function prop_time = propagation_time(fiber_len_m)

    c = physconst('lightspeed');          % Speed of light in vacuum (m/s)
    n = 1.46;         % Refractive index of the fiber
    
    % Calculate the propagation speed in the fiber
    propagation_speed = c / n;
    
    % Calculate the propagation time
    prop_time = fiber_len_m ./ propagation_speed;
end