Analytical solution to calculate the small-signal single-pass gain of a fiber amplifier.
Includes standard parameters for erbium- or ytterbium-doped fiber amplifiers.
Use it to produce either of two types of plots:
1. Plot the gain versus pump power for various fiber lengths (at a single wavelength)
2. Plot the gain versus wavelength for various pump powers (at one or several fiber lengths)
Can also be used to calculate single-pass gain of lasers and thus predict the pump power necessary for lasing. (i.e. when the gain G_th is greater than the cavity losses L and output T: G_th = 1/((1-T)*(1-L)).
You can call the function from the command line/function/script; if you do this, the inputs are all optional but presumably you'll want to do at least some of them.
You can also use good ol' F5 to just run it with the defaults, editing them in the first few lines of the code.
% Example calls from command line:
% optional parameters
>>> plotFlag = 1; % optional, boolean if you want output plot or just the output values returned to the calling function
>>> loss = 2; % optional: excess loss in dB
% mode 1: plotting the gain vs. pump power for several lengths
>>> Pp = 50:5:100; % pump powers in mW
>>> L = [0.5 1 2 5]; % fiber length in m
>>> wl = 1550; % wavelength in nm
>>> G = EDFASinglePassGain_Analytical(wl,L,Pp,loss,plotFlag) % again, all inputs are basically optional, use the ones you need to change
% mode 2: plotting the gain vs. wavelength for several lengths, several pump powers
>>> Pp = 50:10:100; % in mW, use between 1 and 10 power values for helpful graphs
>>> L = [0.5 1 2 5]; % in m, use between 1 and 4 length values for helpful graphs
>>> wl = 1550; % signal wavelength in nm
>>> G = EDFASinglePassGain_Analytical(wl,L,Pp,loss,plotFlag)
Some CAVEATS are in order.
1. This solution does NOT incorporate ASE or strong-signal saturation effects. Therefore if you are interested in high-gain (>20 dB) or high-power (>100 uW input) amplifiers, you are probably not going to get good answers. Try my numerical simulator package "Fiber Lasers and Amplifiers Toolbox" instead.
2. If you care about quantitative results, particularly in matching experiments, you REALLY NEED to know your fiber parameters (core diameter, overlap, doping concentration). Otherwise the results will have no chance of matching reality.