changtu2.m

calculating fiber eigen modes

%求解两层线偏振模横截面场分布的程序

r1=4e-6;
nc=1.458;
n=1.45;
wl=1550e-9;
l=0;
neff=1.45438675775469;

k=2.*pi./wl;
beta=k.*neff;
u=r1.*sqrt(k.^2.*nc.^2-beta.^2);
w=r1.*sqrt(beta.^2-k.^2.*n.^2);

r=0:1/1000:r1;
u1=u.*r./r1;
Ey1=besselj(l,u1)./besselj(l,u);
plot(r,Ey1,'r')
hold on;

b=r1:1/1000:5*r1;
u2=w.*b./r1;
Ey2=besselk(l,u2)./besselk(l,w);
plot(b,Ey2,'r')
hold on;
grid on;