implemented conic filtering on phase masks. The purpose of filtering is to remove large spatial variations of phase within the metasurface. On the other hand, the disadvantage of filtering is that high spatial variations might be required to achieve the desired target. A compromise needs to be reached: choose a small enough radius to avoid spurious phase values but that can still yield good overlap values.

2026-10-14 23:26:38 +00:00 · 2026-09-07 17:10:10 +02:00
parent ecffd9d8d9
commit b4e79330b1
3 changed files with 282 additions and 12 deletions
@@ -0,0 +1,87 @@
+import mpid as pid
+import numpy as np
+import os
+if not os.path.exists("results"):
+    os.makedirs("results")
+
+#Space grid definition
+N = 1025
+unit_cell_pitch = 700e-9
+
+n0 = 1.45
+n1 = 1.0
+n2 = 1.45
+mat_refr_index = np.array([n0, n1, n2])
+
+d0 = 476e-6 #propagation distance: source - MS1 [m]
+d1 = 510e-6 #propagation distance: MS1 - MS2 [m]
+d2 = d0 #propagation distance: MS2 - target [m]
+d = np.array([d0, d1, d2])
+
+ms_max_available_diameter = 122e-6 #[um]
+output_fiber_core_diameter = 19e-6 #[um]
+opt_max_eval = 140
+
+space_grid = pid.SpaceGrid(
+    side_pixels=N, 
+    unit_cell_pitch = unit_cell_pitch, 
+    prop_distances=d, 
+    materials_refr_index=mat_refr_index,
+)
+
+wavelength = 1.55e-6
+
+#define the sources
+source1 = pid.Source(input_field='fiber_modes/LP11_field_distribution_lda_1550_N_1025.npy', 
+                     wavelength=wavelength, 
+                     space_grid=space_grid, 
+                     field_norm=True)
+source2 = pid.Source(input_field='fiber_modes/LP21_field_distribution_lda_1550_N_1025.npy', 
+                     wavelength=wavelength, 
+                     space_grid=space_grid, 
+                     field_norm=True)
+
+
+target = pid.Target(input_field='fiber_modes/LP01_field_distribution_lda_1550_N_1025.npy', 
+                    center=(20e-6,0),
+                    associated_source=source1, 
+                    wavelength=wavelength, 
+                    space_grid=space_grid, 
+                    field_norm=True)
+target2 = pid.Target(input_field='fiber_modes/LP01_field_distribution_lda_1550_N_1025.npy', 
+                     center=(-20e-6,0),
+                     associated_source=source2, 
+                     wavelength=wavelength, 
+                     space_grid=space_grid, 
+                     field_norm=True) 
+
+#make a plot of sources and targets
+
+target.plot2D(plot_zoom_x=100, plot_zoom_y=100, choose_quantity="amplitude", save_name="results/target_plot")
+target2.plot2D(plot_zoom_x=100, plot_zoom_y=100, choose_quantity="amplitude", save_name="results/target2_plot")
+source1.plot2D(plot_zoom_x=100, plot_zoom_y=100, choose_quantity="amplitude", save_name="results/source1_plot")
+source2.plot2D(plot_zoom_x=100, plot_zoom_y=100, choose_quantity="amplitude", save_name="results/source2_plot")
+
+sim = pid.Simulation(
+    sources=[source1, source2],
+    targets=[target, target2],
+    central_wavelength=wavelength,
+    space_grid=space_grid,
+    n_cpu=1
+)
+
+opt_param_min = 0
+opt_param_max = 1
+
+sim.set_optimization(opt_param_min=opt_param_min, 
+                     opt_param_max=opt_param_max,
+                     ms_max_avail_diameter=ms_max_available_diameter,
+                     phase_mask_init_size=output_fiber_core_diameter,
+                     opt_max_eval=opt_max_eval,
+                     conic_filter_radius=1.5e-6)
+
+sim.run()
+
+best_opt_val, distances = sim.get_best_opt_and_distances()
+print("Best optimization value:", best_opt_val)
+print("Distances:", distances)