采用传输矩阵法求解光子晶体带隙

 1.单膜传输矩阵

 

 

mode=1;
n0=1;
theta0=0/180*pi;

n1=5.5225; 
h1=150E-9;
theta1=asin(n0*sin(theta0)/n1);


n2=1.9044;  
h2=150E-9; 
theta2=asin(n1*sin(theta1)/n2);
if mode==1
    p0=n0*cos(theta0);
    p1=n1*cos(theta1);
    p2=n2*cos(theta2);
else
    p0=n0/cos(theta0);
    p1=n1/cos(theta1);
    p2=n2/cos(theta2);
end

n=20;%layers
R=[];
lambda_set=200E-9:10E-9:1000E-9
for lambda0=lambda_set
    
    beta1=2*pi*sqrt(n1*h1)*cos(theta1)/lambda0;
    beta2=2*pi*sqrt(n2*h2)*cos(theta2)/lambda0;

    M1=[cos(beta1),-i*sin(beta1)/p1; -i*p1*sin(beta1),cos(beta1)];
    M2=[cos(beta2),-i*sin(beta2)/p2; -i*p2*sin(beta2),cos(beta2)];

    M=(M1*M2)^n;

    r_up  = (M(1,1)+M(1,2)*p0)*p0-(M(2,1)+M(2,2)*p0);
    r_down= (M(1,1)+M(1,2)*p0)*p0+(M(2,1)+M(2,2)*p0);
    r=r_up/r_down;
    R=[R (abs(r))^2];
end
plot(lambda_set,R);