neff_slab = 1.444;
neff1 = real(getsweepdata('waveguide_width','neff1'))-neff_slab;
neff2 = real(getsweepdata('waveguide_width','neff2'))-neff_slab;
neff3 = real(getsweepdata('waveguide_width','neff3'))-neff_slab;
neff4 = real(getsweepdata('waveguide_width','neff4'))-neff_slab;
width = real(getsweepdata('waveguide_width','width'));

# plot in normalized units
plot(width*1e6,neff1,neff2,neff3,neff4,'waveguide width (um)','neff - neff_slab');
setplot('y min',0); setplot('y max',max(neff1));
legend('TE1','TE2/TM1','TE2/TM1','TM2');