计算脉冲在非线性耦合器中演化的Matlab 程序 2YaTT& J O~nBz):2 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
Z"4VH rA % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
xu`d`!Tx % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
K90D1sD % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
8xc8L1; an pJAB:1 %fid=fopen('e21.dat','w');
neK*jdaP N = 128; % Number of Fourier modes (Time domain sampling points)
x_]",2 W' M1 =3000; % Total number of space steps
.QNjeMu. J =100; % Steps between output of space
SIj6. RK T =10; % length of time windows:T*T0
{ _": / A T0=0.1; % input pulse width
t*eleNYeS~ MN1=0; % initial value for the space output location
^u= PdBY dt = T/N; % time step
W<Bxm| n = [-N/2:1:N/2-1]'; % Index
: v|r= #OI t = n.*dt;
*;>V2!N=U u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
3we.*\2$ u20=u10.*0.0; % input to waveguide 2
uPM8GIvZX. u1=u10; u2=u20;
Ym3
" U1 = u1;
e? _c[`sg U2 = u2; % Compute initial condition; save it in U
.LWOM8) ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
F+lm [4n w=2*pi*n./T;
V]+o)A$ g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
tU8g(ep,o L=4; % length of evoluation to compare with S. Trillo's paper
Z $ p^v*y dz=L/M1; % space step, make sure nonlinear<0.05
de*,MkZN for m1 = 1:1:M1 % Start space evolution
;a#}fX u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
Xi 1q]ps u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
';i"?D?NAk ca1 = fftshift(fft(u1)); % Take Fourier transform
6RR4L^(m ca2 = fftshift(fft(u2));
rTN"SQt c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
< \qY " .` c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
Y*]l|)a6_] u2 = ifft(fftshift(c2)); % Return to physical space
cq+nWHqF{J u1 = ifft(fftshift(c1));
NN31?wt if rem(m1,J) == 0 % Save output every J steps.
dq IZ#;:g U1 = [U1 u1]; % put solutions in U array
FKDamHL< U2=[U2 u2];
~}hba3&b;# MN1=[MN1 m1];
:V u7,o z1=dz*MN1'; % output location
*[XN.sb8E end
+&&MUT{
3 end
2@"0} po# hg=abs(U1').*abs(U1'); % for data write to excel
@5<]W+jk4 ha=[z1 hg]; % for data write to excel
Ek gZxT_& t1=[0 t'];
l}U~I
3}). hh=[t1' ha']; % for data write to excel file
1]a*Oer} %dlmwrite('aa',hh,'\t'); % save data in the excel format
:)^#
xE( figure(1)
~ v{C 6) waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
S,d ngb{ figure(2)
EF*oPn0| waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
B^Rw?: hN GU;TK'Yy? 非线性超快脉冲耦合的数值方法的Matlab程序 muqfSF Wl9I`Itg 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。
%XDip]+rb 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
mGM inzf b#/V ; ,6cbD F3H:I"4 % This Matlab script file solves the nonlinear Schrodinger equations
rFt ,36 # % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
;T"m [D % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
b 3CspBgC % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
'6d D^0dZ `-9*@_ -=M C=1;
# J <`p M1=120, % integer for amplitude
s)`1Rf M3=5000; % integer for length of coupler
_{F dw N = 512; % Number of Fourier modes (Time domain sampling points)
i uH8g dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
7 ~ % T =40; % length of time:T*T0.
>%jEo'0;_ dt = T/N; % time step
>M8^ Jgh n = [-N/2:1:N/2-1]'; % Index
h[[/p { z t = n.*dt;
`o^;fcnG ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
+r#=n7 t w=2*pi*n./T;
"p6:ekw g1=-i*ww./2;
mPw56> g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
ba:mO$ g3=-i*ww./2;
7 -G'8t P1=0;
|GV Gny< P2=0;
{W:)oh> P3=1;
yv#c =v| P=0;
h q & for m1=1:M1
-G^t-I p=0.032*m1; %input amplitude
;nAg4ll8Q s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
.9[8H:Fe s1=s10;
X T)hPwg. s20=0.*s10; %input in waveguide 2
X{9JSq s30=0.*s10; %input in waveguide 3
'nj&}A' s2=s20;
kVG6\<c] s3=s30;
f@xfb
ie ! p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
^S; RX* %energy in waveguide 1
_sf0{/< ) p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
^%'tD %energy in waveguide 2
!=q:> }g p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
R1b
) %energy in waveguide 3
,N@I cl for m3 = 1:1:M3 % Start space evolution
#G4~]Qml s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
< 4EB|@E s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
Ymk4Cu.s s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
uYFcq sca1 = fftshift(fft(s1)); % Take Fourier transform
CrwcYzrRWl sca2 = fftshift(fft(s2));
J9$]]\52s. sca3 = fftshift(fft(s3));
;o)`9<es!2 sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
@qr3v>3X< sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
[&O:qaD^ sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
%] :vT&M s3 = ifft(fftshift(sc3));
[: hy s2 = ifft(fftshift(sc2)); % Return to physical space
? /|@ #& s1 = ifft(fftshift(sc1));
dnWt\>6&
2 end
lWyP[>* p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
#3:'lGBIK p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
s2' :&5( p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
>-@{ vyoOy P1=[P1 p1/p10];
HV .|Eh_7 P2=[P2 p2/p10];
N mjBJ_ G P3=[P3 p3/p10];
_ry En P=[P p*p];
vdFQf ^l end
B+q+)O+ figure(1)
p ra-8z- plot(P,P1, P,P2, P,P3);
j C1^>D !=Kay^J~. 转自：
http://blog.163.com/opto_wang/
