计算脉冲在非线性耦合器中演化的Matlab 程序 B9_0 Yq YJ5;a\QxN % This Matlab script file solves the coupled nonlinear Schrodinger equations of
o^Y'e+T" % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
mP)<;gm, % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
$Q:5KNF+p % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
^/Hj^4 ~_U .~5cNu'#m %fid=fopen('e21.dat','w');
e;=G|E N = 128; % Number of Fourier modes (Time domain sampling points)
Hc@ Z7eQ3^ M1 =3000; % Total number of space steps
(WW,]#^
J =100; % Steps between output of space
t3/!es ay T =10; % length of time windows:T*T0
w? AE8n$8 T0=0.1; % input pulse width
Oh:SH|=]# MN1=0; % initial value for the space output location
>NE]TZ.F dt = T/N; % time step
'Ph4( Yg n = [-N/2:1:N/2-1]'; % Index
iR#jBqXD t = n.*dt;
Y5 4*mn u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
)^!-Aj \x u20=u10.*0.0; % input to waveguide 2
=* 'X u1=u10; u2=u20;
0zpP$q$ U1 = u1;
}}qR~.[ U2 = u2; % Compute initial condition; save it in U
`bZ_=UAb ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
_<.R \rX& w=2*pi*n./T;
sI`i g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
|y%pP/;&! L=4; % length of evoluation to compare with S. Trillo's paper
zck)D^, aO dz=L/M1; % space step, make sure nonlinear<0.05
:;" 3k64 for m1 = 1:1:M1 % Start space evolution
!00%z u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
w H#k~`M u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
'q*1HNw Gp ca1 = fftshift(fft(u1)); % Take Fourier transform
NUL~zb ca2 = fftshift(fft(u2));
j )F~C8* c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
oRu S_X c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
c2"eq2'BS u2 = ifft(fftshift(c2)); % Return to physical space
]-.Q9cjc$q u1 = ifft(fftshift(c1));
zMrZ[ AU if rem(m1,J) == 0 % Save output every J steps.
33Mr9Doon U1 = [U1 u1]; % put solutions in U array
3F}d,aB
A U2=[U2 u2];
JsPuxu_ MN1=[MN1 m1];
{/7'uD\
H z1=dz*MN1'; % output location
.^kTb2$X end
uR"]w7= end
Q)a*bPz hg=abs(U1').*abs(U1'); % for data write to excel
<{-DYRiN ha=[z1 hg]; % for data write to excel
5o~Z> t1=[0 t'];
vJq`l3& hh=[t1' ha']; % for data write to excel file
"Pys3=h %dlmwrite('aa',hh,'\t'); % save data in the excel format
m@c2'*&Y figure(1)
`Ze fSmb waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
y6j TT% figure(2)
9J]LV'f7 waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
h}`< pq xD lC]loi7 非线性超快脉冲耦合的数值方法的Matlab程序 Nq~bO_-I &(. ZHF 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。
eB]ZnJ2^ = 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
mU& J,C rWvJ{ -% A`r&"i OKA f:utw T % This Matlab script file solves the nonlinear Schrodinger equations
(~#PzE : % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
"{0kg'fU % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
9Pb0Olh % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
q5RLIstQ\ R\+$^G}#6 C=1;
cA L u M1=120, % integer for amplitude
xjX5 PQu M3=5000; % integer for length of coupler
5g &'n N = 512; % Number of Fourier modes (Time domain sampling points)
Aio0++ r- dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
L]tyL) T =40; % length of time:T*T0.
uuC/F_ ='B dt = T/N; % time step
$Y4
Ao-@ n = [-N/2:1:N/2-1]'; % Index
[wOO)FjT t = n.*dt;
?QMs< ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
l;;:3: w=2*pi*n./T;
&`%C'KZ g1=-i*ww./2;
=Tj0dfO|" g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
-J6}7>4^8} g3=-i*ww./2;
4v ?S` w:6 P1=0;
eX$Biv1N P2=0;
F% |(pHk P3=1;
7:;V [/ P=0;
O ,; SA for m1=1:M1
Cv=0&S. p=0.032*m1; %input amplitude
qj/P4 *6E s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
:dj@i6 s1=s10;
#QB`'2)vw s20=0.*s10; %input in waveguide 2
}Ag2c; aaq s30=0.*s10; %input in waveguide 3
p*'?(o:= s2=s20;
w7W-=\Hvh s3=s30;
9!OpW:bR| p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
WgL! @g %energy in waveguide 1
:H87x?e[ p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
5u!cA4e" %energy in waveguide 2
5u8Sxfm", p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
Yk5kC 0B %energy in waveguide 3
XU54skN for m3 = 1:1:M3 % Start space evolution
R3<+z s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
$pKS['J0 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
!`Wu LhB` s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
f0uiNy(r$ sca1 = fftshift(fft(s1)); % Take Fourier transform
(+@.L7>m+t sca2 = fftshift(fft(s2));
&d2/F i+ sca3 = fftshift(fft(s3));
Psv!` K sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
"&ks 8 3 sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
E0|aI4S4 sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
BCj&z{5"7e s3 = ifft(fftshift(sc3));
(1o^Dn3 s2 = ifft(fftshift(sc2)); % Return to physical space
;Cy@TzO/| s1 = ifft(fftshift(sc1));
Mc6y 'w end
jL8zH p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
4j*}|@x p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
I5~D C p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
Q&J,"Vxw P1=[P1 p1/p10];
y/ FisX P2=[P2 p2/p10];
s6$3[9Vh&9 P3=[P3 p3/p10];
`#]\Wnp~y P=[P p*p];
Vh<`MS0X end
s5pY) 6) figure(1)
ymzm x$o= plot(P,P1, P,P2, P,P3);
:U 9R
1^}A |); >wV" 转自：
http://blog.163.com/opto_wang/
