计算脉冲在非线性耦合器中演化的Matlab 程序 7Hgn/b[?b cg17e % This Matlab script file solves the coupled nonlinear Schrodinger equations of
c ^.^5@ % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
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w6b*O % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
h$6'9 rL&i % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
Haek r*1% dg|x(p# %fid=fopen('e21.dat','w');
J@E]Fl N = 128; % Number of Fourier modes (Time domain sampling points)
:l!sKT?:d! M1 =3000; % Total number of space steps
t!6uz J =100; % Steps between output of space
]BjY UTNm T =10; % length of time windows:T*T0
b$fmU"%&| T0=0.1; % input pulse width
YlGUd~$`"+ MN1=0; % initial value for the space output location
. !Z5 A9^ dt = T/N; % time step
ipp`9 9 n = [-N/2:1:N/2-1]'; % Index
q0Q[]|L t = n.*dt;
R%\3[ u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
3Wbd=^hRvq u20=u10.*0.0; % input to waveguide 2
4dCXBTT u1=u10; u2=u20;
F+Qnf'at1 U1 = u1;
hZL!%sL7 U2 = u2; % Compute initial condition; save it in U
f'(F'TE ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
qK#"uU8B w=2*pi*n./T;
z _\L@ b g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
!-470J L=4; % length of evoluation to compare with S. Trillo's paper
:f 39)g5> dz=L/M1; % space step, make sure nonlinear<0.05
~/-SKGzo- for m1 = 1:1:M1 % Start space evolution
( 'C)S)98C u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
D zE^FY u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
V*Fy@ ca1 = fftshift(fft(u1)); % Take Fourier transform
hLgX0QV ca2 = fftshift(fft(u2));
#-G@ p c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
R=E4Sh c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
iJOG"gI& u2 = ifft(fftshift(c2)); % Return to physical space
uj.$GAtO) u1 = ifft(fftshift(c1));
(_@5V_U if rem(m1,J) == 0 % Save output every J steps.
?&eS }skL U1 = [U1 u1]; % put solutions in U array
{ >[ ]iX U2=[U2 u2];
JWg.0d$hM MN1=[MN1 m1];
#iv4L z1=dz*MN1'; % output location
t`|Rn9- end
,
otXjz end
[qRww]g;P| hg=abs(U1').*abs(U1'); % for data write to excel
@#t<!-8d ha=[z1 hg]; % for data write to excel
nKr'cb t1=[0 t'];
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g?m hh=[t1' ha']; % for data write to excel file
]J!#"m-] %dlmwrite('aa',hh,'\t'); % save data in the excel format
yGt [Qvx# figure(1)
+[uh);vD`G waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
@Q2E1Uu% figure(2)
v@[3R7|4 waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
juWXB+d2Y 9D=X3{be# 非线性超快脉冲耦合的数值方法的Matlab程序 ^ [m-PS( L v/}&'\( 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。
l9eTghLi 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
Nh^I{%.x 8WP"~Js! JJWP te/ 4vG-d)"M2 % This Matlab script file solves the nonlinear Schrodinger equations
kjV>\e % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
">1wPq& % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
"'Fvt-<^S7 % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
dazML|1ow 9ETdO,L)f C=1;
h'h 8Mm M1=120, % integer for amplitude
`V V >AA5 M3=5000; % integer for length of coupler
O^-QqCZE N = 512; % Number of Fourier modes (Time domain sampling points)
?r &~(<^z dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
ll$mRC T =40; % length of time:T*T0.
t/O^7)% dt = T/N; % time step
T|S-?X, n = [-N/2:1:N/2-1]'; % Index
7i xG{yu t = n.*dt;
n5A|Zjk; ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
v}t{* P w=2*pi*n./T;
_/>I-\xWA g1=-i*ww./2;
,WOCG 2h g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
P8dMfD*"E g3=-i*ww./2;
zFO 0l). P1=0;
} #e=*8F7 P2=0;
7lwI]/ZH* P3=1;
I$+=Fb'N0 P=0;
)#\3c,<Y for m1=1:M1
$=E4pb4 Y p=0.032*m1; %input amplitude
x2)WiO/As s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
Gd\ /n*j s1=s10;
8h| } Q _ s20=0.*s10; %input in waveguide 2
^znUf4N1 s30=0.*s10; %input in waveguide 3
$04lL/; s2=s20;
}15&<s s3=s30;
b1IAp >*2l p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
GOA
dhh- %energy in waveguide 1
;7qzQ{Km p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
JP\jhkn %energy in waveguide 2
3
I%N4K4 p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
g]z k` R5 %energy in waveguide 3
8 NNh8k#6 for m3 = 1:1:M3 % Start space evolution
cOpe6H6,bz s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
1:T"jsWw s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
!f Av xR s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
HX| p4-L sca1 = fftshift(fft(s1)); % Take Fourier transform
I(BJ1 8F$ sca2 = fftshift(fft(s2));
0#Ug3_dfr sca3 = fftshift(fft(s3));
-WyB2$!( sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
r>bgCQ#-n sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
_,K[kVn sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
3A"TpR4f` s3 = ifft(fftshift(sc3));
o l_\ " s2 = ifft(fftshift(sc2)); % Return to physical space
/ O.q 4p s1 = ifft(fftshift(sc1));
[vb#W!M&| end
Q wFA0 p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
=eW4?9Uq p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
Y}.f&rLe p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
1nvT={'R P1=[P1 p1/p10];
Er@xrhH P2=[P2 p2/p10];
{ GCp5 P3=[P3 p3/p10];
I' {Ctc P=[P p*p];
O z(=%oS end
A~>B?Wijqg figure(1)
hUvA;E(qD plot(P,P1, P,P2, P,P3);
&DYC3*)Jih ='kCY}dkO 转自：
http://blog.163.com/opto_wang/
