Simulation doesn't work , it does't show the same image as the paper...

Hello there!

I do have a problem with this simulation. The image is not the same as that shown in this paper(attach file). The original code looks like this:

    clear all
format long
a = 52.5e-6;          %core radius of MMF
a0 = 4.1e-6;          %core radius of SMF
wl = 1550e-9;          %lambda
n01 = 1.4544;     n02 = 1.45;     %refractive index of SMF
n1 = 1.4574;      n2 = 1.4420;    %refractive index of MMF
V0 = 2*pi*a0/wl*sqrt(n01^2-n02^2);  %normalized frequency of SMF
w = a0/sqrt(log(2)*(0.65+1.619*V0^-1.5+2.879*V0^-6));  %Gauss beam FWHM
v = 1:30;             %order of core modes
V = 2*pi*a/wl*sqrt(n1^2-n2^2);        %normalized frequency of MMF
uv = (2*v-1/2)*pi/2;
wv = sqrt(V^2-uv.^2);

 up = 2*(w/a)^2*exp(-0.5*w^2/a*uv.^2);
 down1 = besselj(0,uv).^2 + besselj(1,uv).^2;
 down2 = besselk(1,wv).^2./besselk(0,wv).^2;
 down3 = besselj(0,uv).^2;
 down = down1+(down2-1).*down3;
 eta = real(up./down);         %power coupling efficency
%{
eta = 2*(w/a)^2*exp(-0.5*w^2/a*((2*v-1/2)*pi/2).^2)./ ...,
    (besselj(0,((2*v-0.5)*pi/2)).^2 + besselj(1,((2*v-0.5)*pi/2)).^2+ ...,
    (besselk(1,sqrt(V^2-((2*v-0.5)*pi/2).^2)).^2./besselk(0,sqrt(V^2-((2*v-0.5)*pi/2).^2)).^2 -1).* ...,
    besselj(0,((2*v-0.5)*pi/2)).^2);
%}
plot(v,eta,'*','markersize',5)
xlabel('Order of core modes')
ylabel('The power coupling efficiency  \eta_v of smf2mmf')

It doesn't work at all. I hope someone can give me a good advise, how to deal with that. Thank you!

Answer 1

[Image Analyst]

You can debug it yourself after you view this: http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/

[ZhiH]

Thanks for your help. But it doesn't work correctly, even after several times checking and debugging step by step.

Could you help me to debug it?

Thanks.

[Image Analyst]

Sorry, no. I don't know anything about tunable fiber lenses and don't have time to read the paper, understand it, and explain it to you. Good luck though.

http://matlab.wikia.com/wiki/FAQ#Can_you_program_up_the_algorithm_in_this_article_for_me_and_explain_it_to_me.3F

[ZhiH]

OK. Thanks all the same.