###########################################################################
#
# This file extracts the effective index from FEEM sweep data 
# and calculates effective index without any perturbation.
# It then and calculates the phase change as a function of input power
# 
# Copyright 2018, Lumerical Solutions, Inc.
###########################################################################

clear;
power = linspace(0.02,0.03,11); # total power in Watts
neff = matrix(length(power));

switchtolayout;
# find neff with no heating
setnamed('FEEM::nk import','enabled',0);
run("FEEM");
neff0 = real(pinch(getdata('FEEM','modeproperties.neff')));
neff0 = neff0(1);

switchtolayout;
# get neff from sweep
setnamed('FEEM::nk import','enabled',1);
runsweep("power");
neff = getsweepresult("power","neff");
neff = real(neff.neff);
neff = pinch(neff,1,1);

L = 200e-6;
lambda = 1.55e-6;
phase = 2*pi*(neff-neff0)*L/lambda;
plot(power, phase, 'power (W)','phase');