计算脉冲在非线性耦合器中演化的Matlab 程序 ^ H ThN X!Mx5fg % This Matlab script file solves the coupled nonlinear Schrodinger equations of
J^nBdofP % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
fk[ -mZ % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
ox>^>wR* % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
#A Sz;$P Y1OkkcPb{ %fid=fopen('e21.dat','w');
4 \K7xM! N = 128; % Number of Fourier modes (Time domain sampling points)
gA5/,wDO M1 =3000; % Total number of space steps
3yY}04[9< J =100; % Steps between output of space
D>@I+4{p T =10; % length of time windows:T*T0
tl4V7!U@^z T0=0.1; % input pulse width
YTX,cj#D^& MN1=0; % initial value for the space output location
1k5Who@ dt = T/N; % time step
.hP D$o n = [-N/2:1:N/2-1]'; % Index
,j}6?
Q t = n.*dt;
*_{j=sd u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
z^ q0/' u20=u10.*0.0; % input to waveguide 2
VT%NO'0 u1=u10; u2=u20;
o \<ULW* U1 = u1;
OwUhdiG U2 = u2; % Compute initial condition; save it in U
,I$`-$_' ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
vNY{j7l/W w=2*pi*n./T;
[f-?y mmT g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
9ni1f {k L=4; % length of evoluation to compare with S. Trillo's paper
gX}8#O.K$ dz=L/M1; % space step, make sure nonlinear<0.05
r
CHl?J for m1 = 1:1:M1 % Start space evolution
3cyHfpx-W u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
?|C2*?hZ+ u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
#m<nAR ca1 = fftshift(fft(u1)); % Take Fourier transform
| y#
Jx ca2 = fftshift(fft(u2));
vnt%XU,,Y c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
q u6D 5t c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
cAqLE\h u2 = ifft(fftshift(c2)); % Return to physical space
{G0T$,'DR u1 = ifft(fftshift(c1));
eKLZt%= if rem(m1,J) == 0 % Save output every J steps.
V/LLaZ TE U1 = [U1 u1]; % put solutions in U array
9y8&9<# U2=[U2 u2];
O67W&nz MN1=[MN1 m1];
<X^@*79m z1=dz*MN1'; % output location
4qbBc1,7y end
4*#18<u5 end
UWJ8a mA hg=abs(U1').*abs(U1'); % for data write to excel
B =T'5& ha=[z1 hg]; % for data write to excel
|t&>5HM t1=[0 t'];
S_4?K)n # hh=[t1' ha']; % for data write to excel file
Ugt/rf 5n %dlmwrite('aa',hh,'\t'); % save data in the excel format
VUGmi]qd figure(1)
_|\~q[ep waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
\?ZB]*Fu figure(2)
|A9F\A->4 waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
wn, KY$/ !r8 `Yr n 非线性超快脉冲耦合的数值方法的Matlab程序 ~i{(<.he $q{!5-e 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。
*NaB#;+|k` 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
&|ex`nwc 0 Jbg/0|1 t?&|8SId 0 [#
3;a % This Matlab script file solves the nonlinear Schrodinger equations
7 \[@ m3s % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
1;8UC;, % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
vjCu4+w($Z % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
SrJGTuXg HT S0s\R$ C=1;
|\t-g" ~sN M1=120, % integer for amplitude
*?>T,g x} M3=5000; % integer for length of coupler
[`[ |l
N = 512; % Number of Fourier modes (Time domain sampling points)
uEP*iPLD@ dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
Tc:)-
z[o T =40; % length of time:T*T0.
mh #a#< dt = T/N; % time step
A#<? 4& n = [-N/2:1:N/2-1]'; % Index
.},'~NM] t = n.*dt;
>J?fl8 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
eA ? RK.e w=2*pi*n./T;
>dD@j:Qc g1=-i*ww./2;
$G+@_' g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
^|>PA:% g3=-i*ww./2;
X-Kh(Z P1=0;
~&{S<Wl P2=0;
RJ&RTo P3=1;
@%uUiP0 P=0;
(gU!=F?#m for m1=1:M1
NB#OCH1/9 p=0.032*m1; %input amplitude
g2ixx+`?|: s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
k5e;fA/w s1=s10;
hEH?[>9 s20=0.*s10; %input in waveguide 2
L}b.ulkMD s30=0.*s10; %input in waveguide 3
5m 4P\y^a s2=s20;
{duz\k2 s3=s30;
3M7/?TMw{6 p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
i)#d WFDTv %energy in waveguide 1
n'Lr QU p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
q:0N<$63 %energy in waveguide 2
KY I / p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
o[w:1q7 %energy in waveguide 3
HM1Fz\Sf for m3 = 1:1:M3 % Start space evolution
~jk|4`I?T s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
p)-^;=<B3 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
p27~>xQ s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
ZJJY8k ` sca1 = fftshift(fft(s1)); % Take Fourier transform
..5CC;B sca2 = fftshift(fft(s2));
f~R(D0 @ sca3 = fftshift(fft(s3));
tSUEZ62EY sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
^
VyKd sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
exUFS5d sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
[ l??A3G s3 = ifft(fftshift(sc3));
B d fwa s2 = ifft(fftshift(sc2)); % Return to physical space
MJO-q $)c s1 = ifft(fftshift(sc1));
@b%=H/5\ end
4k1xy## p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
yx[/|nZDC4 p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
Qd{CMm x p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
AV]2 euyn P1=[P1 p1/p10];
U< fGGCw P2=[P2 p2/p10];
ec;o\erPG P3=[P3 p3/p10];
cqkV9f8Ro P=[P p*p];
4F: \-O end
+3BN } figure(1)
`/+>a8 plot(P,P1, P,P2, P,P3);
};zFJ6I8 Gb6 'n$g 转自：
http://blog.163.com/opto_wang/
