Figure 7

(a, c, e, g, i, k) first mode S and FOM and (b, d, f, h, j, l) second mode S and FOM for n = 1, n = 1.1, n = 1.2, n = 1.4, n = 1.5 and n = 1.6 respectively.
(a, c, e, g, i, k) first mode S and FOM and (b, d, f, h, j, l) second mode S and FOM for n = 1, n = 1.1, n = 1.2, n = 1.4, n = 1.5 and n = 1.6 respectively.