Contents

ODE45 equations to be solved

The following is considered: QPM

function dA = ode45equation(z,A,g,deltak,QPM,lcoh)
    dA=zeros(3,1);

QPM factor

Effectevely adds a pi phase shift of the induced
polarisation and hence the source term in the
wave-equations every time the wave has traveled
half a coherence length, lcoh
    if QPM == 0
        s=-1;
    else
        s = -(-1).^floor((z+lcoh/4)/(QPM*lcoh/2));
    end
Error using ode45equation (line 14)
Not enough input arguments.

Calculates the solution to the coupled differential equation

A(1) is the signal
A(2) is the idler
A(3) is the pump
    dA(1)   =  s*  1i*g*A(3)*conj(A(2))    *exp(1i*deltak*z)   ;
    dA(2)   =  s*  1i*g*A(3)*conj(A(1))    *exp(1i*deltak*z)   ;
    dA(3)   =  s*  1i*g*A(1)*A(2)          *exp(-1i*deltak*z)  ;

%     if( abs(A(1) + dA(1)) < 4e13)
%         disp('signal');
%         dA(1) = -A(1)+abs(A(1))*exp(1i*angle(dA(1)));
%     end
%
%     if( abs(A(2) + dA(2)) < 1.7733e11)
%         disp('idler');
%         dA(2) = -A(2)+abs(A(2))*exp(1i*angle(dA(2)));
%     end

%     if( abs(A(3) + dA(3)) < 5e14)
%         disp('pump');
%         dA(3) = -A(3)+abs(A(3))*exp(1i*angle(dA(3)));
%     end
end