计算脉冲在非线性耦合器中演化的Matlab 程序 /f~ V(DK V^B' T]s % This Matlab script file solves the coupled nonlinear Schrodinger equations of
z #c)Q % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
<\!+J\YTA % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
%>`0hk88 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
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+Wh0Of %fid=fopen('e21.dat','w');
|0:< Z( N = 128; % Number of Fourier modes (Time domain sampling points)
D@*<p h= M1 =3000; % Total number of space steps
5jD2%"YUV J =100; % Steps between output of space
s <Pk[7`* T =10; % length of time windows:T*T0
Bm2" } = T0=0.1; % input pulse width
qFp } + s MN1=0; % initial value for the space output location
r7o63] dt = T/N; % time step
8X!^ 2B}J n = [-N/2:1:N/2-1]'; % Index
KZUB{Y^) t = n.*dt;
_Z z" ` u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
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p> R8 u20=u10.*0.0; % input to waveguide 2
/{
Lo0 u1=u10; u2=u20;
`V Y -3 U1 = u1;
}D/0& <1 U2 = u2; % Compute initial condition; save it in U
.P+om<~B ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
J[2c[|[- w=2*pi*n./T;
v?BX 4FO g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
3Xyu`zS& L=4; % length of evoluation to compare with S. Trillo's paper
)w_0lm'v{r dz=L/M1; % space step, make sure nonlinear<0.05
Gh}sk-Xk= for m1 = 1:1:M1 % Start space evolution
.)~IoIW= u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
37Ux2t u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
Ae R3wua ca1 = fftshift(fft(u1)); % Take Fourier transform
y<jW 7GNt ca2 = fftshift(fft(u2));
:5IbOpVM c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
H+y(W5|2/X c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
&QFg = u2 = ifft(fftshift(c2)); % Return to physical space
aal5d_Y u1 = ifft(fftshift(c1));
oV"#1 lp* if rem(m1,J) == 0 % Save output every J steps.
Uu
~BErEC U1 = [U1 u1]; % put solutions in U array
6 =A U2=[U2 u2];
H"lq!C` MN1=[MN1 m1];
rKg~H=4x2 z1=dz*MN1'; % output location
gB b+Q, end
89ivyv;]U end
E+-ah vk hg=abs(U1').*abs(U1'); % for data write to excel
%_C!3kKv ~ ha=[z1 hg]; % for data write to excel
GyQu?` t1=[0 t'];
_tDSG] hh=[t1' ha']; % for data write to excel file
6qg_&woJ3 %dlmwrite('aa',hh,'\t'); % save data in the excel format
l2Z!;Wm( figure(1)
21i ?$ uU waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
fvnj:3RK figure(2)
w6 0I;.hy waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
H:byCFN- at"-X ?`d 非线性超快脉冲耦合的数值方法的Matlab程序 YLs%u=e($ T pXbJ]o9 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。
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7 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
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Ve\^(9n {`~uBz+dJq <Vucr % This Matlab script file solves the nonlinear Schrodinger equations
%GS^=Qr % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
s/#L?[YH % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
B^Y AKbY % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
2;X{ZLo k$]- fQM C=1;
('k ;Ikut M1=120, % integer for amplitude
n<RvL^T=
M3=5000; % integer for length of coupler
=(\
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0-[ N = 512; % Number of Fourier modes (Time domain sampling points)
'MZX"t dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
Q'-g+aN T =40; % length of time:T*T0.
~1e?9D dt = T/N; % time step
(
-^- n = [-N/2:1:N/2-1]'; % Index
XIQfgrGZ t = n.*dt;
Si=zxy T ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
0'&N?rS w=2*pi*n./T;
n:QFwwQ`Q; g1=-i*ww./2;
]6JI(( g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
'u"r ^o? g3=-i*ww./2;
cTlitf9 P1=0;
|VC|@ Q P2=0;
G&ZpQ) P3=1;
m"3gTqG P=0;
2e~ud9, for m1=1:M1
2Lravb3 p=0.032*m1; %input amplitude
up`.#GWm s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
:
&! >.Y s1=s10;
< zUU` s20=0.*s10; %input in waveguide 2
-<e8\ Z` s30=0.*s10; %input in waveguide 3
oqM(?3 yv s2=s20;
Py?EA*(d# s3=s30;
!l2=J/LJj p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
Wp5w}8g %energy in waveguide 1
B?o ?LI p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
*WS'C}T %energy in waveguide 2
> wsS75n1 p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
{|cuu"j 26 %energy in waveguide 3
^uZ!e+ for m3 = 1:1:M3 % Start space evolution
&dA{ <. s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
x.gRTR`7( s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
8Ter]0M& s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
/ eFudMl sca1 = fftshift(fft(s1)); % Take Fourier transform
<hG ] f% sca2 = fftshift(fft(s2));
Y"eR&d sca3 = fftshift(fft(s3));
?r< F/$/ sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
gie.K1@| sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
aX`@WXK sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
H~fX >6> s3 = ifft(fftshift(sc3));
lawjGI s2 = ifft(fftshift(sc2)); % Return to physical space
bBwMx{iNNz s1 = ifft(fftshift(sc1));
Ed&;d+NM end
kd0~@rPL p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
Z]Zs"$q@ p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
z>n<+tso p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
i,k.#Vx[m P1=[P1 p1/p10];
cSMiNR P2=[P2 p2/p10];
I,rs&m?/m P3=[P3 p3/p10];
Glz yFj P=[P p*p];
^Ob#B!= end
a 04I.5! figure(1)
8Xo`S<8VS plot(P,P1, P,P2, P,P3);
!%v=9muay 8[2.HM$Y 转自：
http://blog.163.com/opto_wang/
