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 (lbda_min, lbda_max) = (200e-9, 1) # (m) k0_list = numpy.linspace(2 * pi / lbda_max, 2 * pi / lbda_min) # Plot setup
# Materials glass = Berreman4x4.IsotropicNonDispersiveMaterial(1.6) front = back = Berreman4x4.IsotropicHalfSpace(glass) # Liquid crystal oriented along the x direction (no, ne) = (1.5, 1.7) Dn = ne-no n_med = (ne + no)/2 LC = Berreman4x4.UniaxialNonDispersiveMaterial(no, ne) # ne along z R = Berreman4x4.rotation_v_theta(e_y, pi/2) # rotation round y LC = LC.rotated(R) # apply rotation from z to x # Cholesteric pitch: p = 0.65e-6 # One half turn of a right-handed helix: TN = Berreman4x4.TwistedMaterial(LC, p/2, angle=+pi, div=25) # Inhomogeneous layer, repeated layer, and structure IL = Berreman4x4.InhomogeneousLayer(TN) N = 5 # number half pitch repetitions h = N * p/2 L = Berreman4x4.RepeatedLayers([IL], N) s = Berreman4x4.Structure(front, [L], back) # Normal incidence: Kx = 0.0 # Calculation parameters lbda_min, lbda_max = 0.6e-6, 1.5e-6 # (m) lbda = numpy.linspace(lbda_min, lbda_max, 100) k0 = 2*pi/lbda
