analyticalforpowerflowequation2.m

来自「用于描绘与计算不同角度入射进光纤的光在传输过程中的变化过程」· M 代码 · 共 25 行

D=7.5e-4;
%required from the paper "Ner mothod to calculate mode conversion
%coefficients in SI multimode optical fibers",2003
A=1.37;
%second order multiplicative factor in the series expansion of the power loss coefficient
b=4*(A*D)^0.5;
t=-30:0.05:30;
%the critical angle measure in air
z=0.1:0.1:10;% a coordinate along the fiber axis from the unput fiber end
[T,Z]=meshgrid(t,z);
S=T.*3.14./180;
% s is the propagation angle with respect to the core axis
X=(A/D)^0.5.*S.^2;
t0=25*3.14/180;
%the launched angle
x0=(A/D)^0.5*t0^2;
M=(4*x0.*X).^0.5.*exp(-0.5*b.*Z)./(1-exp(-b.*Z));
I0=BESSELI(0,M);%the modified Bessel function of order zero
P=exp(-(x0+X).*(1+exp(-b.*Z))./(2.*(1-exp(-b.*Z)))).*(exp(-0.5*b.*Z)./(1-exp(-b.*Z))).*I0;
%assuming that the input power distribution is the Dirac delta function
%P(x,0)=delta(x-x0)
mesh(T,Z,P);