fdfd_tools/examples/fdfd.py

251 lines
7.8 KiB
Python

import importlib
import numpy
from numpy.linalg import norm
import meanas
from meanas import fdtd
from meanas.fdmath import vec, unvec
from meanas.fdfd import waveguide_3d, functional, scpml, operators
from meanas.fdfd.solvers import generic as generic_solver
import gridlock
from matplotlib import pyplot
import logging
logging.basicConfig(level=logging.DEBUG)
__author__ = 'Jan Petykiewicz'
def test0(solver=generic_solver):
dx = 50 # discretization (nm/cell)
pml_thickness = 10 # (number of cells)
wl = 1550 # Excitation wavelength
omega = 2 * numpy.pi / wl
# Device design parameters
radii = (1, 0.6)
th = 220
center = [0, 0, 0]
# refractive indices
n_ring = numpy.sqrt(12.6) # ~Si
n_air = 4.0 # air
# Half-dimensions of the simulation grid
xyz_max = numpy.array([1.2, 1.2, 0.3]) * 1000 + pml_thickness * dx
# Coordinates of the edges of the cells.
half_edge_coords = [numpy.arange(dx/2, m + dx, step=dx) for m in xyz_max]
edge_coords = [numpy.hstack((-h[::-1], h)) for h in half_edge_coords]
# #### Create the grid, mask, and draw the device ####
grid = gridlock.Grid(edge_coords, initial=n_air**2, num_grids=3)
grid.draw_cylinder(surface_normal=gridlock.Direction.z,
center=center,
radius=max(radii),
thickness=th,
eps=n_ring**2,
num_points=24)
grid.draw_cylinder(surface_normal=gridlock.Direction.z,
center=center,
radius=min(radii),
thickness=th*1.1,
eps=n_air ** 2,
num_points=24)
dxes = [grid.dxyz, grid.autoshifted_dxyz()]
for a in (0, 1, 2):
for p in (-1, 1):
dxes = meanas.fdfd.scpml.stretch_with_scpml(dxes, axis=a, polarity=p, omega=omega,
thickness=pml_thickness)
J = [numpy.zeros_like(grid.grids[0], dtype=complex) for _ in range(3)]
J[1][15, grid.shape[1]//2, grid.shape[2]//2] = 1
'''
Solve!
'''
sim_args = {
'omega': omega,
'dxes': dxes,
'epsilon': vec(grid.grids),
}
x = solver(J=vec(J), **sim_args)
A = operators.e_full(omega, dxes, vec(grid.grids)).tocsr()
b = -1j * omega * vec(J)
print('Norm of the residual is ', norm(A @ x - b))
E = unvec(x, grid.shape)
'''
Plot results
'''
pyplot.figure()
pyplot.pcolor(numpy.real(E[1][:, :, grid.shape[2]//2]), cmap='seismic')
pyplot.axis('equal')
pyplot.show()
def test1(solver=generic_solver):
dx = 40 # discretization (nm/cell)
pml_thickness = 10 # (number of cells)
wl = 1550 # Excitation wavelength
omega = 2 * numpy.pi / wl
# Device design parameters
w = 600
th = 220
center = [0, 0, 0]
# refractive indices
n_wg = numpy.sqrt(12.6) # ~Si
n_air = 1.0 # air
# Half-dimensions of the simulation grid
xyz_max = numpy.array([0.8, 0.9, 0.6]) * 1000 + (pml_thickness + 2) * dx
# Coordinates of the edges of the cells.
half_edge_coords = [numpy.arange(dx/2, m + dx/2, step=dx) for m in xyz_max]
edge_coords = [numpy.hstack((-h[::-1], h)) for h in half_edge_coords]
# #### Create the grid and draw the device ####
grid = gridlock.Grid(edge_coords, initial=n_air**2, num_grids=3)
grid.draw_cuboid(center=center, dimensions=[8e3, w, th], eps=n_wg**2)
dxes = [grid.dxyz, grid.autoshifted_dxyz()]
for a in (0, 1, 2):
for p in (-1, 1):
dxes = scpml.stretch_with_scpml(dxes,omega=omega, axis=a, polarity=p,
thickness=pml_thickness)
half_dims = numpy.array([10, 20, 15]) * dx
dims = [-half_dims, half_dims]
dims[1][0] = dims[0][0]
ind_dims = (grid.pos2ind(dims[0], which_shifts=None).astype(int),
grid.pos2ind(dims[1], which_shifts=None).astype(int))
src_axis = 0
wg_args = {
'slices': [slice(i, f+1) for i, f in zip(*ind_dims)],
'dxes': dxes,
'axis': src_axis,
'polarity': +1,
}
wg_results = waveguide_3d.solve_mode(mode_number=0, omega=omega, epsilon=grid.grids, **wg_args)
J = waveguide_3d.compute_source(E=wg_results['E'], wavenumber=wg_results['wavenumber'],
omega=omega, epsilon=grid.grids, **wg_args)
e_overlap = waveguide_3d.compute_overlap_e(E=wg_results['E'], wavenumber=wg_results['wavenumber'], **wg_args)
pecg = gridlock.Grid(edge_coords, initial=0.0, num_grids=3)
# pecg.draw_cuboid(center=[700, 0, 0], dimensions=[80, 1e8, 1e8], eps=1)
# pecg.visualize_isosurface()
pmcg = gridlock.Grid(edge_coords, initial=0.0, num_grids=3)
# pmcg.draw_cuboid(center=[700, 0, 0], dimensions=[80, 1e8, 1e8], eps=1)
# pmcg.visualize_isosurface()
def pcolor(v):
vmax = numpy.max(numpy.abs(v))
pyplot.pcolor(v, cmap='seismic', vmin=-vmax, vmax=vmax)
pyplot.axis('equal')
pyplot.colorbar()
ss = (1, slice(None), J.shape[2]//2+6, slice(None))
# pyplot.figure()
# pcolor(J3[ss].T.imag)
# pyplot.figure()
# pcolor((numpy.abs(J3).sum(axis=2).sum(axis=0) > 0).astype(float).T)
pyplot.show(block=True)
'''
Solve!
'''
sim_args = {
'omega': omega,
'dxes': dxes,
'epsilon': vec(grid.grids),
'pec': vec(pecg.grids),
'pmc': vec(pmcg.grids),
}
x = solver(J=vec(J), **sim_args)
b = -1j * omega * vec(J)
A = operators.e_full(**sim_args).tocsr()
print('Norm of the residual is ', norm(A @ x - b))
E = unvec(x, grid.shape)
'''
Plot results
'''
center = grid.pos2ind([0, 0, 0], None).astype(int)
pyplot.figure()
pyplot.subplot(2, 2, 1)
pcolor(numpy.real(E[1][center[0], :, :]).T)
pyplot.subplot(2, 2, 2)
pyplot.plot(numpy.log10(numpy.abs(E[1][:, center[1], center[2]]) + 1e-10))
pyplot.grid(alpha=0.6)
pyplot.ylabel('log10 of field')
pyplot.subplot(2, 2, 3)
pcolor(numpy.real(E[1][:, :, center[2]]).T)
pyplot.subplot(2, 2, 4)
def poyntings(E):
H = functional.e2h(omega, dxes)(E)
poynting = fdtd.poynting(e=E, h=H.conj(), dxes=dxes)
cross1 = operators.poynting_e_cross(vec(E), dxes) @ vec(H).conj()
cross2 = operators.poynting_h_cross(vec(H), dxes) @ vec(E).conj() * -1
s1 = 0.5 * unvec(numpy.real(cross1), grid.shape)
s2 = 0.5 * unvec(numpy.real(cross2), grid.shape)
s0 = 0.5 * poynting.real
# s2 = poynting.imag
return s0, s1, s2
s0x, s1x, s2x = poyntings(E)
pyplot.plot(s0x[0].sum(axis=2).sum(axis=1), label='s0', marker='.')
pyplot.plot(s1x[0].sum(axis=2).sum(axis=1), label='s1', marker='.')
pyplot.plot(s2x[0].sum(axis=2).sum(axis=1), label='s2', marker='.')
pyplot.plot(E[1][:, center[1], center[2]].real.T, label='Ey', marker='x')
pyplot.grid(alpha=0.6)
pyplot.legend()
pyplot.show()
q = []
for i in range(-5, 30):
e_ovl_rolled = numpy.roll(e_overlap, i, axis=1)
q += [numpy.abs(vec(E) @ vec(e_ovl_rolled).conj())]
pyplot.figure()
pyplot.plot(q, marker='.')
pyplot.grid(alpha=0.6)
pyplot.title('Overlap with mode')
pyplot.show()
print('Average overlap with mode:', sum(q)/len(q))
def module_available(name):
return importlib.util.find_spec(name) is not None
if __name__ == '__main__':
#test0()
# test1()
if module_available('opencl_fdfd'):
from opencl_fdfd import cg_solver as opencl_solver
test1(opencl_solver)
# from opencl_fdfd.csr import fdfd_cg_solver as opencl_csr_solver
# test1(opencl_csr_solver)
# elif module_available('magma_fdfd'):
# from magma_fdfd import solver as magma_solver
# test1(magma_solver)
else:
test1()