Add some older Theory projects from the past years

Functions/Theory/calcFWM/calcFwmPower.m

@@ -0,0 +1,48 @@
+function [P_fwm, eta, deltaBeta, Leff] = calcFwmPower( ...
+    f_i, f_j, f_k, f_0, Ds, alphaDbPerKm, Lkm, ...
+    P_i, P_j, P_k, gammaWInvKmInv, degeneracyFactor)
+% Calculate FWM power for a fiber with attenuation and phase mismatch.
+%
+% Inputs:
+%   f_i, f_j, f_k, f_0 : frequencies in Hz
+%   Ds                 : dispersion slope in ps / (nm^2 km)
+%   alphaDbPerKm       : attenuation in dB/km
+%   Lkm                : fiber length in km
+%   P_i, P_j, P_k      : launch powers in W
+%   gammaWInvKmInv     : nonlinear coefficient in 1/(W km)
+%   degeneracyFactor   : typically 3 for degenerate FWM, 6 for non-degenerate
+
+if nargin < 8 || isempty(P_i)
+    P_i = 1;
+end
+if nargin < 9 || isempty(P_j)
+    P_j = P_i;
+end
+if nargin < 10 || isempty(P_k)
+    P_k = 1;
+end
+if nargin < 11 || isempty(gammaWInvKmInv)
+    gammaWInvKmInv = 1;
+end
+if nargin < 12 || isempty(degeneracyFactor)
+    degeneracyFactor = 1;
+end
+
+[eta, deltaBeta] = calcFwmEfficiency(f_i, f_j, f_k, f_0, Ds, alphaDbPerKm, Lkm);
+
+alphaNpPerM = alphaDbPerKm .* log(10) ./ 10 ./ 1e3;
+Lm = Lkm .* 1e3;
+gammaWInvMInv = gammaWInvKmInv ./ 1e3;
+
+if abs(alphaNpPerM) < eps
+    Leff = Lm;
+else
+    Leff = (1 - exp(-alphaNpPerM .* Lm)) ./ alphaNpPerM;
+end
+
+P_fwm = degeneracyFactor .* eta .* ...
+    (gammaWInvMInv .* Leff).^2 .* ...
+    P_i .* P_j .* P_k .* ...
+    exp(-alphaNpPerM .* Lm);
+
+end