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ECOC Theroy stuff

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Silas Oettinghaus
2025-09-26 14:25:52 +02:00
parent 2c0e7a81aa
commit 9d63457030
9 changed files with 397 additions and 175 deletions
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38
projects/ECOC_2025/theory/coherence_length_plot.m
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@@ -1,32 +1,32 @@
%% Parameters
df = linspace(100e3,50e6,10000); % Laser FWHM linewidth [Hz]
df = linspace(1,50e6,10000); % Laser FWHM linewidth [Hz]
n_fiber = 1.467; % Fiber group index
c = 3e8; % Speed of light [m/s]
% Compute coherence length (1/e of mean-fringe decay)
tau_c = 1./(pi*df);
L_c = (c/n_fiber) .* tau_c; % Coherence length [m]
L_c = (c.* tau_c/n_fiber) ; % Coherence length [m]
%% Plot
figure('Color','w');
loglog(df/1e6, L_c, 'LineWidth',2,'LineStyle','-'); % linewidth in MHz
xticks([0.1, 1, 10, 50]);
yticks([1, 10, 100, 1000]);
yticklabels({'1','10','100','1000'})
% xticks([0.1, 1, 10, 50]);
% yticks([1, 10, 100, 1000]);
% yticklabels({'1','10','100','1000'})
grid on; box on;
xlabel('Laser linewidth [MHz]','FontSize',12,'Interpreter','none');
ylabel('Coherence length [m]','FontSize',12,'Interpreter','none');
title('Coherence Length vs. Laser Linewidth','FontSize',14,'Interpreter','none');
xlabel('Laser linewidth [MHz]','FontSize',12,'Interpreter','latex');
ylabel('Coherence length [m]','FontSize',12,'Interpreter','latex');
title('Coherence Length vs. Laser Linewidth','FontSize',14,'Interpreter','latex');
%% Annotate some key points
hold on;
freqs = [150e3, 1e6, 10e6, 50e6]; % [Hz]
for f = freqs
x = f/1e6;
y = (c/n_fiber) * (1/(pi*f));
scatter(x,y,'Marker','x','LineWidth',1,'MarkerEdgeColor','black');
text(x*1.1,y, sprintf('%.2f MHz', f/1e6), ...
'FontSize',10,'HorizontalAlignment','left');
end
% hold on;
% freqs = [150e3, 1e6, 10e6, 50e6]; % [Hz]
% for f = freqs
% x = f/1e6;
% y = (c/n_fiber) * (1/(pi*f));
% scatter(x,y,'Marker','x','LineWidth',1,'MarkerEdgeColor','black');
%
% text(x*1.1,y, sprintf('%.2f MHz', f/1e6), ...
% 'FontSize',10,'HorizontalAlignment','left');
%
% end