光纤Bragg光栅反射谱

x=linspace(1.5365,1.5375,2048); y1=zeros(1,2048); y2=zeros(1,2048); y3=zeros(1,2048); for i=1:2048 b=2*1.45*pi/x(i)-pi/0.53; s1=sqrt((pi*2E-5/x(i))^2-b^2); s2=sqrt((pi*4E-5/x(i))^2-b^2); s3=sqrt((pi*8E-5/x(i))^2-b^2); y1(i)=((pi*2E-5/x(i))*sinh(s1*20000))^2/((s1*cosh(s1*20000))^2+(b*sinh(s1*20000))^2); y2(i)=((pi*4E-5/x(i))*sinh(s2*20000))^2/((s2*cosh(s2*20000))^2+(b*sinh(s2*20000))^2); y3(i)=((pi*8E-5/x(i))*sinh(s3*20000))^2/((s3*cosh(s3*20000))^2+(b*sinh(s3*20000))^2); end plot(x,y1,x,y2,':',x,y3,'--') xlabel('波长/μm') ylabel('归一化反射率') gtext('━△n=2E-5') gtext('┈△n=4E-5') gtext('┄△n=8E-5') axis([1.5366 1.5374 0 1])