计算脉冲在非线性耦合器中演化的Matlab 程序 P;>!wU~ * /t5g"n3 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
xpz`))w % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
_rG-#BKW8L % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
P 4H*j y@? % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
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L %fid=fopen('e21.dat','w');
n }TTq6B N = 128; % Number of Fourier modes (Time domain sampling points)
Bd QQ9$@5 M1 =3000; % Total number of space steps
eA10xp M0 J =100; % Steps between output of space
[e1\ A&T T =10; % length of time windows:T*T0
pj j}K T0=0.1; % input pulse width
ym[+Rw MN1=0; % initial value for the space output location
O2$! '!hz dt = T/N; % time step
[ (!Q- 8 n = [-N/2:1:N/2-1]'; % Index
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t = n.*dt;
ItMl4P`| u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
R:BBF9sK? u20=u10.*0.0; % input to waveguide 2
EJv! tyJ\[ u1=u10; u2=u20;
d {?)q U1 = u1;
0: HC;J U2 = u2; % Compute initial condition; save it in U
;g6 nHek ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Hc>([?P%t w=2*pi*n./T;
E=A/4p6\$ g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
+<H !3sW L=4; % length of evoluation to compare with S. Trillo's paper
Mi<*6j0 dz=L/M1; % space step, make sure nonlinear<0.05
KqFmFcf| for m1 = 1:1:M1 % Start space evolution
@f-0X1C."N u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
/Ql6]8.P u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
Q z'O {f ca1 = fftshift(fft(u1)); % Take Fourier transform
h=:*7>} ca2 = fftshift(fft(u2));
<.: 5Vx(Aw c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
9'D8[p% c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
ozT._ C u2 = ifft(fftshift(c2)); % Return to physical space
XL= 2wh u1 = ifft(fftshift(c1));
hcj{%^p if rem(m1,J) == 0 % Save output every J steps.
twAw01". U1 = [U1 u1]; % put solutions in U array
n}) U2=[U2 u2];
C zK%x?~] MN1=[MN1 m1];
?exALv'B z1=dz*MN1'; % output location
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.oi3m end
Lqg7D\7j end
x/pC%25 hg=abs(U1').*abs(U1'); % for data write to excel
VOD1xWrb ha=[z1 hg]; % for data write to excel
9Y; }JVS t1=[0 t'];
Uy: @,DW hh=[t1' ha']; % for data write to excel file
no e b f %dlmwrite('aa',hh,'\t'); % save data in the excel format
^.nwc# figure(1)
h\Z3y AYd waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
=#7s+ d- figure(2)
JiG8jB7%} waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
B ASO$?jf4 M|5^ ':Y 非线性超快脉冲耦合的数值方法的Matlab程序 "#[o?_GaJ 4X<Oux* 在研究脉冲在非线性耦合器中的演变时，我们需要求解非线性偏微分方程组。在如下的
论文中，我们提出了一种简洁的数值方法。 这里我们提供给大家用Matlab编写的计算程序。
4KN0i Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
AEBw#v!,o h;&&@5@lM hj%}GP{{ bfcD5:q % This Matlab script file solves the nonlinear Schrodinger equations
h}Fu"zK % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
J+-,^8) % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
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% pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
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$ :/n
?4K^ C=1;
LX&=uv%-^ M1=120, % integer for amplitude
qg/Y;tGSx M3=5000; % integer for length of coupler
gEX:S(1 QP N = 512; % Number of Fourier modes (Time domain sampling points)
8Xt=eL/P dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
W+fkWq7`Xx T =40; % length of time:T*T0.
}s8*QfK> dt = T/N; % time step
Z3&XTsq n = [-N/2:1:N/2-1]'; % Index
M)bC%(xJ t = n.*dt;
',v0vyO8 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
3/]f4D{MMY w=2*pi*n./T;
X7(rg W 8 g1=-i*ww./2;
So3,Z'z= g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
F 5b]/;| g3=-i*ww./2;
^v ()iF
! P1=0;
aC
$h_ P2=0;
bYRQI=gW': P3=1;
4c493QOd P=0;
67EDkknt for m1=1:M1
*R1d4|/G p=0.032*m1; %input amplitude
nJnO/~| s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
^ ^U)WB s1=s10;
pJ<)intcbE s20=0.*s10; %input in waveguide 2
qCv}+d) s30=0.*s10; %input in waveguide 3
zXA= se0U s2=s20;
2l;ge>D J s3=s30;
QZe b+r p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
IW SEssP %energy in waveguide 1
&AkzSgP p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
vErbX3RY2 %energy in waveguide 2
_ ;v _L p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
-F~9f> %energy in waveguide 3
mAtG&my) for m3 = 1:1:M3 % Start space evolution
0.3[=a4 3 s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
"@):*3
4 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
60SenHKles s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
)xXrs^ sca1 = fftshift(fft(s1)); % Take Fourier transform
G+%5V5GS sca2 = fftshift(fft(s2));
jw& }N6^G sca3 = fftshift(fft(s3));
}sm56}_ sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
tF) k6*+ sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
uvAy#, sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
dh 7)N}2 s3 = ifft(fftshift(sc3));
n Y. Umj s2 = ifft(fftshift(sc2)); % Return to physical space
3vEjf s1 = ifft(fftshift(sc1));
5 }(YMsUb end
iKCTYXN1( p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
ff2.| 20 p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
omDi<- p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
0L
4]z'5 P1=[P1 p1/p10];
^~hhdwu3a P2=[P2 p2/p10];
x#!{5;V&K P3=[P3 p3/p10];
7~k~S>sO P=[P p*p];
7xa@wa?!L end
%d~9at6-B figure(1)
*~MiL 9m+? plot(P,P1, P,P2, P,P3);
A/W7 ;D 2v;
7ohK 转自：
http://blog.163.com/opto_wang/
