mat_me.m

光纤SPR共振峰理论分析

function y1=mat_ME(lambda,N_index,D,theta1,NA,L,a0,R,r)
delta_x=theta1(1,2)-theta1(1,1);
n1=N_index(1);n2=N_index(2);n3=N_index(3);n4=N_index(4);
d1=D(1);d2=D(2);
t1=cos(theta1);
t2=sqrt(1-(n1*sin(theta1)/n2).^2);
t3=sqrt(1-(n1*sin(theta1)/n3).^2);
t4=sqrt(1-(n1*sin(theta1)/n4).^2);
k0=2*pi./lambda;
beta1=k0*n2*d1.*t2;
beta2=k0*n3*d2.*t3;
q1(1,:)=t1/n1;q2(1,:)=t2/n2;q3(1,:)=t3/n3;q4(1,:)=t4/n4;
q1(2,:)=t1*n1;q2(2,:)=t2*n2;q3(2,:)=t3*n3;q4(2,:)=t4*n4;
for ss2=1:2
for ss1=1:length(theta1)
M1=[cos(beta1(ss1)),-i./q2(ss2,ss1).*sin(beta1(ss1));-i*q2(ss2,ss1).*sin(beta1(ss1)),cos(beta1(ss1))];
M2=[cos(beta2(ss1)),-i./q3(ss2,ss1).*sin(beta2(ss1));-i*q3(ss2,ss1).*sin(beta2(ss1)),cos(beta2(ss1))];
mat=M1*M2;
r(1,ss1)=((mat(1,1)+mat(1,2)*q4(ss2,ss1))*q1(ss2,ss1)-(mat(2,1)+mat(2,2)*q4(ss2,ss1)))./((mat(1,1)+mat(1,2)*q4(ss2,ss1))*q1(ss2,ss1)+(mat(2,1)+mat(2,2)*q4(ss2,ss1)));
end
R(ss2,:)=abs(r).^2;
end
nn=fix(L./(a0*tan(theta1)));
P=exp(-2*(tan(asin(NA/n1)))^2./(tan(theta1)).^2);
for ss1=1:2
    tt=R(ss1,:).^nn;
F1(ss1,:)=tt(1,:).*P;
g(ss1)=(F1(ss1,1)+F1(ss1,end))/2*delta_x+sum(F1(ss1,2:end-1))*delta_x;
h(ss1)=(P(1,1)+P(1,end))/2*delta_x+sum(P(1,2:end-1))*delta_x;
end
%y1=(g(1)+g(2)))/h(2);
%y1=0.5*g(1)/h(1)+0.5;
y1=0.5*(g(1)/h(1)+g(2)/h(2));