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changing the grid system requires using a larger beamwaist for the input field. Effectively, the larger beam incides onto a larger number of unit-cells

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edoardo
2026-06-18 21:00:51 +02:00
parent 5e7ad710ba
commit 1668de238d
1 changed files with 13 additions and 3 deletions
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metaprop_fibermode_doublet.py
+13 -3
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@@ -22,7 +22,7 @@ opt_max_eval = 250
unit_cell_pitch = 400e-9 #equivalent to spatial sampling unit_cell_pitch = 400e-9 #equivalent to spatial sampling
Nx = 4096 #pixels per dimension Nx = 8192 #pixels per dimension
Ny = Nx Ny = Nx
S = Nx * Ny S = Nx * Ny
@@ -125,7 +125,7 @@ def get_fiber_mode_pattern():
for i in range(Nx): for i in range(Nx):
for j in range(Ny): for j in range(Ny):
r = np.sqrt(X[i,j]**2 + Y[i,j]**2) r = np.sqrt(X[i,j]**2 + Y[i,j]**2)
if r < 5*a: if r < 10*a:
phi = np.arctan2(Y[i,j], X[i,j]) phi = np.arctan2(Y[i,j], X[i,j])
if r < a:#inside core if r < a:#inside core
E_field[i,j] = jv(n_mode_sel,chi_co * r) / jv(n_mode_sel, chi_co * a) * np.cos(n_mode_sel * phi) E_field[i,j] = jv(n_mode_sel,chi_co * r) / jv(n_mode_sel, chi_co * a) * np.cos(n_mode_sel * phi)
@@ -136,10 +136,20 @@ def get_fiber_mode_pattern():
########################### ###########################
#initialize input field #initialize input field
beam_waist = 70e-6 beam_waist = 300e-6
gaussian_field = np.exp(-rho**2 / (beam_waist)**2) #Gaussian input field, flattened gaussian_field = np.exp(-rho**2 / (beam_waist)**2) #Gaussian input field, flattened
input_field_2d = (gaussian_field / np.sqrt(np.sum(np.abs(gaussian_field)**2))) #normalize the input field to have power = 1 input_field_2d = (gaussian_field / np.sqrt(np.sum(np.abs(gaussian_field)**2))) #normalize the input field to have power = 1
input_field = input_field_2d.flatten() #normalize the input field to have power = 1 input_field = input_field_2d.flatten() #normalize the input field to have power = 1
#make a plot and save the input field
plt.figure()
plt.imshow(np.abs(input_field_2d), extent=(-size_x*1e6/2, size_x*1e6/2, -size_y*1e6/2, size_y*1e6/2))
plt.title("Input Field Amplitude")
plt.xlabel("x (um)")
plt.ylabel("y (um)")
plt.colorbar()
plt.tight_layout()
plt.savefig("results/input_field_amplitude.pdf")
plt.close()
########################### ###########################
########################### ###########################