
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AsymmetricSplitter.py
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import sys
import argparse
import numpy as np
import meep as mp
from meep.adjoint import (OptimizationProblem, DFTCell, adjoint_options,
xHat, yHat, zHat, origin, FluxLine,
ParameterizedDielectric, FiniteElementBasis)
##################################################
##################################################
##################################################
class Splitter12(OptimizationProblem):
##################################################
##################################################
##################################################
def add_args(self, parser):
# add new problem-specific arguments
parser.add_argument('--dair', type=float, default=-1.0, help='')
parser.add_argument('--w_in', type=float, default=1.0, help='width of input waveguide')
parser.add_argument('--w_out1', type=float, default=0.5, help='width of output waveguide 1')
parser.add_argument('--w_out2', type=float, default=0.5, help='width of output waveguide 2')
parser.add_argument('--l_stub', type=float, default=3.0, help='length of waveguide input/output stub')
parser.add_argument('--l_design', type=float, default=2.0, help='length of design region')
parser.add_argument('--h_design', type=float, default=6.0, help='height of design region')
parser.add_argument('--eps_in', type=float, default=6.0, help='input waveguide permittivity')
parser.add_argument('--eps_out1', type=float, default=2.0, help='output waveguide 1 permittivity')
parser.add_argument('--eps_out2', type=float, default=12.0, help='output waveguide 2 permittivity')
parser.add_argument('--nfe', type=int, default=2, help='number of finite elements per unit length')
# set problem-specific defaults for existing (general) arguments
parser.set_defaults(fcen=0.5)
parser.set_defaults(df=0.2)
parser.set_defaults(dpml=1.0)
##################################################
##################################################
##################################################
def init_problem(self, args):
#----------------------------------------
# size of computational cell
#----------------------------------------
lcen = 1.0/args.fcen
dpml = 0.5*lcen if args.dpml==-1.0 else args.dpml
dair = 0.5*args.w_in if args.dair==-1.0 else args.dair
sx = dpml + args.l_stub + args.l_design + args.l_stub + dpml
sy = dpml + dair + args.h_design + dair + dpml
cell_size = mp.Vector3(sx, sy, 0.0)
#----------------------------------------
#- design region
#----------------------------------------
design_center = origin
design_size = mp.Vector3(args.l_design, args.h_design, 0.0)
design_region = mp.Volume(center=design_center, size=design_size)
#----------------------------------------
#- objective regions
#----------------------------------------
x_in = -0.5*(args.l_design + args.l_stub)
x_out = +0.5*(args.l_design + args.l_stub)
y_out1 = +0.25*args.h_design
y_out2 = -0.25*args.h_design
flux_in = FluxLine(x_in, 0.0, 2.0*args.w_in, mp.X, 'in')
flux_out1 = FluxLine(x_out, y_out1, 2.0*args.w_out1, mp.X, 'out1')
flux_out2 = FluxLine(x_out, y_out2, 2.0*args.w_out2, mp.X, 'out2')
objective_regions = [flux_in, flux_out1, flux_out2]
#----------------------------------------
#- optional extra regions for visualization if the --full-dfts options is present.
#----------------------------------------
extra_regions = [mp.Volume(center=origin, size=cell_size)] if args.full_dfts else []
#----------------------------------------
# forward source region
#----------------------------------------
source_center = (x_in - 0.25*args.l_stub)*xHat
source_size = 2.0*args.w_in*yHat
#----------------------------------------
# basis set
#----------------------------------------
basis = FiniteElementBasis(args.l_design, args.h_design, args.nfe)
#----------------------------------------
#- objective function
#----------------------------------------
fstr = ( 'Abs(P1_out1)**2'
+ '+0.0*(P1_out1 + M1_out1)'
+ '+0.0*(P1_out2 + M1_out2)'
+ '+0.0*(P1_in + M1_in + S_out1 + S_out2 + S_in)'
)
#----------------------------------------
#- internal storage for variables needed later
#----------------------------------------
self.args = args
self.dpml = dpml
self.cell_size = cell_size
self.basis = basis
self.design_center = origin
self.design_size = design_size
self.source_center = source_center
self.source_size = source_size
return fstr, objective_regions, extra_regions, design_region, basis
##############################################################
##############################################################
##############################################################
def create_sim(self, beta_vector, vacuum=False):
args=self.args
sx=self.cell_size.x
x_in = -0.5*(args.l_design + args.l_stub)
x_out = +0.5*(args.l_design + args.l_stub)
y_out1 = +0.25*args.h_design
y_out2 = -0.25*args.h_design
wvg_in = mp.Block( center=mp.Vector3(x_in,0.0),
size=mp.Vector3(args.l_stub,args.w_in),
material=mp.Medium(epsilon=args.eps_in))
wvg_out1 = mp.Block( center=mp.Vector3(x_out,y_out1),
size=mp.Vector3(args.l_stub,args.w_out1),
material=mp.Medium(epsilon=args.eps_out1))
wvg_out2 = mp.Block( center=mp.Vector3(x_out,y_out2),
size=mp.Vector3(args.l_stub,args.w_out2),
material=mp.Medium(epsilon=args.eps_out2))
design = mp.Block( center=origin,
size=mp.Vector3(args.l_design,args.h_design),
epsilon_func=ParameterizedDielectric(self.design_center,
self.basis,
beta_vector)
)
geometry=[wvg_in, wvg_out1, wvg_out2, design]
envelope = mp.GaussianSource(args.fcen,fwidth=args.df)
amp=1.0
if callable(getattr(envelope, "fourier_transform", None)):
amp /= envelope.fourier_transform(args.fcen)
sources=[mp.EigenModeSource(src=envelope,
center=self.source_center,
size=self.source_size,
eig_band=self.args.source_mode,
amplitude=amp
)
]
sim=mp.Simulation(resolution=args.res, cell_size=self.cell_size,
boundary_layers=[mp.PML(args.dpml)], geometry=geometry,
sources=sources)
if args.complex_fields:
sim.force_complex_fields=True
return sim
######################################################################
# if executed as a script, we look at our own filename to figure out
# the name of the class above, create an instance of this class called
# opt_prob, and call its run() method.
######################################################################
if __name__ == '__main__':
opt_prob=globals()[__file__.split('/')[-1].split('.')[0]]()
opt_prob.run()