Optical fiber layers interference

Comments (1)

1. 

   Jose Romero reporter

   I begin my problem with small linspace, having good results:

   I put aspherical lense very near from the fiber:

   Now if we assume

   • the fiber position at z = 0.
   • f40 lense located at z=40mm
   • sensor located at f=80mm (2*f)

   the idea is to get the final field of small linespace and perform RS propagation until the lense. Get the x field and perform antoher RS propagation including the lense, But it not works at expected, maybe I make some mistake:

   ‌

   # -*- coding: utf-8 -*-
   """
   Created on Tue Sep  6 16:13:54 2022
   
   @author: j.romero
   """
   
   #-------------------------------------------------------------------
   # Import des modules
   
   
   from diffractio import degrees, eps, mm, np, num_max_processors, plt,sp, um
   from diffractio.scalar_fields_XZ import Scalar_field_XZ
   from diffractio.scalar_masks_X import Scalar_mask_X
   from diffractio.scalar_fields_X import Scalar_field_X
   from diffractio.scalar_masks_XZ import Scalar_mask_XZ
   from diffractio.scalar_sources_X import Scalar_source_X
   from matplotlib import rcParams
   
   
   # Tamaño de las imagenes
   rcParams['figure.figsize']=[8,6]
   rcParams['figure.dpi']=125
   
   
   #-------------------------------------------------------------------
   # Simulacion alrededor de la fibra
   
   
   # Definicion del espacio de simulacion en x et z
   x0 = np.linspace(-200 * um, 200 * um, 2048*4)
   z0 = np.linspace(-200 * um, 200 * um, 2048*4)
   
   # Largo de onda del laser
   wavelength = 0.660 * um
   
   # Inicializacion del campo u1
   u1 = Scalar_field_XZ(x=x0, z=z0, wavelength=wavelength)
   
   # Fuente plana
   u0 = Scalar_source_X(x=x0, wavelength=wavelength)
   u0.gauss_beam(A=1, x0=0 * um, z0=0 * um, w0=10 * um, theta=0. * degrees)
   u0.plane_wave(A=1, theta=0 * degrees)
   
   
   # Definicion de la fibra
   u1 = Scalar_mask_XZ(x=x0, z=z0, wavelength=wavelength, n_background=1.0)
   
   # 4 capas de fibra para analyzar
   u1.sphere( (0,0), 85 * um, 1.483, angle = 0)
   u1.sphere( (0,0), 75 * um, 1.443, angle = 0)
   u1.sphere( (0,0), 62.5 * um, 1.461, angle = 0)
   u1.sphere( (0,0), 2.5 * um, 1.462, angle = 0)
   
   # Afectacion del campo incidente
   u1.incident_field(u0)
   
   # Simulacion BMP en 2D
   u1.BPM(verbose=False)
   u1.draw(logarithm=True, normalize='maximum', draw_borders=True, scale='scaled');
   
   # Campo resultante
   u2 = u1.final_field()
   u2.draw();
   
   
   #-------------------------------------------------------------------
   # Simulacion desde la fibra hasta antes del lente en RS
   
   # Dejamos divergir el campo hasta antes del lente y amplifacamos el espacio
   f = 40*mm
   amp = 50
   u3=u2.RS(z=f, amplification=amp, verbose=False)
   
   # Sub muestreo del campo
   N = 4096
   u3.normalize()
   u4 = u3.cut_resample(x_limits=(-10*mm,10*mm), num_points = N, new_field=True)
   u4.draw(cut_value=0.02,logarithm=True, normalize='maximum')
   
   #-------------------------------------------------------------------
   # Definimos otro espacio donde multiplicamos el lente por el campo resulante anterior
   
   x1 = np.linspace(-10 * mm, 10 * mm,  N)
   
   # On defini la lentille
   t1 = Scalar_mask_X(x=x1, wavelength=wavelength)
   t1.lens(x0=0 * mm, radius=26.4 * mm, focal=f)
   
   t2 = t1 * u4
   
   t3 = t2.RS(z = f, new_field=True)
   t4 = t3.cut_resample(x_limits=(0,10*mm), new_field=True)
   t3.draw(cut_value=0.01,logarithm=True, normalize='maximum')
   

   BMP simulation (OK)

   Before lense (OK)

   RS after lense (KO)

   ‌

   ….

   Thanks for your reply

   ‌

   • 2022-09-07T13:24:10+00:00
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