计算脉冲在非线性耦合器中演化的Matlab 程序 ybYXD? X|)Il8 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
jrcc % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
Ou!)1UFI % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
kPedX % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
%IU 4\ZY> `D"1
gD}{A %fid=fopen('e21.dat','w');
](n69XX_ N = 128; % Number of Fourier modes (Time domain sampling points)
(zEYpTp M1 =3000; % Total number of space steps
GZ,j?@ J =100; % Steps between output of space
w= B T =10; % length of time windows:T*T0
tnJ`D 4 T0=0.1; % input pulse width
c}'Xoc MN1=0; % initial value for the space output location
.S(^roM;+ dt = T/N; % time step
v C-[#]< n = [-N/2:1:N/2-1]'; % Index
Crg#6k1~EN t = n.*dt;
%|bN@@ u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
o[imNy~ ~ u20=u10.*0.0; % input to waveguide 2
#'KY`&Tw& u1=u10; u2=u20;
wRj~Qv~E U1 = u1;
l`qP~ k# U2 = u2; % Compute initial condition; save it in U
]%||KC!O ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Y` q!V= w=2*pi*n./T;
xpz`))w g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
_rG-#BKW8L L=4; % length of evoluation to compare with S. Trillo's paper
P 4H*j y@? dz=L/M1; % space step, make sure nonlinear<0.05
W QTendS for m1 = 1:1:M1 % Start space evolution
A` =]RJ u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
b sMC#xT u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
nE^wxtY ca1 = fftshift(fft(u1)); % Take Fourier transform
C~:b* X ca2 = fftshift(fft(u2));
cS5w +`,L c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
vg5E/+4gp% c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
O${r^6Hh u2 = ifft(fftshift(c2)); % Return to physical space
#'#4hJ*YC u1 = ifft(fftshift(c1));
HoMQt3C if rem(m1,J) == 0 % Save output every J steps.
\2(MpB\_6! U1 = [U1 u1]; % put solutions in U array
A?\h|u< U2=[U2 u2];
"3v7 gtGG MN1=[MN1 m1];
0NVG"-Q z1=dz*MN1'; % output location
1RURZoL end
>Zi|$@7t- end
4;08n|C hg=abs(U1').*abs(U1'); % for data write to excel
Qh /lT$g ha=[z1 hg]; % for data write to excel
:m)c[q8 t1=[0 t'];
X5|?/aR} hh=[t1' ha']; % for data write to excel file
" pR $cS %dlmwrite('aa',hh,'\t'); % save data in the excel format
_CHKh*KHML figure(1)
5/* )+ waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
[''=>< figure(2)
(
?atGFgu waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
rD_Ss.\^g D
"JMSL4r 非线性超快脉冲耦合的数值方法的Matlab程序 Z?5,cI[6# T@2f&Un^ 在研究脉冲在非线性耦合器中的演变时，我们需要求解非线性偏微分方程组。在如下的
论文中，我们提出了一种简洁的数值方法。 这里我们提供给大家用Matlab编写的计算程序。
^Z#<tN; Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
SZNFE 3 t~X: pIk4V/ fy s9^"wN YQ % This Matlab script file solves the nonlinear Schrodinger equations
T[`QO`\5O % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
0 ;. e#(`- % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
aMe%#cLI % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
PG C07U :B Yk( NZ3O C=1;
K +(m'3` M1=120, % integer for amplitude
y}s
0J K M3=5000; % integer for length of coupler
eW<!^Aer N = 512; % Number of Fourier modes (Time domain sampling points)
0tn7Rkiw dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
7N&3FER T =40; % length of time:T*T0.
pmE1EDPag dt = T/N; % time step
qdg= Imx n = [-N/2:1:N/2-1]'; % Index
5<0Yh#_ t = n.*dt;
zW|$x<M^ ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
g;|
n8] w=2*pi*n./T;
T#ecLD# g1=-i*ww./2;
vq@#Be?@
g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
h9@gs,' g3=-i*ww./2;
-K{\S2 P1=0;
M}_M_ P2=0;
D|
3AjzW P3=1;
p1[WGeV P=0;
\J#I}-a&j for m1=1:M1
F!DrZd>\ p=0.032*m1; %input amplitude
FuRn%)DA5 s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
r-Xjy *T s1=s10;
@pyA;>U s20=0.*s10; %input in waveguide 2
cHfK- R s30=0.*s10; %input in waveguide 3
?Vb=4B{~ s2=s20;
U^WQW a s3=s30;
ePFC$ kMn p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
GcU(:V2o %energy in waveguide 1
tFb|y+ p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
TU^tW %energy in waveguide 2
(5CX *)R p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
yDl5t-0` %energy in waveguide 3
3M5=@Fwkr for m3 = 1:1:M3 % Start space evolution
y2 d_b/ s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
l a6 e` s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
Xqq?S s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
@idp8J [td sca1 = fftshift(fft(s1)); % Take Fourier transform
oWn_3gzw; sca2 = fftshift(fft(s2));
W"DxIy sca3 = fftshift(fft(s3));
oD|+X/F K sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
m''i E sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
*8(t y%5F0 sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
X]f#w s3 = ifft(fftshift(sc3));
\p_8YC s2 = ifft(fftshift(sc2)); % Return to physical space
`^@g2c+d s1 = ifft(fftshift(sc1));
A*?/F:E end
&vGEz*F p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
KH CdO p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
vFkyfX( p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
%QlBFl0a P1=[P1 p1/p10];
|R| U z` P2=[P2 p2/p10];
Y=# mx3. P3=[P3 p3/p10];
~vvQz" P=[P p*p];
(*@~HF,t= end
7kew/8- figure(1)
& dHm!b plot(P,P1, P,P2, P,P3);
pu
m9x)y1 )l81R 转自：
http://blog.163.com/opto_wang/
