%% Parameters
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.* 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'})
grid on; box on;
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');

mat2tikz_improved("C:\Users\Silas\Documents\6971e0b65b380ca6d71c837f\02_IMDD_System\tikz\mpi\laser_linewidth_vs_coherence.tikz");
%% 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