计算脉冲在非线性耦合器中演化的Matlab 程序 6w(6}m.L^ <- D0 u?8 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
IuRmEL_Q_ % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
$+ 3}po\ % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
dRaNzK)M % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
FcYFovS 7 El[ > %fid=fopen('e21.dat','w');
/(BMG/Tb N = 128; % Number of Fourier modes (Time domain sampling points)
Hqn#yInA7~ M1 =3000; % Total number of space steps
/gu%:vq J =100; % Steps between output of space
vc+A RgvH+ T =10; % length of time windows:T*T0
[.S#rGYk T0=0.1; % input pulse width
qh2ON>e; MN1=0; % initial value for the space output location
,J{ei7TN dt = T/N; % time step
2m35R& n = [-N/2:1:N/2-1]'; % Index
% ve:hym* t = n.*dt;
JMz;BAHT u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
N 0= ac5 u20=u10.*0.0; % input to waveguide 2
!cA yTl(_ u1=u10; u2=u20;
%d(^d U1 = u1;
c(n&A~*AJ% U2 = u2; % Compute initial condition; save it in U
u( wGl_ ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
e*;c(3>( w=2*pi*n./T;
B {C??g8/ g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
Q Z:8+[oy L=4; % length of evoluation to compare with S. Trillo's paper
*i- _6s dz=L/M1; % space step, make sure nonlinear<0.05
$} =krz:r for m1 = 1:1:M1 % Start space evolution
%JHGiCv| u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
?$6Y2 u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
B,@ c; K ca1 = fftshift(fft(u1)); % Take Fourier transform
N%"Y ca2 = fftshift(fft(u2));
YJ;j x0 c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
L_+k12lm c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
(jFGa2{ u2 = ifft(fftshift(c2)); % Return to physical space
v%s`~~u%^ u1 = ifft(fftshift(c1));
I]&#Dl / if rem(m1,J) == 0 % Save output every J steps.
LjUy*mxw U1 = [U1 u1]; % put solutions in U array
W81E!RyP` U2=[U2 u2];
R&Jm
+3N MN1=[MN1 m1];
r!HwXeEn/ z1=dz*MN1'; % output location
'iGzkf}j end
+tk{"s^r* end
""1^k2fj hg=abs(U1').*abs(U1'); % for data write to excel
2#<xAR ha=[z1 hg]; % for data write to excel
L}}y'^( t1=[0 t'];
1!1 beR] hh=[t1' ha']; % for data write to excel file
l*k POyB %dlmwrite('aa',hh,'\t'); % save data in the excel format
3&[>u;Bp figure(1)
j|/]#@Yr waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
9v }G{mQ# figure(2)
7A\~)U @ waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
MwR 0@S}* 0LfU=X0#7 非线性超快脉冲耦合的数值方法的Matlab程序 jGEt+\"/QJ a e*M f7 在研究脉冲在非线性耦合器中的演变时，我们需要求解非线性偏微分方程组。在如下的
论文中，我们提出了一种简洁的数值方法。 这里我们提供给大家用Matlab编写的计算程序。
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s5g!: Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
o A =4=` |iR T!
] mN>h5G>a =ZDAeVz3w % This Matlab script file solves the nonlinear Schrodinger equations
=7 C%P%yt % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
mXUGe:e8 % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
NLr PSqz % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
VGceD$< '{J&M|<A C=1;
B:e
@0049 M1=120, % integer for amplitude
\L(*]:EP M3=5000; % integer for length of coupler
Pj4/ xX N = 512; % Number of Fourier modes (Time domain sampling points)
e#Z$o($t dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
L dm?JrU T =40; % length of time:T*T0.
+> WM[o^I dt = T/N; % time step
(d< 4"! n = [-N/2:1:N/2-1]'; % Index
;[W"m lM t = n.*dt;
)E,\H@A ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Rhe R e w=2*pi*n./T;
-Y
H< g1=-i*ww./2;
Ci<ATho g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
*3& f qBg g3=-i*ww./2;
]6{*^4 kX P1=0;
,daKC P2=0;
|{@8 m9JR P3=1;
uFLx P=0;
66'?&Xx' for m1=1:M1
wAz &"rS p=0.032*m1; %input amplitude
Oer^ Rk s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
RtCkV xaEx s1=s10;
>TP7 }u| s20=0.*s10; %input in waveguide 2
Ma\ Gb+> s30=0.*s10; %input in waveguide 3
dpFVN[\oK s2=s20;
lr{?"tl_ s3=s30;
Z-U- N p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
]_8qn '7 %energy in waveguide 1
L9@ &2 ?k p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
EM/@T} %energy in waveguide 2
Ai/b\:V9S p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
w 1Ec_y { %energy in waveguide 3
*JaqTI,e for m3 = 1:1:M3 % Start space evolution
;?6No(/ s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
/MF! GM s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
(&P9+Tl s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
8-lOB sca1 = fftshift(fft(s1)); % Take Fourier transform
4<?8M vF sca2 = fftshift(fft(s2));
`KCh*i sca3 = fftshift(fft(s3));
~j#]tEl b sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
V %_4% sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
z)xSN;x sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
? B E6 s3 = ifft(fftshift(sc3));
"F}'~HWZp s2 = ifft(fftshift(sc2)); % Return to physical space
:gB[O>'<m s1 = ifft(fftshift(sc1));
<N`J`J-[ end
PI~1GyJr@; p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
0V{(Ru.O p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
2<][%> ' p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
x+h~gckLb P1=[P1 p1/p10];
e+]6O V&+ P2=[P2 p2/p10];
=;3fq- P3=[P3 p3/p10];
A 5+rd{k / P=[P p*p];
cPl`2&p end
|hO~X~P figure(1)
p[@5&_u(z plot(P,P1, P,P2, P,P3);
b-Z4
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G q\q=PB6r 转自：
http://blog.163.com/opto_wang/
