Last change
on this file since 178 was 33, checked in by Rick van der Zwet, 15 years ago |
Restored acc. version
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1 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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2 | % This function calculates the Second Harmonic Generation
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3 | % of a Gaussian of frequencies with a given phase function.
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4 | %
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5 | % phi - an input COLUMN vector, containing the phase function.
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6 | % SHG - the output of the calculation; scalar.
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7 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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8 |
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9 | function [SHG] = SHG(phi);
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10 |
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11 | %constant for consistency with the Fortran Calculation...
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12 | c_fortran = 153.7687;
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13 |
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14 | % Generate the Gaussian and the phase function consistently.
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15 | Np = length(phi(:,1));
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16 | Nv = 4000;
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17 | v = linspace(-300,300,Nv); %Linearly Spaced Vector
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18 | G = 40;
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19 | Ain = exp(-(v/G).^2); %The Gaussian of Frequencies
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20 |
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21 | %Distribute the phase function according to the desired resolution
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22 | step = round((2600-1400)/Np);
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23 | step = step + (step==1);
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24 | phase = zeros(1,Nv);
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25 | k = 1;
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26 | for j = 1400:step:2600-step+1,
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27 | phase([j:j+step-1]) = phi(k);
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28 | if (k < Np)
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29 | k = k+1;
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30 | else
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31 | k = Np;
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32 | end
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33 | end
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34 | % *** The Core: SHG *** %
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35 |
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36 | %Fourier Transform with phase shift (phi) on the Gaussian *Ain*
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37 | E_t = fftshift(ifft(fftshift(exp(i*phase).*Ain)));
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38 |
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39 | %plot(abs(E_t));
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40 | %Integrate the result to yield the SHG
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41 | SHG = sum(abs(E_t).^4)/c_fortran;
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42 |
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43 |
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44 | %%%%%%%%%%%%%%%%%%%%%%%%%%% E O F %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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