计算脉冲在非线性耦合器中演化的Matlab 程序 :?#cDyW) hht+bpHl % This Matlab script file solves the coupled nonlinear Schrodinger equations of
(`mOB6j % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
v=Mz I#0L % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
5KaSWw/ % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
R=86w_ C->[$HcRa %fid=fopen('e21.dat','w');
8Mb$+^ zU N = 128; % Number of Fourier modes (Time domain sampling points)
q]l\`/R%u M1 =3000; % Total number of space steps
V=9Bto00 J =100; % Steps between output of space
Eq7gcDQ T =10; % length of time windows:T*T0
h@Dw'w T0=0.1; % input pulse width
1gAc, s2 MN1=0; % initial value for the space output location
g T D%4V dt = T/N; % time step
YiNo#M91 n = [-N/2:1:N/2-1]'; % Index
vGyppm[0 t = n.*dt;
Tvrc%L(] u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
c}\
d5R_ L u20=u10.*0.0; % input to waveguide 2
%w@ig ~vD' u1=u10; u2=u20;
2dyxKK!\a U1 = u1;
%Fm`Y .l U2 = u2; % Compute initial condition; save it in U
hhj
,rcsi ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
)SD_}BY%k w=2*pi*n./T;
8fEAYRGd g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
W7] mfy^ L=4; % length of evoluation to compare with S. Trillo's paper
dcR6KG 8 dz=L/M1; % space step, make sure nonlinear<0.05
3]7ipwF2q for m1 = 1:1:M1 % Start space evolution
h %|9]5(= u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
(ai72#nFtb u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
cnYYs d{ ca1 = fftshift(fft(u1)); % Take Fourier transform
E =
^-Z ca2 = fftshift(fft(u2));
"mG!L$ c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
8 ZzU^x c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
9Mut p4# u2 = ifft(fftshift(c2)); % Return to physical space
@OrXbG7&># u1 = ifft(fftshift(c1));
B~e7w 4 if rem(m1,J) == 0 % Save output every J steps.
uRs9}dzv U1 = [U1 u1]; % put solutions in U array
_"`uqW79 U2=[U2 u2];
/$<JCN Gv MN1=[MN1 m1];
v.]'%+::# z1=dz*MN1'; % output location
H|x k${R` end
0sY#MHPT& end
xQZ MCd hg=abs(U1').*abs(U1'); % for data write to excel
J$<:/^t ha=[z1 hg]; % for data write to excel
s+Cl t1=[0 t'];
8L@UB6b\ hh=[t1' ha']; % for data write to excel file
64;oB_ %dlmwrite('aa',hh,'\t'); % save data in the excel format
dUUPhk0 figure(1)
Q=MCMe waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
dcM+ylB figure(2)
*%z<P~} waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
J>/Ci\OB m|(I} |kT3 非线性超快脉冲耦合的数值方法的Matlab程序 )m oo?Q +q 4W0 在研究脉冲在非线性耦合器中的演变时，我们需要求解非线性偏微分方程组。在如下的
论文中，我们提出了一种简洁的数值方法。 这里我们提供给大家用Matlab编写的计算程序。
{lTR/ Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
#r-j.f}yx @m } rQT ysQEJm^|-u
zd.1 % This Matlab script file solves the nonlinear Schrodinger equations
wV]sGHu F} % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
2OA8
R} % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
XtnIK % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
aEV|>K=6Y' vK[ v
eFH C=1;
WX+< 4j M1=120, % integer for amplitude
EXv\FUzo M3=5000; % integer for length of coupler
{^2({A#& N = 512; % Number of Fourier modes (Time domain sampling points)
1"*Nb5s dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
N}eU.#L T =40; % length of time:T*T0.
E5v|SFD dt = T/N; % time step
#J'Z5)i| n = [-N/2:1:N/2-1]'; % Index
|% la t = n.*dt;
6C@0[Q\ER ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
*8pe<:A#p w=2*pi*n./T;
KzxW?Ji$S g1=-i*ww./2;
H@ 1[SKBl g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
Q-H =wJ4R g3=-i*ww./2;
Q u,)wfp~ P1=0;
Cnb[t[hk+j P2=0;
* q\HFI P3=1;
L|dab {9 P=0;
'd~, o[x for m1=1:M1
znGZULa# p=0.032*m1; %input amplitude
3D[:Rf[ s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
<yX@@8 s1=s10;
A`+(VzZgJ s20=0.*s10; %input in waveguide 2
NzwGc+\7} s30=0.*s10; %input in waveguide 3
D 0,om l s2=s20;
64IeCAMVo s3=s30;
{H~8'K- p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
H >@JfYZ0 %energy in waveguide 1
>TH- Q [ p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
q70YNk} %energy in waveguide 2
\&l*e p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
#b<lt'gC %energy in waveguide 3
;$k ?&nhY for m3 = 1:1:M3 % Start space evolution
(STWAwK- s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
z[<pi : s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
AVdd?Ew s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
#I*ht0++ sca1 = fftshift(fft(s1)); % Take Fourier transform
oe RYyJ sca2 = fftshift(fft(s2));
J$e Z Lj sca3 = fftshift(fft(s3));
ocDVCCkxg sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
=~(L JPo6 sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
ijR*5#5h sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
%te'J G< s3 = ifft(fftshift(sc3));
Is#v6:#^ s2 = ifft(fftshift(sc2)); % Return to physical space
WZDokS R s1 = ifft(fftshift(sc1));
k[^}ld[ end
yx`r;|ds} p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
8B% O%*5` p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
h P6fTZ=Ln p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
P(W \aLp P1=[P1 p1/p10];
`G:qtHn"Q< P2=[P2 p2/p10];
Fg}5V, P3=[P3 p3/p10];
Td=] tVM P=[P p*p];
]pucv! end
FC/>L figure(1)
IhFw {=2* plot(P,P1, P,P2, P,P3);
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KoA[UJ G~mB =] 转自：
http://blog.163.com/opto_wang/
