计算脉冲在非线性耦合器中演化的Matlab 程序 bm ddh2 A><%"9p Z % This Matlab script file solves the coupled nonlinear Schrodinger equations of
Ox43(S0~ % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
uTJ?@ ^nq % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
$S cjEG:6 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
#6m//0 u O "h+i>|l %fid=fopen('e21.dat','w');
h/w- &7t N = 128; % Number of Fourier modes (Time domain sampling points)
I~T?tm M1 =3000; % Total number of space steps
nocH~bAf2 J =100; % Steps between output of space
KJkcmF}Q T =10; % length of time windows:T*T0
F RF}V@~ T0=0.1; % input pulse width
rC*n Z* MN1=0; % initial value for the space output location
4-n.4j| dt = T/N; % time step
3 \WdA$Wx n = [-N/2:1:N/2-1]'; % Index
;~q)^.K3 t = n.*dt;
NA ocmbfNz u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
^e 6(#SqR u20=u10.*0.0; % input to waveguide 2
ohyUvxvj u1=u10; u2=u20;
,^ ,J[F U1 = u1;
mLYB6 U2 = u2; % Compute initial condition; save it in U
lJ,s}l7 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
|Z/ySAFM w=2*pi*n./T;
-T(V6 &'Qi g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
gR>#LM&dG L=4; % length of evoluation to compare with S. Trillo's paper
@<sP1`1 dz=L/M1; % space step, make sure nonlinear<0.05
V7v,)a" L for m1 = 1:1:M1 % Start space evolution
Bms?`7}N u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
\%VoX` B u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
Y{'G2) e ca1 = fftshift(fft(u1)); % Take Fourier transform
Kj>_XaFCg! ca2 = fftshift(fft(u2));
gy[uq m_ T c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
}R'oAE}$ c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
)G|U B8] u2 = ifft(fftshift(c2)); % Return to physical space
ljCgIfZ_4 u1 = ifft(fftshift(c1));
n(+:l'#HJ if rem(m1,J) == 0 % Save output every J steps.
ZtT`_G& U1 = [U1 u1]; % put solutions in U array
rYqvG U2=[U2 u2];
Y#5S;?bR MN1=[MN1 m1];
Q&LkST-i z1=dz*MN1'; % output location
<Jk|Bmw; end
_B[(/wY end
Z~g qTB]H hg=abs(U1').*abs(U1'); % for data write to excel
m4
(Fuu ha=[z1 hg]; % for data write to excel
U#P#YpD;== t1=[0 t'];
3N21[i2/m hh=[t1' ha']; % for data write to excel file
M>#{~zr %dlmwrite('aa',hh,'\t'); % save data in the excel format
h^)2:0#{I figure(1)
o_5@R+& waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
U|QDV16f figure(2)
-d~'tti waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
WveFB%@`; "8I4]' 非线性超快脉冲耦合的数值方法的Matlab程序 !]nCeo ( qrT0D6 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。
{ m?x}, 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
=EJ"edw]%0 )q IK7; (!(bysi9 FRW.
% This Matlab script file solves the nonlinear Schrodinger equations
$9 ~1s/(' % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
qG qu/$b h % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
;a` X|N9 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
>A/=eW/q #rwR)9iC0 C=1;
F8I <4S M1=120, % integer for amplitude
>>r:L3 <! M3=5000; % integer for length of coupler
`dZ| }4[1 N = 512; % Number of Fourier modes (Time domain sampling points)
$%-?S ]6) dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
mI%/k7:sf T =40; % length of time:T*T0.
-Me\nu8(RF dt = T/N; % time step
p3 o?_ !Z n = [-N/2:1:N/2-1]'; % Index
._Xtb,p{ t = n.*dt;
v2' J L(= ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
gib]#n1!p w=2*pi*n./T;
'Ap 5Aq g1=-i*ww./2;
%U 7B0- g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
@gc"- V*-/ g3=-i*ww./2;
Vvj]2V3 P1=0;
Tjqn::~D P2=0;
%K7}yy&9C P3=1;
h~p}08 P=0;
?s]`G'=>V` for m1=1:M1
=.a ]?&Yyh p=0.032*m1; %input amplitude
O@rb4( s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
`9l\ ~t(M
s1=s10;
KF)i6 6 s20=0.*s10; %input in waveguide 2
,GIqRT4K s30=0.*s10; %input in waveguide 3
&?6w 2[} s2=s20;
t,,^^ll s3=s30;
mtHz6+ p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
~~,<+X: %energy in waveguide 1
)[*O^bPowI p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
k Dt)S$N4n %energy in waveguide 2
ex458^N_ p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
}q W a E %energy in waveguide 3
beE % %C]X for m3 = 1:1:M3 % Start space evolution
/ GUuu s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
wlM
?gQXU[ s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
8)8oR&(f s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
p%1m&/ `F sca1 = fftshift(fft(s1)); % Take Fourier transform
(q N(#~ sca2 = fftshift(fft(s2));
qGCg3u6 sca3 = fftshift(fft(s3));
;7k7/f : sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
4
G[hU4L sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
[Gy'0P(EQ sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
zP}v2 s3 = ifft(fftshift(sc3));
N-E`go s2 = ifft(fftshift(sc2)); % Return to physical space
c&-$?f
r s1 = ifft(fftshift(sc1));
{W<-f? end
Ai 18]QD- p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
6~W E #z_ p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
wf%Ep#^6} p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
%)Dd{|c P1=[P1 p1/p10];
@0,dyg<$> P2=[P2 p2/p10];
cV,Dl`1r P3=[P3 p3/p10];
q)+ n2FM P=[P p*p];
uTGvXKL7 end
WI_mJ/2 figure(1)
%0]b5u plot(P,P1, P,P2, P,P3);
`|Z@UPHzG JSK5x(GlH 转自：
http://blog.163.com/opto_wang/
