计算脉冲在非线性耦合器中演化的Matlab 程序 8 OY 3A de.&`lPRf % This Matlab script file solves the coupled nonlinear Schrodinger equations of
52:HNA\E/ % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
uwzvb gup? % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
,J,/."Y % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
iU$] {c2;A r e/@D@% %fid=fopen('e21.dat','w');
} ()5"QB N = 128; % Number of Fourier modes (Time domain sampling points)
#lmB
AL~3 M1 =3000; % Total number of space steps
*scVJ J =100; % Steps between output of space
KHe=O1 %QO T =10; % length of time windows:T*T0
>7lx=T
x T0=0.1; % input pulse width
[I '0,y MN1=0; % initial value for the space output location
*6sl dt = T/N; % time step
i
UCXAWP n = [-N/2:1:N/2-1]'; % Index
g7}Gip}.> t = n.*dt;
U `R5 'Tf; u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
1"zDin!A u20=u10.*0.0; % input to waveguide 2
)97SnCkal u1=u10; u2=u20;
8ja$g, U1 = u1;
sF!($k;! U2 = u2; % Compute initial condition; save it in U
|n+qMql' ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
(D#B_`;- w=2*pi*n./T;
%<k2#6K g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
c`J.Tm[_u L=4; % length of evoluation to compare with S. Trillo's paper
QLXN*c dz=L/M1; % space step, make sure nonlinear<0.05
7C,&*Ax,9 for m1 = 1:1:M1 % Start space evolution
E27vR 7 u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
6h|q'.Y u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
t[ubn+ ca1 = fftshift(fft(u1)); % Take Fourier transform
V=R 3)GC ca2 = fftshift(fft(u2));
K-bD<X c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
R<\F:9 c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
%eX{WgH u2 = ifft(fftshift(c2)); % Return to physical space
QQ%D8$k" u1 = ifft(fftshift(c1));
.>= (' - if rem(m1,J) == 0 % Save output every J steps.
f!\l g U1 = [U1 u1]; % put solutions in U array
tj Il -IQ U2=[U2 u2];
!nqUB a MN1=[MN1 m1];
/qMG=Z z1=dz*MN1'; % output location
+ln9c end
3.|S end
S=5<^o^h3 hg=abs(U1').*abs(U1'); % for data write to excel
(U&tt]| ha=[z1 hg]; % for data write to excel
QKyo`g7 t1=[0 t'];
}+)fMZz hh=[t1' ha']; % for data write to excel file
gp5_Z-me %dlmwrite('aa',hh,'\t'); % save data in the excel format
C"6?bg5N figure(1)
<v)1<*I waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
KC/=TSSXd. figure(2)
pOGeru u? waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
gRCdY8GH 't1 ax^-g 非线性超快脉冲耦合的数值方法的Matlab程序 'C`U"I !k 6K?xt 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。
?{/4b:ua 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
>pU$wq|i Lx\ 8Z= p2ogn}` T ? $:'XJ % This Matlab script file solves the nonlinear Schrodinger equations
s %qF/70' % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
!Y$h"<M % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
fmQ_P.c % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
q1z"-~i )E ZI f C=1;
D ~stM M1=120, % integer for amplitude
;|p BFKx M3=5000; % integer for length of coupler
Y'1S`. N = 512; % Number of Fourier modes (Time domain sampling points)
kw#;w=\>R{ dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
zDw5]*R T =40; % length of time:T*T0.
mtJ9nC dt = T/N; % time step
N/Z2hn/m n = [-N/2:1:N/2-1]'; % Index
:Pvzl1 t = n.*dt;
\DYWy*pe ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
!F1M(zFD w=2*pi*n./T;
T^Y([23 g1=-i*ww./2;
a2dnbfSWa[ g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
I/a/ )No g3=-i*ww./2;
;1:Js0=;H P1=0;
x.f]1S7h[ P2=0;
ZG>PQA P3=1;
{1 IfU P=0;
IEXt: for m1=1:M1
kddZZA3` p=0.032*m1; %input amplitude
(MR_^t s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
>64P6P;S s1=s10;
uehDIl0\[b s20=0.*s10; %input in waveguide 2
$K]m{ s30=0.*s10; %input in waveguide 3
Fgp]l2* s2=s20;
v:!Z=I}> s3=s30;
byLft 1 p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
H=g`hF]` %energy in waveguide 1
M!/Cknm p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
jE}33" %energy in waveguide 2
;g @4|Ro p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
-&3hEv5 %energy in waveguide 3
mzeY%A <0^ for m3 = 1:1:M3 % Start space evolution
;LG#.~f s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
JBi*P.79^ s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
}\%Fi/6Z { s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
<R''oEf9 sca1 = fftshift(fft(s1)); % Take Fourier transform
?98("T|y; sca2 = fftshift(fft(s2));
;%<,IdhN sca3 = fftshift(fft(s3));
jFA SX2.p sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
L;*ljZ^c sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
P0W*C6&71| sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
G_0(
|% s3 = ifft(fftshift(sc3));
> +JqA7K s2 = ifft(fftshift(sc2)); % Return to physical space
[U5\bX@$ s1 = ifft(fftshift(sc1));
VKq=7^W end
HkO7 R
` p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
" t (p&;d p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
P!H_1RwXKC p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
vbb 5f #WZ P1=[P1 p1/p10];
bmf I ~8 P2=[P2 p2/p10];
[P&7i57 P3=[P3 p3/p10];
J T-J#Ag P=[P p*p];
Kla'lCZ end
f4Xk,1Is figure(1)
0\[Chja plot(P,P1, P,P2, P,P3);
te3}d'9&| v.pBX< 转自：
http://blog.163.com/opto_wang/
