计算脉冲在非线性耦合器中演化的Matlab 程序 _ak.G= "bL P3 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
lrM.RM96 % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
X+fu hcn % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
hn*}5!^ % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
3ZLr"O1l ) d91I %fid=fopen('e21.dat','w');
/2=_B4E2 N = 128; % Number of Fourier modes (Time domain sampling points)
qFB9,cUqh M1 =3000; % Total number of space steps
aU ,0gvI(} J =100; % Steps between output of space
}mkA Hmu4 T =10; % length of time windows:T*T0
i G?w; T0=0.1; % input pulse width
$@XPL~4 MN1=0; % initial value for the space output location
bL6L- S dt = T/N; % time step
`\4 RFr$ n = [-N/2:1:N/2-1]'; % Index
;F"
kD t = n.*dt;
$yP'k&b! u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
? Yynd u20=u10.*0.0; % input to waveguide 2
\k2C 5f u1=u10; u2=u20;
vY8 WqG] U1 = u1;
My`josJ`Pb U2 = u2; % Compute initial condition; save it in U
^R&_}bp ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
h Kp,4D>2_ w=2*pi*n./T;
A ?%XO
% g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
'M]CZ } L=4; % length of evoluation to compare with S. Trillo's paper
AI IBd dz=L/M1; % space step, make sure nonlinear<0.05
o +PQ;Dl for m1 = 1:1:M1 % Start space evolution
<ls i.x\y< u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
VuYWb)@ u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
U)IsTk~}O ca1 = fftshift(fft(u1)); % Take Fourier transform
A,-[/Z K/ ca2 = fftshift(fft(u2));
8Iqk%n~( c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
_"Fbj Q" c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
M9ter& u2 = ifft(fftshift(c2)); % Return to physical space
?(|TP^ u1 = ifft(fftshift(c1));
FcJ.)U if rem(m1,J) == 0 % Save output every J steps.
M4L~bK U1 = [U1 u1]; % put solutions in U array
.~V".tZV[ U2=[U2 u2];
,_e/a MN1=[MN1 m1];
~Sn5;g8+\ z1=dz*MN1'; % output location
Cz$H k;3\6 end
[ 5}cU{M end
MfZ}xu hg=abs(U1').*abs(U1'); % for data write to excel
-Lz1#S k]A ha=[z1 hg]; % for data write to excel
ys~p( t1=[0 t'];
PG-cu$\?? hh=[t1' ha']; % for data write to excel file
!$ J ) %dlmwrite('aa',hh,'\t'); % save data in the excel format
<7sF<KD figure(1)
q^T&A[hMPx waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
t6H2t P\AS figure(2)
7oqn;6<[>, waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
sbq44L) R+@sHsZ@ 非线性超快脉冲耦合的数值方法的Matlab程序 i85+p2i7 HC<BGIgL 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。
[h 2p8i 'o 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
HCe-]nMd 3qV>TE]6, l yLK$B?/ 2C
8L\ % This Matlab script file solves the nonlinear Schrodinger equations
S3Jyg N* % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
+2_6C;_DX % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
6{F S /+ % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
ADwwiq #E ` )gkkZ$)j C=1;
'8kL1 M1=120, % integer for amplitude
Br. $L M3=5000; % integer for length of coupler
R;Ix<y{U N = 512; % Number of Fourier modes (Time domain sampling points)
2=UTH% 1D dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
;MdK 3c T =40; % length of time:T*T0.
/n<Ncf dt = T/N; % time step
@Tm0T7C n = [-N/2:1:N/2-1]'; % Index
=:R[gdA#1 t = n.*dt;
}1^ tK(Am ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Kw5+4R(5 w=2*pi*n./T;
O<H@:W #k g1=-i*ww./2;
m= beB\= g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
N%M>,wT g3=-i*ww./2;
1H2u,{O P1=0;
.tHv4.ob P2=0;
d9e H}#OY P3=1;
ju 2X* P=0;
"
:nVigw& for m1=1:M1
;] `NR p=0.032*m1; %input amplitude
vng8{Mx90* s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
AQBx
k[ s1=s10;
b3HTCO-,fC s20=0.*s10; %input in waveguide 2
#.t$A9' s30=0.*s10; %input in waveguide 3
G4`sRa T. s2=s20;
YaE['a s3=s30;
<x h'@592 p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
+
1%^c (3 %energy in waveguide 1
HDXjH|of p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
V~^6 TS( %energy in waveguide 2
# }]il0d p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
Zo63 8*32 %energy in waveguide 3
h/y} for m3 = 1:1:M3 % Start space evolution
BrH`:Dw s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
`? S?)0B s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
. L6@Rs s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
]e3}9. sca1 = fftshift(fft(s1)); % Take Fourier transform
moM&2rgdrQ sca2 = fftshift(fft(s2));
(j 8,n<o sca3 = fftshift(fft(s3));
v(nQd6;T sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
7 J_f/st sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
LyPBFo[? sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
#d i_V" s3 = ifft(fftshift(sc3));
~ X(xa s2 = ifft(fftshift(sc2)); % Return to physical space
kAF}*&Kzd~ s1 = ifft(fftshift(sc1));
B c@r*zb end
W2LblZE! p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
EQ`t:jc { p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
Y GO 7lar p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
5$G??="K P1=[P1 p1/p10];
T|iF/p]F P2=[P2 p2/p10];
JGNxJ S<] P3=[P3 p3/p10];
0*M}QXt P=[P p*p];
umn~hb5O end
qO3BQ]UF figure(1)
1kw4'#J8 plot(P,P1, P,P2, P,P3);
U$JIF/MO_ ^ {+:w:g 转自：
http://blog.163.com/opto_wang/
