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support adjoint gradients in cylindrical coordinate (#1749)
* cyl * remove print * fix * bug * update * update * cyl * update * update * cyl * fix * update * update * cyl * update * update * rebase fix * rebase * rebase fix * minor fix * clean up * cyl test * typo * fix Co-authored-by: Mo Chen <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,151 @@ | ||
| import meep as mp | ||
| try: | ||
| import meep.adjoint as mpa | ||
| except: | ||
| import adjoint as mpa | ||
| import numpy as np | ||
| from autograd import numpy as npa | ||
| from autograd import tensor_jacobian_product | ||
| import unittest | ||
| from enum import Enum | ||
| from utils import ApproxComparisonTestCase | ||
|
|
||
| np.random.seed(2) | ||
| resolution = 20 | ||
| dimensions = mp.CYLINDRICAL | ||
| m=0 | ||
| Si = mp.Medium(index=3.4) | ||
| SiO2 = mp.Medium(index=1.44) | ||
|
|
||
| sr = 6 | ||
| sz = 6 | ||
| cell_size = mp.Vector3(sr, 0, sz) | ||
| dpml = 1.0 | ||
| boundary_layers = [mp.PML(thickness=dpml)] | ||
|
|
||
| design_region_resolution = int(2*resolution) | ||
| design_r = 4.8 | ||
| design_z = 2 | ||
| Nx = int(design_region_resolution*design_r) | ||
| Nz = int(design_region_resolution*design_z) | ||
|
|
||
| fcen = 1/1.55 | ||
| width = 0.2 | ||
| fwidth = width * fcen | ||
| source_center = [0.1+design_r/2,0,(sz/2-dpml+design_z/2)/2] | ||
| source_size = mp.Vector3(design_r,0,0) | ||
| src = mp.GaussianSource(frequency=fcen,fwidth=fwidth) | ||
| source = [mp.Source(src,component=mp.Er, | ||
| center=source_center, | ||
| size=source_size)] | ||
|
|
||
| ## random design region | ||
| p = np.random.rand(Nx*Nz) | ||
| ## random epsilon perturbation for design region | ||
| deps = 1e-5 | ||
| dp = deps*np.random.rand(Nx*Nz) | ||
|
|
||
|
|
||
| def forward_simulation(design_params): | ||
| matgrid = mp.MaterialGrid(mp.Vector3(Nx,0,Nz), | ||
| SiO2, | ||
| Si, | ||
| weights=design_params.reshape(Nx,1,Nz)) | ||
|
|
||
| geometry = [mp.Block(center=mp.Vector3(0.1+design_r/2,0,0), | ||
| size=mp.Vector3(design_r,0,design_z), | ||
| material=matgrid)] | ||
|
|
||
| sim = mp.Simulation(resolution=resolution, | ||
| cell_size=cell_size, | ||
| boundary_layers=boundary_layers, | ||
| sources=source, | ||
| geometry=geometry, | ||
| dimensions=dimensions, | ||
| m=m) | ||
|
|
||
| frequencies = [fcen] | ||
| far_x = [mp.Vector3(5,0,20)] | ||
| mode = sim.add_near2far( | ||
| frequencies, | ||
| mp.Near2FarRegion(center=mp.Vector3(0.1+design_r/2,0 ,(sz/2-dpml+design_z/2)/2),size=mp.Vector3(design_r,0,0), weight=+1), | ||
| decimation_factor=10 | ||
| ) | ||
|
|
||
| sim.run(until_after_sources=1200) | ||
| Er = sim.get_farfield(mode, far_x[0]) | ||
| sim.reset_meep() | ||
|
|
||
| return abs(Er[0])**2 | ||
|
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||
|
|
||
| def adjoint_solver(design_params): | ||
|
|
||
| design_variables = mp.MaterialGrid(mp.Vector3(Nx,0,Nz),SiO2,Si) | ||
| design_region = mpa.DesignRegion(design_variables,volume=mp.Volume(center=mp.Vector3(0.1+design_r/2,0,0), size=mp.Vector3(design_r, 0,design_z))) | ||
| geometry = [mp.Block(center=design_region.center, size=design_region.size, material=design_variables)] | ||
|
|
||
| sim = mp.Simulation(cell_size=cell_size, | ||
| boundary_layers=boundary_layers, | ||
| geometry=geometry, | ||
| sources=source, | ||
| resolution=resolution, | ||
| dimensions=dimensions, | ||
| m=m) | ||
|
|
||
| far_x = [mp.Vector3(5,0,20)] | ||
| NearRegions = [mp.Near2FarRegion(center=mp.Vector3(0.1+design_r/2,0 ,(sz/2-dpml+design_z/2)/2),size=mp.Vector3(design_r,0,0), weight=+1)] | ||
| FarFields = mpa.Near2FarFields(sim, NearRegions ,far_x, decimation_factor=5) | ||
| ob_list = [FarFields] | ||
|
|
||
| def J(alpha): | ||
| return npa.abs(alpha[0,0,0])**2 | ||
|
|
||
| opt = mpa.OptimizationProblem( | ||
| simulation=sim, | ||
| objective_functions=J, | ||
| objective_arguments=ob_list, | ||
| design_regions=[design_region], | ||
| fcen=fcen, | ||
| df = 0, | ||
| nf = 1, | ||
| decay_fields=[mp.Er], | ||
| decay_by=1e-4, | ||
| maximum_run_time=1200) | ||
|
|
||
| f, dJ_du = opt([design_params]) | ||
| sim.reset_meep() | ||
|
|
||
| return f, dJ_du | ||
|
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||
|
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||
| class TestAdjointSolver(ApproxComparisonTestCase): | ||
|
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| def test_adjoint_solver_cyl_n2f_fields(self): | ||
| print("*** TESTING CYLINDRICAL Near2Far ADJOINT FEATURES ***") | ||
| adjsol_obj, adjsol_grad = adjoint_solver(p) | ||
|
|
||
| ## compute unperturbed S12 | ||
| S12_unperturbed = forward_simulation(p) | ||
|
|
||
| ## compare objective results | ||
| print("|Er|^2 -- adjoint solver: {}, traditional simulation: {}".format(adjsol_obj,S12_unperturbed)) | ||
| self.assertClose(adjsol_obj,S12_unperturbed,epsilon=1e-3) | ||
|
|
||
| ## compute perturbed S12 | ||
| S12_perturbed = forward_simulation(p+dp) | ||
|
|
||
| ## compare gradients | ||
| if adjsol_grad.ndim < 2: | ||
| adjsol_grad = np.expand_dims(adjsol_grad,axis=1) | ||
| adj_scale = (dp[None,:]@adjsol_grad).flatten() | ||
| fd_grad = S12_perturbed-S12_unperturbed | ||
| print("Directional derivative -- adjoint solver: {}, FD: {}".format(adj_scale,fd_grad)) | ||
| tol = 0.1 if mp.is_single_precision() else 0.01 | ||
| self.assertClose(adj_scale,fd_grad,epsilon=tol) | ||
|
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|
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||
| if __name__ == '__main__': | ||
| unittest.main() |
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