figure_spotsize.m

pcf project dds sdfsd sdcsc sdcsc sdxcs gh fgb dfv fdgbvfg b fg fb fgbv gbfbf s bgtb fgbfv b fbv

%==========================================================================
% plot spot size in photonic crystal fiber with  values based on  effective
% index method - in three technics versus wavelength
%==========================================================================
% before using this m-file chek the wavelength in n_cl , n_eff functions,
% all of them have to get the same dimensions
clc
pitch = 2.3e-6 ;% pitch is distance between the center of two air hole
na = 1;% air refractive index
d = .5e-6; % aire hole radius
wavelength=.6e-6:.1e-6:2e-6;
nsi = get_nsi(wavelength);
ns = nsi;
n_cl = get_ncl(d,pitch,na);
n_eff = get_neff(pitch,n_cl);
R0 = 14.5*(10).^(-3);
y = 14.5*(10).^(-6);

% w_pcf is near field spot size or mode field radius

w_pcf=get_w1(pitch,ns,n_cl,n_eff,wavelength);
w = w_pcf/(.64*pitch);
h1 = plot(n_eff,w,'LineWidth',2);
set(h1,'Marker','.','Color',[1 0 0]);
hold on
% w_pcf is far field spot size or mode field radius
w_pcf=get_w2(pitch,ns,n_cl,n_eff,wavelength);
w = w_pcf/(.64*pitch);
h2 = plot(n_eff,w,'LineWidth',2);
set(h2,'Marker','o','Color',[0 0.498 0]);
% w_G is Gaussian spot size or mode field radius
w_G= get_WpcfG(pitch,ns,n_cl);
w = w_G/(.64*pitch);
h3 = plot(n_eff,w,'LineWidth',2);
set(h3,'Marker','pentagram','Color',[0 0 1]);
xlabel('\lambda');
ylabel('Spot Size / core radius');
legend('near field spot size', 'far field spot size','Gaussian spot size',...
       'Location', 'NorthWest')
annotation('textbox','String',{'d / \Lambda = 0. 5','\Lambda = 2.3 \mu m'},...
    'FitHeightToText','off','LineStyle','none',...
    'Position',[0.7908 0.5879 0.1076 0.1605]);
hold off