計算脈沖在非線性耦合器中演化的Matlab 程序 <CIy|&J6  
c+bOp 05o-  
%  This Matlab script file solves the coupled nonlinear Schrodinger equations of 1UwpLd
  
%  soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of ,WKWin  
%  Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear hgmo b"o  
%   pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004 RHIGNzSz  
XZew$Om[  
%fid=fopen('e21.dat','w'); }Y=X{3+~.  
N = 128;                       % Number of Fourier modes (Time domain sampling points) =9;2(<A  
M1 =3000;              % Total number of space steps gN
j~o^6|@  
J =100;                % Steps between output of space .zQ'}H1.C  
T =10;                  % length of time windows:T*T0 R/|2s  
T0=0.1;                 % input pulse width l.Y
q4qW  
MN1=0;                 % initial value for the space output location lI&5.,2MP  
dt = T/N;                      % time step U'Mxf'q  
n = [-N/2:1:N/2-1]';           % Index g4U`Qf3  
t = n.*dt;   LV6BSQyQ  
u10=1.*sech(1*t);              % input to waveguide1 amplitude: power=u10*u10 _enS_R  
u20=u10.*0.0;                  % input to waveguide 2 FhAYk  
u1=u10; u2=u20;                 [a2Q ^ab  
U1 = u1;   FDQP|,  
U2 = u2;                       % Compute initial condition; save it in U tT`{xM  
ww = 4*n.*n*pi*pi/T/T;         % Square of frequency. Note i^2=-1. *`WD/fG  
w=2*pi*n./T; j}F;Bfq!  
g=-i*ww./2;                    % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T *vS)aRK  
L=4;                           % length of evoluation to compare with S. Trillo's paper j3$\+<m]  
dz=L/M1;                       % space step, make sure nonlinear<0.05 a*3h|b<  
for m1 = 1:1:M1                                    % Start space evolution zAA3bgaa  
   u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1;          % 1st sSolve nonlinear part of NLS %'
3Y?d  
   u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2; y=k!>Y|E  
   ca1 = fftshift(fft(u1));                        % Take Fourier transform |-zefzD|  
   ca2 = fftshift(fft(u2)); mzH3Q564  
   c2=exp(g.*dz).*(ca2+i*1*ca1.*dz);               % approximation <)4>"SN&^  
   c1=exp(g.*dz).*(ca1+i*1*ca2.*dz);               % frequency domain phase shift   ^3 6oqe{  
   u2 = ifft(fftshift(c2));                        % Return to physical space ;>jLRx<KC  
   u1 = ifft(fftshift(c1)); +h?Rb3=S  
if rem(m1,J) == 0                                 % Save output every J steps. %&\DCAFk  
    U1 = [U1 u1];                                  % put solutions in U array N&YQZ^o  
    U2=[U2 u2]; d