计算脉冲在非线性耦合器中演化的Matlab 程序 (zBQ^97] eW0=m:6 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
R5"p 7> % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
+b+sQ<w?. % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
Qx;A; n!lw % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
jvQ"cs$. :!$z1u8R %fid=fopen('e21.dat','w');
PS6`o N = 128; % Number of Fourier modes (Time domain sampling points)
J~q+ G M1 =3000; % Total number of space steps
919g5f` J =100; % Steps between output of space
l'QR2r7&. T =10; % length of time windows:T*T0
F6p1 VFs T0=0.1; % input pulse width
<Z' hZ MN1=0; % initial value for the space output location
p( *3U[1 dt = T/N; % time step
t5h_Q92N n = [-N/2:1:N/2-1]'; % Index
1!3kAcBP t = n.*dt;
W1 Qc1T8 u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
F/sBr7I u20=u10.*0.0; % input to waveguide 2
Gq/6{eRo\ u1=u10; u2=u20;
T;@> O^ U1 = u1;
Wi^rnr'S s U2 = u2; % Compute initial condition; save it in U
s~
A8/YoU} ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
|@.<} / w=2*pi*n./T;
s.' \&B[ g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
aUK4{F ; L=4; % length of evoluation to compare with S. Trillo's paper
e6lOmgHn5 dz=L/M1; % space step, make sure nonlinear<0.05
zF&UdS3 for m1 = 1:1:M1 % Start space evolution
*GP_ut% u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
RFY!o<
u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
YS~t d+* ca1 = fftshift(fft(u1)); % Take Fourier transform
)H)Udhz ca2 = fftshift(fft(u2));
'V #ew\ c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
]0 RX o3 c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
RWCS
u$ u2 = ifft(fftshift(c2)); % Return to physical space
RH]>>tJ^e u1 = ifft(fftshift(c1));
~qxXou,J if rem(m1,J) == 0 % Save output every J steps.
?4e6w U1 = [U1 u1]; % put solutions in U array
l- }5@D[ U2=[U2 u2];
z \>X[yNpA MN1=[MN1 m1];
$?A A" Nz z1=dz*MN1'; % output location
@T1+b"TC end
]31 XX= end
9ox|. 68q hg=abs(U1').*abs(U1'); % for data write to excel
0WE1}.J< ha=[z1 hg]; % for data write to excel
e8mbEC(AK t1=[0 t'];
uhB!k-ir hh=[t1' ha']; % for data write to excel file
F J8@b %dlmwrite('aa',hh,'\t'); % save data in the excel format
@jSbMI figure(1)
d`uO7jlm waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
PMhhPw] figure(2)
++DQS9b{ waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
yr2L puN=OX}C 非线性超快脉冲耦合的数值方法的Matlab程序 u# WTh%/ T% 13 ' 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。
,G|aLBn 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
k_>Fw>Y 6\fMzm
kN |5
J ,GkW. vEU % This Matlab script file solves the nonlinear Schrodinger equations
ikN!ut % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
6 8<Z\WP % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
rn:zKTyhw % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
\UqS -j| 4:&qT Y)H C=1;
HJaw\zbL M1=120, % integer for amplitude
a`b zFu{ M3=5000; % integer for length of coupler
aT:AxYn8 N = 512; % Number of Fourier modes (Time domain sampling points)
}?]yxa ~ dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
uO@3vY',n T =40; % length of time:T*T0.
hr4ye`c j dt = T/N; % time step
x2;i<
| n = [-N/2:1:N/2-1]'; % Index
>q@ Sd t = n.*dt;
?koxt4 4 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
{&=qM!2e w=2*pi*n./T;
bLEATT[ g1=-i*ww./2;
2k}-25xxL g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
51G=RYay9 g3=-i*ww./2;
fA_%8CjI P1=0;
KBw9( P2=0;
R G0S P3=1;
}PQSCl^I P=0;
yvd
`nV for m1=1:M1
QhX C>)PW p=0.032*m1; %input amplitude
daB l%a= s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
% 7 v@n+Q s1=s10;
6L,lq; s20=0.*s10; %input in waveguide 2
9Ue7
~"= s30=0.*s10; %input in waveguide 3
l^ 0_> R s2=s20;
yw.~trF&% s3=s30;
3p3WDL7 p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
O5 qW*r' %energy in waveguide 1
2 zKo p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
TD{=L*{+ %energy in waveguide 2
r%F(?gKXkd p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
n{^<&GWox %energy in waveguide 3
f(6UL31 for m3 = 1:1:M3 % Start space evolution
O}MZ-/z=o~ s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
@q+cm JKv s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
kOAY@a s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
d]CviQUq sca1 = fftshift(fft(s1)); % Take Fourier transform
z$ c&=Q sca2 = fftshift(fft(s2));
,rZ n`9 sca3 = fftshift(fft(s3));
L$lo~7<] sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
ZD)0P=% sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
}KA-t}8 sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
W(2+z5 z s3 = ifft(fftshift(sc3));
lmhbF s2 = ifft(fftshift(sc2)); % Return to physical space
#d Z/UM(u s1 = ifft(fftshift(sc1));
VFl 1 f end
%6A-OF p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
Y9i9Uc.] p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
,@Fgr(?'`> p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
E kBae= P1=[P1 p1/p10];
`RL,ZoYuu P2=[P2 p2/p10];
~v2V`lxh P3=[P3 p3/p10];
?ds f@\ P=[P p*p];
=[P%_v`` end
Kc%n(,+%" figure(1)
=w ^TcV plot(P,P1, P,P2, P,P3);
D3S+ LV z;dcAdz9 转自：
http://blog.163.com/opto_wang/
