计算脉冲在非线性耦合器中演化的Matlab 程序 D<2| &xaR S>oQ m % This Matlab script file solves the coupled nonlinear Schrodinger equations of
IW.~I,!x % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
aBO%qmtt % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
; *Cu >f7 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
u-a* fT mGmkeD' %fid=fopen('e21.dat','w');
Nuw_,-h N = 128; % Number of Fourier modes (Time domain sampling points)
2Rp5 E^s M1 =3000; % Total number of space steps
y0R5YCq\": J =100; % Steps between output of space
: _>/Yd7-& T =10; % length of time windows:T*T0
]~SOGAFW T0=0.1; % input pulse width
Q`dzn= MN1=0; % initial value for the space output location
P%6-W 5< dt = T/N; % time step
P2S$Dk_<\X n = [-N/2:1:N/2-1]'; % Index
p -=+i
t = n.*dt;
dX0"h5v1 u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
x*A_1_A u20=u10.*0.0; % input to waveguide 2
F~cvob{ u1=u10; u2=u20;
o1"MW>B,4 U1 = u1;
>!vb ;a! U2 = u2; % Compute initial condition; save it in U
{/x[" 2a1 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Q_b F^4gt w=2*pi*n./T;
RfMrGC^? g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
8jE6zS }m L=4; % length of evoluation to compare with S. Trillo's paper
?2b*F Qe dz=L/M1; % space step, make sure nonlinear<0.05
S[bFS7[ for m1 = 1:1:M1 % Start space evolution
_z<y]?q u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
l qO" u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
3@r_t|j ca1 = fftshift(fft(u1)); % Take Fourier transform
Kzw )Q ca2 = fftshift(fft(u2));
=U6%Wdth c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
l ;I)$=={= c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
U`D.cEMfH u2 = ifft(fftshift(c2)); % Return to physical space
7[wHNJ7)r u1 = ifft(fftshift(c1));
`3Gjj&c if rem(m1,J) == 0 % Save output every J steps.
6]%79?'A U1 = [U1 u1]; % put solutions in U array
LV '@JFT- U2=[U2 u2];
LCrE1Q%VP MN1=[MN1 m1];
ydCVG," z1=dz*MN1'; % output location
8#gS{ end
S+Aq0B< end
wL'tGAv hg=abs(U1').*abs(U1'); % for data write to excel
[/}y!;3iXM ha=[z1 hg]; % for data write to excel
F F"6~ t1=[0 t'];
zW`$T 88~ hh=[t1' ha']; % for data write to excel file
*RQkL'tRf %dlmwrite('aa',hh,'\t'); % save data in the excel format
ps#+i figure(1)
gHLBtl/ waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
:>U2yI figure(2)
JfmNI~% waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
GbC-6 .~ L~yu 非线性超快脉冲耦合的数值方法的Matlab程序 !$"DD[~\ SCClD6k=V 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。
gWo `i 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
_`>F>aP ?j^[7 '/^bO# G: j +j2_\ % This Matlab script file solves the nonlinear Schrodinger equations
o#KGENd % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
/P*mF^Y % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
>^#OtFHuT) % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
ceakTA B[ -9XB.)\# C=1;
Lw
7,[?, Z M1=120, % integer for amplitude
i<N[s O M3=5000; % integer for length of coupler
pKf ]&?FX N = 512; % Number of Fourier modes (Time domain sampling points)
m>C}T dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
93="sS T =40; % length of time:T*T0.
V6.xp{[ dt = T/N; % time step
T~%}(0=m n = [-N/2:1:N/2-1]'; % Index
M{U {iS t = n.*dt;
wD}ojA&DU ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
<$#b3F"I w=2*pi*n./T;
P@ewr} g1=-i*ww./2;
,EyZ2` | g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
HS{a^c% g3=-i*ww./2;
bkQEfx. P1=0;
b[Z5:[@\# P2=0;
6#S}EaWf P3=1;
bi:m;R P=0;
gA)!1V+: for m1=1:M1
Y6T1_XG p=0.032*m1; %input amplitude
$sDvE~f0n s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
'j8 4-U{&) s1=s10;
1Ih.?7} s20=0.*s10; %input in waveguide 2
74VN3m s30=0.*s10; %input in waveguide 3
$vNz^!zgV s2=s20;
=VMV^[&> s3=s30;
l0Myem
v?z p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
y{h y %energy in waveguide 1
D8a[zXWnc p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
=%, ;=4w %energy in waveguide 2
0GR\iw$[J p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
zGrUl|j %energy in waveguide 3
ze!S4&B for m3 = 1:1:M3 % Start space evolution
t.sbfLu s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
i{8T 8 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
E DuLg g@ s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
ng]jpdeA sca1 = fftshift(fft(s1)); % Take Fourier transform
^dB~#A1 sca2 = fftshift(fft(s2));
I^iJ^Z]vx sca3 = fftshift(fft(s3));
d52l)8 sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
}."3&u't sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
?CB*MWjd sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
7^|oO~x6 s3 = ifft(fftshift(sc3));
[6@{^ s2 = ifft(fftshift(sc2)); % Return to physical space
/+\m7I S s1 = ifft(fftshift(sc1));
M_tY: v end
o]0v#2l' p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
pkjf5DWp p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
RZm}%6##ZC p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
t^0^He$Ot P1=[P1 p1/p10];
>
Y
<in / P2=[P2 p2/p10];
V[-4cu,Ph^ P3=[P3 p3/p10];
Mq-Q Wx"P P=[P p*p];
3F' {JP end
<vx/pH)f figure(1)
L8 K= Q plot(P,P1, P,P2, P,P3);
Z$R6'EUb1 NG-Wn+W@b 转自：
http://blog.163.com/opto_wang/
