计算脉冲在非线性耦合器中演化的Matlab 程序 S mjg [ \UR/tlw+/ % This Matlab script file solves the coupled nonlinear Schrodinger equations of
_6/q. % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
j+-+<h/( % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
H6! <y- % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
C?h`i ^ >2 "JBTsQDj! %fid=fopen('e21.dat','w');
P3u,)P& N = 128; % Number of Fourier modes (Time domain sampling points)
1}>u Y M1 =3000; % Total number of space steps
I6B4S"Q5< J =100; % Steps between output of space
" +n\0j ; T =10; % length of time windows:T*T0
!5escR!\D T0=0.1; % input pulse width
*]]C.t-cd MN1=0; % initial value for the space output location
/N?vVp dt = T/N; % time step
q(YFt* (;w n = [-N/2:1:N/2-1]'; % Index
I,0Z* rw t = n.*dt;
yD n 8{uI u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
I nCo[ 8SI u20=u10.*0.0; % input to waveguide 2
QZ:xG:qyk; u1=u10; u2=u20;
m=.}}DcSs U1 = u1;
n>-"\cjV U2 = u2; % Compute initial condition; save it in U
!v`C-1}70 ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Wgr`)D w=2*pi*n./T;
Mq [|w2. g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
2B<0|EGtzw L=4; % length of evoluation to compare with S. Trillo's paper
3Hg}G#]WS dz=L/M1; % space step, make sure nonlinear<0.05
Bx&F* a;5 for m1 = 1:1:M1 % Start space evolution
``j8T[ g u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
7\e96+j|f u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
g\O&gNq<)- ca1 = fftshift(fft(u1)); % Take Fourier transform
^>H+#@R ca2 = fftshift(fft(u2));
LG6 k
KG c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
e_{!8u.+ c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
28rC>*+z u2 = ifft(fftshift(c2)); % Return to physical space
H*&ZX AKv u1 = ifft(fftshift(c1));
?5yj</W if rem(m1,J) == 0 % Save output every J steps.
! !9l@ U1 = [U1 u1]; % put solutions in U array
SSh=r U2=[U2 u2];
W<"{d MN1=[MN1 m1];
rt5eN:'qY z1=dz*MN1'; % output location
i9FtS7 end
b }OOG end
C1 YG=! hg=abs(U1').*abs(U1'); % for data write to excel
_s> ZY0 ha=[z1 hg]; % for data write to excel
[q5N 4&q\ t1=[0 t'];
:a#p zEK hh=[t1' ha']; % for data write to excel file
1G6 MO %dlmwrite('aa',hh,'\t'); % save data in the excel format
>tFv&1iR figure(1)
^& R
H]q waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
^t wJNm{99 figure(2)
z%pD3J ?> waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
nR()ei^X D#?jd dr- 非线性超快脉冲耦合的数值方法的Matlab程序 /j0zb& /V% ]lmxQ 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。
djxM/"xo 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
J/o$\8tiMw D " 4*& (3;dtp>Xx ^ew<|J2,B % This Matlab script file solves the nonlinear Schrodinger equations
S
;; Z % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
'\iW p?`$ % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
$)fybn Y % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
U.[?1: v \f AL:mJ C=1;
1>!wm 0;x M1=120, % integer for amplitude
s, 8a1o M3=5000; % integer for length of coupler
jD
eNCJ N = 512; % Number of Fourier modes (Time domain sampling points)
RXj6L~vs5_ dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
3hr ODts T =40; % length of time:T*T0.
`S{Blv dt = T/N; % time step
=CE(M},d n = [-N/2:1:N/2-1]'; % Index
E9yBa=#*c t = n.*dt;
v FL\O ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
i{$h]D_fD w=2*pi*n./T;
Po: )b g1=-i*ww./2;
# XD-a g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
bxS+ R\ g3=-i*ww./2;
3N ] P1=0;
/W6 r{Et P2=0;
71h?t `N P3=1;
u* <G20~A P=0;
0H6^2T< for m1=1:M1
~
}<!ON; p=0.032*m1; %input amplitude
h] #wwJF s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
+foyPj!% s1=s10;
r. V< 5xV s20=0.*s10; %input in waveguide 2
= 7Wr s30=0.*s10; %input in waveguide 3
C98 Ks s2=s20;
7D;g\{>M s3=s30;
+6xEz67A< p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
Pkm3&sW
%energy in waveguide 1
~x>?1 K p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
# h 4`f %energy in waveguide 2
]/p)XHKo p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
'e3 [m %energy in waveguide 3
|^ao,3h# for m3 = 1:1:M3 % Start space evolution
oM@X)6P_ s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
|Q'l&Gt6 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
zLs[vg.( s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
H@u C bT sca1 = fftshift(fft(s1)); % Take Fourier transform
{ER%r'(4Z sca2 = fftshift(fft(s2));
8qEK6- sca3 = fftshift(fft(s3));
@CSTp6{y sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
COx<X\ sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
kW#{[,7r sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
#l(cBM9sz s3 = ifft(fftshift(sc3));
(L)tC*Qjc
s2 = ifft(fftshift(sc2)); % Return to physical space
@+v;B: s1 = ifft(fftshift(sc1));
P | [i{h end
2[\I{<2/9 p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
EcA @bZ0 p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
9M)N2+hkZ p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
,Z7tpFC P1=[P1 p1/p10];
i6^COr P2=[P2 p2/p10];
dz', !|> P3=[P3 p3/p10];
%C]K`=vI- P=[P p*p];
2/9P&c-r p end
}Om+,!_d figure(1)
Z7eD+4gD plot(P,P1, P,P2, P,P3);
!cs +tm3 s^nwF> 转自：
http://blog.163.com/opto_wang/
