from Berreman4x4 import c, pi
import matplotlib.pyplot as pyplot
n_i = 1.0 # incident medium is air
n_o = 2.0 # ordinary index of thin layer
n_e = 2.5 # extraordinary index of thin layer
##############################################################################
# Setting up the structure
# Front half-space (air)
air = Berreman4x4.IsotropicNonDispersiveMaterial(n_i)
front = Berreman4x4.IsotropicHalfSpace(air)
# Anisotropic substrate
uniaxialMaterialRef = Berreman4x4.UniaxialNonDispersiveMaterial(n_o, n_e)
back = Berreman4x4.HalfSpace()
s = Berreman4x4.Structure(front, [], back)
##############################################################################
# We reproduce figure 6.16
print("\nWe reproduce results from section 6.4.1 in " +
"'Spectroscopic Ellipsometry',\nby H. Fujiwara.\n")
print("*** Air / anisotropic sample ***")
print("We reproduce figure 6.16, p. 238...")
# Orientations of the anisotropic substrate
Φ_E = pi / 2 # 1st Euler angle
θ_E_list = [0, pi / 4, pi / 2] # 2nd Eulet angle
We consider a birefringence Δn = 0.10 and a thickness d = 4.33 µm. The first minimum should be at λ = 500 nm, or k0 = 1.257e7 m⁻¹. Note: Gooch-Tarry law does not take into account interferences between the two glass substrates. A glass with n = 1.55 minimizes the interferences. """ # Materials glass = Berreman4x4.IsotropicNonDispersiveMaterial(1.55) front = back = Berreman4x4.IsotropicHalfSpace(glass) # Liquid crystal oriented along the x direction (no, ne) = (1.5, 1.6) Dn = ne - no LC = Berreman4x4.UniaxialNonDispersiveMaterial(no, ne) R = Berreman4x4.rotation_v_theta(e_y, pi / 2) LC = LC.rotated(R) d = 4.33e-6 TN = Berreman4x4.TwistedMaterial(LC, d) # Inhomogeneous layer IL = Berreman4x4.InhomogeneousLayer(TN) # Structure s = Berreman4x4.Structure(front, [IL], back) # Normal incidence: Kx = 0.0 # Calculation parameters