Lamd=(1.53, 0.000001, 1.55);
Dn1=2 e - 4;
V=1;
L=6000;
H=16000;
N=1.445;
Gap=0.535;
Delt=2 * PI * n * (1/lamd - 1/(2 * n * gap)); Mismatch between % modules
K=PI./lamd. * v * dn1; % cross coupling coefficient;
S=SQRT (k) ^ 2 - delt) ^ 2);

R=k. ^ 2 * sinh (s * l)/(s. ^ 2 * cosh (s * l) ^ 2 + delt. ^ 2 * sinh (s * l). ^ 2);

The plot (lamd, R)


hold on;