#!/usr/bin/env python
# coding: utf-8

# In[ ]:


import matplotlib.pyplot as plt
import numpy as np
from solcore.absorption_calculator import calculate_ellipsometry
from solcore import material, si
from solcore.structure import Structure, Layer


# First we defined a couple of materials, for example, GaAs and AlGAs

# In[ ]:


GaAs = material('GaAs')(T=300)
AlGaAs = material('AlGaAs')(T=300, Al=0.3)


# Now, let's build the structure. We don't add a substrate and assume that there is an infinitely thick absorbing<br>
# material in the back.

# In[ ]:


my_structure = Structure([
    Layer(si(40, 'nm'), material=AlGaAs),
    Layer(si(3000, 'nm'), material=GaAs),
])


# We want to calculate the ellipsometry of this structure as a function of the wavelength for a few angles

# In[ ]:


wavelength = np.linspace(400, 1000, 200)
angles = [65, 70, 75]


# In[ ]:


out = calculate_ellipsometry(my_structure, wavelength, angle=angles)


# This results must be taken with care. As the ellipsometry routine can only deal with coherent light, there might be<br>
# strange oscillations related with intereference in thick layers, something that should not happen.<br>
# Setting no_back_reflection=True (the default) should take care of most of this effects, but might add other unexpected<br>
# ones.

# In[ ]:


fig, ax1 = plt.subplots(1, 1)
ax2 = ax1.twinx()

ax1.plot(wavelength, out['psi'][:, 0], 'b', label=r'$\Psi$')
ax2.plot(wavelength, out['Delta'][:, 0], 'r', label=r'$\Delta$')
for i in range(1, len(angles)):
    ax1.plot(wavelength, out['psi'][:, i], 'b')
    ax2.plot(wavelength, out['Delta'][:, i], 'r')

ax1.set_xlabel("Wavelength (nm)")
ax1.set_ylabel(r'$\Psi$ (º)')
ax2.set_ylabel(r'$\Delta$ (º)')

ax1.legend(loc="upper left")
ax2.legend(loc="upper right")

plt.show()