计算脉冲在非线性耦合器中演化的Matlab 程序 \v B9f A:* e / ppZ> % This Matlab script file solves the coupled nonlinear Schrodinger equations of
% DHP % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
hwG||;&/H % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
#<^/yoH7C6 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
LK oM\g( Xb8:*Y1' %fid=fopen('e21.dat','w');
C: TuC5Sr N = 128; % Number of Fourier modes (Time domain sampling points)
P<g|y4h M1 =3000; % Total number of space steps
`3H?*\<( J =100; % Steps between output of space
j.e`ip T =10; % length of time windows:T*T0
S<)RVm,!e T0=0.1; % input pulse width
A_8`YN"Xk MN1=0; % initial value for the space output location
bDcWb2 lqs dt = T/N; % time step
INeWi= 1 n = [-N/2:1:N/2-1]'; % Index
@vDgpb@TM t = n.*dt;
4B%5-VQ
u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
'R-JQ E -] u20=u10.*0.0; % input to waveguide 2
ahz@HX u1=u10; u2=u20;
` Mv5!H5l U1 = u1;
+;4AG::GN U2 = u2; % Compute initial condition; save it in U
%K/G+ ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Qg86XU%l w=2*pi*n./T;
lu 9Ir >c g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
)yz9? ]a L=4; % length of evoluation to compare with S. Trillo's paper
Qv T-&| dz=L/M1; % space step, make sure nonlinear<0.05
* U5> j#, for m1 = 1:1:M1 % Start space evolution
M2;(+8 b u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
N:sEC GS, u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
<y b=! ca1 = fftshift(fft(u1)); % Take Fourier transform
EUY a =- ca2 = fftshift(fft(u2));
D[FfJcV'$ c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
cnjj)
c c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
[M zc^I& u2 = ifft(fftshift(c2)); % Return to physical space
b{ubp u1 = ifft(fftshift(c1));
tkUW)ScJ if rem(m1,J) == 0 % Save output every J steps.
n=Z[w5 U1 = [U1 u1]; % put solutions in U array
Cvu8X&y U2=[U2 u2];
`)x U;- MN1=[MN1 m1];
71.:p,Z@z z1=dz*MN1'; % output location
S'H0nJ3 end
ct|'I]nB.h end
PSr t/y! hg=abs(U1').*abs(U1'); % for data write to excel
4< K ,w{I ha=[z1 hg]; % for data write to excel
=G3J.S*Riy t1=[0 t'];
]!S)O|_D[ hh=[t1' ha']; % for data write to excel file
FZ'>LZ %dlmwrite('aa',hh,'\t'); % save data in the excel format
`'tw5} figure(1)
P*qNRP% waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
;V}FbWz^v6 figure(2)
W:N"O\`{m waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
"Jv,QTIcS `peJ s ~V 非线性超快脉冲耦合的数值方法的Matlab程序 =B 4g EWR e7j]BzGvl 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。
v!v0,?b* 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
xuH<=-O>ki ,Elga}7u -QNMB4 5['B-
Iw % This Matlab script file solves the nonlinear Schrodinger equations
) 9sr,3w % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
\gW\Sa ^ % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
S:GUR6g8D % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
&Bdt+ OQ ; '[d dE!ta C=1;
SO jDtZ M1=120, % integer for amplitude
A#07Ly8kXn M3=5000; % integer for length of coupler
(NW N & N = 512; % Number of Fourier modes (Time domain sampling points)
xo"4mbTV dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
z E7ocul T =40; % length of time:T*T0.
XU })3]/ dt = T/N; % time step
NS/L! "g n = [-N/2:1:N/2-1]'; % Index
QvQf@o t = n.*dt;
QbKYB ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
#$z -]i w=2*pi*n./T;
o>,z %+ g1=-i*ww./2;
,/?V+3l g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
KD3To% g3=-i*ww./2;
!Z2n;.w P1=0;
";Xbr;N P2=0;
b2@ x(5# P3=1;
=$z$VbBv P=0;
gB{R6
\<O for m1=1:M1
m_U6"\n 5 p=0.032*m1; %input amplitude
EqDYQ
7 s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
WBIB'2:m s1=s10;
*B~: L "N s20=0.*s10; %input in waveguide 2
Rw ^ YTv s30=0.*s10; %input in waveguide 3
>^ 1S26 s2=s20;
T F3 q?0 s3=s30;
:XY3TI p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
<`p'6n79 %energy in waveguide 1
p$G3r0 @ p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
s 6h Wq&C %energy in waveguide 2
`1v!sSR0R p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
I; }%k;v6 %energy in waveguide 3
d/z X% for m3 = 1:1:M3 % Start space evolution
Fmle| s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
64j 4P 7 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
v})Ti190 s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
+r w3.d sca1 = fftshift(fft(s1)); % Take Fourier transform
PC7 .+;1 sca2 = fftshift(fft(s2));
kb\v}gfiD/ sca3 = fftshift(fft(s3));
( _5+`YsV sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
[hj'Yg 8{ sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
Ln%_8yth sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
#UN{
J6{ s3 = ifft(fftshift(sc3));
~\IDg/9 Cj s2 = ifft(fftshift(sc2)); % Return to physical space
Sqt" G6< s1 = ifft(fftshift(sc1));
q5?mP6 end
[bVP2j p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
&Gwh<%=U p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
Donf9]&U p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
0J-ux"kfI P1=[P1 p1/p10];
9)hC,)5 P2=[P2 p2/p10];
g]Ny?61 P3=[P3 p3/p10];
hQx e0Pdt P=[P p*p];
gUtbCqDS end
rAdcMFW figure(1)
K'/x9.'% plot(P,P1, P,P2, P,P3);
`IQC\DSl/ m D q,, 转自：
http://blog.163.com/opto_wang/
