#############################################################################
# This script plots the dispersion relation and effective index of the two
# almost degenerate TE and TM modes supported by this anisotropic rib waveguide.
#
# Copyright Lumerical Solutions Inc. 2017
#############################################################################


clear;
closeall;

# mode calculation
switchtolayout;
run;
findmodes;

# extract TE mode
selectmode(1);
frequencysweep;
f = getdata("frequencysweep","f");
k0 = 2.0*pi/c*f;
neffTE = getdata("frequencysweep","neff");
betaTE = getdata("frequencysweep","beta");

# exctract TM mode
selectmode(2);
frequencysweep;
neffTM = getdata("frequencysweep","neff");
betaTM = getdata("frequencysweep","beta");

# plot kx vs wavenumber
plot(k0*1e-6,real(betaTM)*1e-6,real(betaTE)*1e-6,"k0 (rad/um)","kx (rad/um)","kx vs wavenumber (using FDE)");
legend("TM","TE");
setplot("x min",3.8);
setplot("x max",4.3);
setplot("y min",5.6);
setplot("y max",6.2);

# plot neff vs frequency
plot(c/f*1e6,real(neffTM),real(neffTE),"wavelength (um)","effective index","neff vs frequency (using FDE)");
legend("TM","TE");
setplot("x min",1.4);
setplot("x max",1.7);
setplot("y min",1.43);
setplot("y max",1.47);