计算脉冲在非线性耦合器中演化的Matlab 程序 JYI,N y%cP1y) % This Matlab script file solves the coupled nonlinear Schrodinger equations of
Z"xvh81P % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
I^-Sb=j?Z % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
UcHJR"M~ c % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
rH Lm\3 6P l<'3& %fid=fopen('e21.dat','w');
~Fcm[eo C N = 128; % Number of Fourier modes (Time domain sampling points)
Ty?c C ** M1 =3000; % Total number of space steps
N#_H6 TfMG J =100; % Steps between output of space
z43M] P< T =10; % length of time windows:T*T0
eu-*?]&Di T0=0.1; % input pulse width
k1~&x$G MN1=0; % initial value for the space output location
'rkdZ=x{ dt = T/N; % time step
CY5Z{qiX n = [-N/2:1:N/2-1]'; % Index
IHac:=*Q t = n.*dt;
""G'rN_=Bi u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
-uG +BraI u20=u10.*0.0; % input to waveguide 2
6<QQ@5_ u1=u10; u2=u20;
?);v`] U1 = u1;
FDs>m
#e U2 = u2; % Compute initial condition; save it in U
$Ds2>G4c ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
j</: WRA`] w=2*pi*n./T;
r q].UCj g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
U%QI
a TN* L=4; % length of evoluation to compare with S. Trillo's paper
X&`t{Id?6 dz=L/M1; % space step, make sure nonlinear<0.05
A?P_DA for m1 = 1:1:M1 % Start space evolution
f}P3O3Yv& u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
vp r.Hn u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
+I|vzz`ZVr ca1 = fftshift(fft(u1)); % Take Fourier transform
gR;i(81U ca2 = fftshift(fft(u2));
wlqksG[B c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
tS=(}2Q c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
FT Uv IbT u2 = ifft(fftshift(c2)); % Return to physical space
db7B^|Di
u1 = ifft(fftshift(c1));
}&J q}j if rem(m1,J) == 0 % Save output every J steps.
~B?y{ U1 = [U1 u1]; % put solutions in U array
^hM4j{|&M U2=[U2 u2];
7R\<inCQ MN1=[MN1 m1];
$%#!bV z1=dz*MN1'; % output location
fIU#M]Xx end
aX'*pK/- end
uy$e?{Jf hg=abs(U1').*abs(U1'); % for data write to excel
p_%Rt"! ha=[z1 hg]; % for data write to excel
e* NnVys t1=[0 t'];
?CPahU hh=[t1' ha']; % for data write to excel file
}19\.z&J %dlmwrite('aa',hh,'\t'); % save data in the excel format
iqWQ!r^ figure(1)
]N?kG`[ waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
?Z/V~, figure(2)
hz@bW2S. waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
!Wnb|=j vA8nvoi 非线性超快脉冲耦合的数值方法的Matlab程序 OQJ6e:BGt %IWPM" 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。
2c*GuF9(0 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
|@d\S[~ ^G lt8|9"9< .a Q \jA 8{sGN CvU % This Matlab script file solves the nonlinear Schrodinger equations
t'ql[ % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
EaN6^S= % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
83# mB:^R % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
4H&+dR I" ?6W Y:Zec@ C=1;
[{ ,1=AB M1=120, % integer for amplitude
l]8uk^E M3=5000; % integer for length of coupler
T_4/C2 N = 512; % Number of Fourier modes (Time domain sampling points)
wnC 81$1l~ dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
*$g-:ILRuZ T =40; % length of time:T*T0.
4 ^:=xL dt = T/N; % time step
C~/a- n = [-N/2:1:N/2-1]'; % Index
wFZP,fQ9l t = n.*dt;
< RL] ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Qvhl4-XjZa w=2*pi*n./T;
Ysv"
6b} g1=-i*ww./2;
3[*}4}k9 g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
/j.9$H'y g3=-i*ww./2;
7qS)c}Q\ P1=0;
G4" F +%. P2=0;
|yPu!pf l P3=1;
sfl<qD+? P=0;
N;`n@9BF for m1=1:M1
IH+|}z4N?> p=0.032*m1; %input amplitude
w``U=sfmV s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
] D\D ~!R s1=s10;
A.w.rVDD s20=0.*s10; %input in waveguide 2
SE*g;Cvg1 s30=0.*s10; %input in waveguide 3
u>vL/ nI s2=s20;
o }m3y s3=s30;
l.M0` Cn-% p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
4o5t#qP5$S %energy in waveguide 1
CU!D hm/U p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
El8,,E %energy in waveguide 2
1?l1:}^ L p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
3ckclO\|> %energy in waveguide 3
KM ax$ for m3 = 1:1:M3 % Start space evolution
\s\?l(ooq" s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
;!Fn1|) s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
5|)W. *Q s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
=Dj#gV sca1 = fftshift(fft(s1)); % Take Fourier transform
%8v\FS sca2 = fftshift(fft(s2));
6_B] MN!( sca3 = fftshift(fft(s3));
$%f&a3# sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
2&cT~ZX&' sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
'~ 47)fN sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
j1<Yg,_ .p s3 = ifft(fftshift(sc3));
wC'Szni s2 = ifft(fftshift(sc2)); % Return to physical space
) )Za&S*< s1 = ifft(fftshift(sc1));
#AY&BWS$ end
{ P-): p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
/yZcDK4 p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
~"A0Rs= p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
&H+xz N P1=[P1 p1/p10];
8eRLy/`gd P2=[P2 p2/p10];
|w3M7;~eF P3=[P3 p3/p10];
VIbq:U P=[P p*p];
[V `r^ end
K (|}dl: figure(1)
f6p/5]=J26 plot(P,P1, P,P2, P,P3);
yf,z$CR +ZX{>:vo 转自：
http://blog.163.com/opto_wang/
