计算脉冲在非线性耦合器中演化的Matlab 程序 0g=`DSC<( iL]'y\?lv % This Matlab script file solves the coupled nonlinear Schrodinger equations of
l7}g^\I % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
cYNV\b4- % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
+wO#'D % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
Q2|p \rO T:iP="?{ %fid=fopen('e21.dat','w');
p(JlvJjo N = 128; % Number of Fourier modes (Time domain sampling points)
oPQtGl p M1 =3000; % Total number of space steps
b-^p1{A0zW J =100; % Steps between output of space
LT@O WH T =10; % length of time windows:T*T0
r[t xlQI9 T0=0.1; % input pulse width
!mJo'K MN1=0; % initial value for the space output location
uJU*")\V dt = T/N; % time step
sLL7]m} n = [-N/2:1:N/2-1]'; % Index
'UU\4M t = n.*dt;
:t("L-GPW u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
~I=Y{iM u20=u10.*0.0; % input to waveguide 2
0?DC00O u1=u10; u2=u20;
K^l:MxO-X U1 = u1;
/t%u"dP"T~ U2 = u2; % Compute initial condition; save it in U
iw9Q18:I} ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
b=;nm#cAI w=2*pi*n./T;
;#/@+4@a& g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
vH[47Cv G5 L=4; % length of evoluation to compare with S. Trillo's paper
pB:$lS dz=L/M1; % space step, make sure nonlinear<0.05
RFaSw f,5n for m1 = 1:1:M1 % Start space evolution
p#P~Q/; u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
eU@Cr7@,| u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
23\RJpKb ca1 = fftshift(fft(u1)); % Take Fourier transform
Z.PBu| Kx ca2 = fftshift(fft(u2));
K2)!h.W c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
hqvE!Of c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
c re;P5^E u2 = ifft(fftshift(c2)); % Return to physical space
d3Mva,bw< u1 = ifft(fftshift(c1));
W_|0y4QOo if rem(m1,J) == 0 % Save output every J steps.
4u;9J*r4 U1 = [U1 u1]; % put solutions in U array
J:*-gwv9*m U2=[U2 u2];
r=uN9ro MN1=[MN1 m1];
=uHnRY z1=dz*MN1'; % output location
K5>p89mZ end
"/Pjjb:2 end
56lCwXCgA hg=abs(U1').*abs(U1'); % for data write to excel
/1UOT\8U ha=[z1 hg]; % for data write to excel
7cDU2l t1=[0 t'];
LW6ZAETyL hh=[t1' ha']; % for data write to excel file
`r"+644 %dlmwrite('aa',hh,'\t'); % save data in the excel format
Ws U)Y& figure(1)
9m2, qr| waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
!|hoYU>@2L figure(2)
)- 15 N waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
1$/MrPT(b 3g'S\ G@ 非线性超快脉冲耦合的数值方法的Matlab程序 (& "su3z t_z >Cl^u 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。
))kF<A_MK 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
3rW|kkn S^@S%Eg }_/ Hd mmx .~A*= % This Matlab script file solves the nonlinear Schrodinger equations
AN:sQX` % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
z}QwP~Z % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
lf{e[!ML' % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
<P[T!gST 9_ s6l C=1;
z<sg0K8z63 M1=120, % integer for amplitude
G'2#9<c* M3=5000; % integer for length of coupler
:NHH
Dl N = 512; % Number of Fourier modes (Time domain sampling points)
9O`
m,t dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
{^ mNJ T =40; % length of time:T*T0.
5,qj7HZF dt = T/N; % time step
d<!3`qe n = [-N/2:1:N/2-1]'; % Index
/tV/85r t = n.*dt;
? &G`{Ey ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
6vuq1 w=2*pi*n./T;
S:4cr I g1=-i*ww./2;
q5h*` 7f g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
Ds #/ g3=-i*ww./2;
4a0:2 kIKa P1=0;
fx=Awba P2=0;
'w>_+jLT P3=1;
d2oh/j6`TA P=0;
O ,rwP for m1=1:M1
>EL)X
#e p=0.032*m1; %input amplitude
8`4<R6]LKB s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
9CA^B2 u s1=s10;
IEKU-k7}Z s20=0.*s10; %input in waveguide 2
>_rha~ s30=0.*s10; %input in waveguide 3
i|w8.}0 s2=s20;
xq-17HKs s3=s30;
[Vd[- p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
NaVQ9ku7VW %energy in waveguide 1
/27JevE p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
Vd".u'r %energy in waveguide 2
l zw3= H p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
ul%h@=n %energy in waveguide 3
w%WF-:u7| for m3 = 1:1:M3 % Start space evolution
V fv@7@q s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
<VD8bTk s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
7g
R@$(1Z s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
h\ plQ[T sca1 = fftshift(fft(s1)); % Take Fourier transform
JnHo 9K2. sca2 = fftshift(fft(s2));
>fH=DOz$& sca3 = fftshift(fft(s3));
a+hd(JX0~ sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
-.g|l\ sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
|mdi]TL sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
g{W;I_P^9 s3 = ifft(fftshift(sc3));
d(g^M1 m s2 = ifft(fftshift(sc2)); % Return to physical space
~m|Mg9- s1 = ifft(fftshift(sc1));
u0P)7~% end
u6`=x$& p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
* ),8PoT p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
(`SRJ$~f p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
*~m+Nc`D,N P1=[P1 p1/p10];
&1+X\c+t b P2=[P2 p2/p10];
&/Ro lIHF P3=[P3 p3/p10];
Bo<>e~6P P=[P p*p];
8$(Dz]v|[& end
!LkW zn3 figure(1)
YF+n
b.0. plot(P,P1, P,P2, P,P3);
aM7uBx\8 5 S1D@vnZ3O\ 转自：
http://blog.163.com/opto_wang/
