计算脉冲在非线性耦合器中演化的Matlab 程序 &*>.u8:r T+nID@"36 % This Matlab script file solves the coupled nonlinear Schrodinger equations of
iH4LZ % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
Lq5 xp< % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
(a#gCG\ % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
j yD3Sa3 U.,S.WP+d %fid=fopen('e21.dat','w');
%4m Nk}tyH N = 128; % Number of Fourier modes (Time domain sampling points)
g_cED15 M1 =3000; % Total number of space steps
vcdVck@ J =100; % Steps between output of space
0]bt}rh T =10; % length of time windows:T*T0
e:Y+ -C5 T0=0.1; % input pulse width
(*$ F7oO< MN1=0; % initial value for the space output location
YA$YT8iMe dt = T/N; % time step
w"?Q0bhV9y n = [-N/2:1:N/2-1]'; % Index
Qz(2Iu{E] t = n.*dt;
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& N u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
#epbc K u20=u10.*0.0; % input to waveguide 2
':pDlUA u1=u10; u2=u20;
,Tr&`2w U1 = u1;
#4mRMsW5" U2 = u2; % Compute initial condition; save it in U
?)-6~p 4N ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
L0 "|4= w=2*pi*n./T;
r{v3 XD/ g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
Uo >aQk L=4; % length of evoluation to compare with S. Trillo's paper
%urvX$r4K dz=L/M1; % space step, make sure nonlinear<0.05
3S3( G l for m1 = 1:1:M1 % Start space evolution
x3cjyu<K u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
~'lT8 n_ u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
syB pF:`-W ca1 = fftshift(fft(u1)); % Take Fourier transform
5zBA ]1PY ca2 = fftshift(fft(u2));
F2}F uupb. c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
]]K?Q
)9x c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
Kj 4 BVs u2 = ifft(fftshift(c2)); % Return to physical space
t$n Jmfzm u1 = ifft(fftshift(c1));
>
pb}@\;: if rem(m1,J) == 0 % Save output every J steps.
)). =MTk U1 = [U1 u1]; % put solutions in U array
`[5xncZ- U2=[U2 u2];
&zF>5@ fM MN1=[MN1 m1];
B-N//ef} z1=dz*MN1'; % output location
C/Q 20 end
"O>~osj end
z )hK 2JD hg=abs(U1').*abs(U1'); % for data write to excel
[ <f2h-V$ ha=[z1 hg]; % for data write to excel
Ag9GYm t1=[0 t'];
d]e36Dwk hh=[t1' ha']; % for data write to excel file
UCcr > %dlmwrite('aa',hh,'\t'); % save data in the excel format
c
qCNk figure(1)
2*V%S/cck waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
s`=| D'G(= figure(2)
f4 S:L& waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
K>+ v" x 0]7jb_n1 非线性超快脉冲耦合的数值方法的Matlab程序 g/. FJ-I* =F_ uK7W 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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Or Qf` 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
Db Qp (W0 ,JdB Vt s U`#hL6; R L4|!HzR % This Matlab script file solves the nonlinear Schrodinger equations
Z0Sqw % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
(E0WZ $f} % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
dY}5Kmt % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
<~uzHg%Y ?MFC(Wsh
C=1;
\m|5Aqs M1=120, % integer for amplitude
pP.`+vPi M3=5000; % integer for length of coupler
&'12,'8 N = 512; % Number of Fourier modes (Time domain sampling points)
F'[Y.tA ,# dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
#9TL5-1y T =40; % length of time:T*T0.
L;:PeYPL dt = T/N; % time step
S*G^U1Sc+ n = [-N/2:1:N/2-1]'; % Index
x~}&t+FK t = n.*dt;
^Ak?2,xB#+ ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
uq]=L w=2*pi*n./T;
k:?)0Uh%^ g1=-i*ww./2;
IrYj#,xJ g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
{H,O@ g3=-i*ww./2;
$Mg O)bH P1=0;
=M?+KbTJ3 P2=0;
b)IQa,enH P3=1;
c=t bl|Cq P=0;
+I uu8t for m1=1:M1
r8 YM#d F p=0.032*m1; %input amplitude
t" Du s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
;L fn&2G s1=s10;
tLKf]5}f s20=0.*s10; %input in waveguide 2
& <*M{GW'& s30=0.*s10; %input in waveguide 3
G!VEV3zT s2=s20;
D 6lzc f s3=s30;
8zMGpY# p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
uzQ j+Po %energy in waveguide 1
02EX_tt), p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
Zq33R` %energy in waveguide 2
U~BR8]=G p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
tOVTHx3E] %energy in waveguide 3
{=?[:5 for m3 = 1:1:M3 % Start space evolution
92Gfxld\ s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
<=|^\r
!}& s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
pWE(?d_M{G s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
{w3 <df J sca1 = fftshift(fft(s1)); % Take Fourier transform
O6$,J1 2l sca2 = fftshift(fft(s2));
y`m0/SOT sca3 = fftshift(fft(s3));
el$@^Wy&$ sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
b' ^<0c sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
=g6~2p=H sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
5I[:.o0 s3 = ifft(fftshift(sc3));
b&E"r*i| s2 = ifft(fftshift(sc2)); % Return to physical space
eptw)S-j s1 = ifft(fftshift(sc1));
D@X"1X!F`G end
Rm n|!C%%K p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
h y#nK: B p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
]Z UE ! p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
u)EtEl7Wq P1=[P1 p1/p10];
1Bs t| P2=[P2 p2/p10];
ghW`xm87 P3=[P3 p3/p10];
r-S%gG}~E P=[P p*p];
~a
V5 end
!c k luj figure(1)
F&p42!" plot(P,P1, P,P2, P,P3);
q@S \R
7R _~1O #*|4 转自：
http://blog.163.com/opto_wang/
