f = dlmread("strip-wvg-bands.dat");
plot(f(:,1),f(:,2:end),'b-',f(:,1),f(:,1)/1.45,'k-');
xlabel("wavevector k_x (units of 2\pi \mum^{-1})");
ylabel("frequency (units of 300 THz)");
axis([0 2 0 1]);
