Matlab实现FBG反射谱透射率仿真

L=0.01; neff=1.447; c=1*1e-7/(2*neff); deltaneff=0.0004; N=100; M=2000; lamda1=1548; lamda2=1552; lamda=linspace(lamda1*1e-9,lamda2*1e-9,M); deltalamda=(lamda2*1e-9-lamda1*1e-9)/(M-1); for k=1:M F=[1,0;0,1]; for n=1:N deltaneff_z=deltaneff; %g=4; % deltaneff_z=deltaneff*exp(-g*g*((2*n-1-N)/(2*N))^2); % H=0.5; %deltaneff_z=deltaneff*(1+H*cos(pi*(2*n-1-N)/N))/(1+H); lamdaD=1550*1e-9-L*neff*c+2*neff*c*(L*n/N-0.5*L/N); sigma=2*pi*neff*(1/lamda(k)-1/lamdaD)+2*pi*deltaneff_z/lamda(k)+(4*pi*neff)*c*(2*(neff+deltaneff))*(-L/2+n*L/N)/lamdaD^2; kac=pi*deltaneff_z/lamda(k); RB=sqrt(kac^2-sigma^2)+eps; F=F*[cosh(RB*L/N)-(sigma/RB)*sinh(RB*L/N)*1i,-(kac/RB)*sinh(RB*L/N)*1i;(kac/RB)*sinh(RB*L/N)*1i,cosh(RB*L/N)+(sigma/RB)*sinh(RB*L/N)*1i]; end R(k)=(abs(F(2,1)/(F(1,1)+eps)))^2; z=F(2,1)/(F(1,1)+eps); Q(k)=angle(z); if Q(k)<0 %angle0-2pi Q(k)=2*pi+Q(k); end end for a=2:M-1 if abs(Q(a)-Q(a+1))>=pi dQ(a)=(Q(a)-Q(a-1))/deltalamda; else dQ(a)=(Q(a+1)-Q(a))/deltalamda; end end dQ(1)=dQ(2); lamda1=lamda(1:M-1); tao=(-1/(2*pi*3*1e8))*(lamda1.*lamda1).*dQ; hold on; %subplot(1,2,1) plot(lamda,R,'k') title('反射谱') hold off %{ hold on; %subplot(1,2,2) plot(lamda1,tao,'r') title('时延')1 hold off %}