计算脉冲在非线性耦合器中演化的Matlab 程序 tv5G']vO\ ml\A)8O]j/ % This Matlab script file solves the coupled nonlinear Schrodinger equations of
K%O%#Kk % soliton in 2 cores coupler. The output pulse evolution plot is shown in Fig.1 of
z.--"c F % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
4Z,MqG> % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
.hXxh)F ,..&j+m %fid=fopen('e21.dat','w');
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X N = 128; % Number of Fourier modes (Time domain sampling points)
}[k~JXt M1 =3000; % Total number of space steps
rUR{MF &]D J =100; % Steps between output of space
9ELLJ@oNC T =10; % length of time windows:T*T0
;kDz9Va T0=0.1; % input pulse width
gh#9< MN1=0; % initial value for the space output location
Z+x,Aw q dt = T/N; % time step
h@&& .S`B n = [-N/2:1:N/2-1]'; % Index
x[zt(kC0+ t = n.*dt;
,E<(K8 u10=1.*sech(1*t); % input to waveguide1 amplitude: power=u10*u10
/^SIJS@^`> u20=u10.*0.0; % input to waveguide 2
[2:Q.Zj u1=u10; u2=u20;
vvwNJyU- U1 = u1;
qS:h v&~ U2 = u2; % Compute initial condition; save it in U
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ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
Z_Qs^e$ w=2*pi*n./T;
x 4Q*~,n g=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./T
u1R_u9 L=4; % length of evoluation to compare with S. Trillo's paper
$hXhq*5|c dz=L/M1; % space step, make sure nonlinear<0.05
nep0<& " for m1 = 1:1:M1 % Start space evolution
]c4?-Vq%u u1 = exp(dz*i*(abs(u1).*abs(u1))).*u1; % 1st sSolve nonlinear part of NLS
7 .`Fe g. u2 = exp(dz*i*(abs(u2).*abs(u2))).*u2;
e0Zwhz, ca1 = fftshift(fft(u1)); % Take Fourier transform
ErnjIx: ca2 = fftshift(fft(u2));
mII7p Lb Q c2=exp(g.*dz).*(ca2+i*1*ca1.*dz); % approximation
-{n2^vvF c1=exp(g.*dz).*(ca1+i*1*ca2.*dz); % frequency domain phase shift
' ,$Uw|N u2 = ifft(fftshift(c2)); % Return to physical space
2 dg+R)% u1 = ifft(fftshift(c1));
*mwHuGbZed if rem(m1,J) == 0 % Save output every J steps.
`lygJI?H+{ U1 = [U1 u1]; % put solutions in U array
46OYO a U2=[U2 u2];
9%T~^V%T7 MN1=[MN1 m1];
l];w,(u{ z1=dz*MN1'; % output location
N8S !&*m end
<pyLWmO end
>>22: JI` hg=abs(U1').*abs(U1'); % for data write to excel
o_R<7o/d| ha=[z1 hg]; % for data write to excel
Z\c^C N t1=[0 t'];
Xf o3fW)s hh=[t1' ha']; % for data write to excel file
vkUXMMuf+e %dlmwrite('aa',hh,'\t'); % save data in the excel format
|, #DB figure(1)
5P'o+ Vwz waterfall(t',z1',abs(U1').*abs(U1')) % t' is 1xn, z' is 1xm, and U1' is mxn
7/C,<$Ep figure(2)
E0?R,+>&4 waterfall(t',z1',abs(U2').*abs(U2')) % t' is 1xn, z' is 1xm, and U1' is mxn
wiHGTaR {S[+hUl 非线性超快脉冲耦合的数值方法的Matlab程序 VAPR I\uM; nIc:<w] 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。
a_}k ^zw( 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
b/;!yO F ,6T F]6: $$'a gJ;jh7e@ % This Matlab script file solves the nonlinear Schrodinger equations
WRIOj Q: % for 3 cores nonlinear coupler. The output plot is shown in Fig.2 of
P5;n(E(19 % Youfa Wang and Wenfeng Wang, “A simple and effective numerical method for nonlinear
vf BIQfH % pulse propagation in N-core optical couplers”, IEEE Photonics Technology lett. Vol.16, No.4, pp1077-1079, 2004
f+3ico]f@ !'m
MGxkEb C=1;
9NzK1V0X M1=120, % integer for amplitude
n/] w! M3=5000; % integer for length of coupler
Fs+
CY N = 512; % Number of Fourier modes (Time domain sampling points)
5 @ c/,6l dz =3.14159/(sqrt(2.)*C)/M3; % length of coupler is divided into M3 segments, make sure nonlinearity<0.05.
}7L o}} T =40; % length of time:T*T0.
3X|7 R dt = T/N; % time step
ct o +W}k n = [-N/2:1:N/2-1]'; % Index
kD"BsL*6! t = n.*dt;
I'sq0^ ww = 4*n.*n*pi*pi/T/T; % Square of frequency. Note i^2=-1.
'?$N.lj$d w=2*pi*n./T;
B8=r^!jEL g1=-i*ww./2;
4S9hz g2=-i*ww./2; % w=2*pi*f*n./N, f=1/dt=N/T,so w=2*pi*n./TP=0;
VT@,RlB0 g3=-i*ww./2;
ui>0?O*G P1=0;
pk>p|q P2=0;
l rRRRR P3=1;
~%gO +qD P=0;
x{'3eJ^ 8 for m1=1:M1
b\
P6,s'( p=0.032*m1; %input amplitude
8)KA {gN} s10=p.*sech(p.*t); %input soliton pulse in waveguide 1
x JcM1>cT> s1=s10;
3P}^Wu s20=0.*s10; %input in waveguide 2
f S@V`"O6 s30=0.*s10; %input in waveguide 3
uDe%M s2=s20;
.@5Ro D[ o s3=s30;
W'98ue s% p10=dt*(sum(abs(s10').*abs(s10'))-0.5*(abs(s10(N,1)*s10(N,1))+abs(s10(1,1)*s10(1,1))));
'
\8|`Zb %energy in waveguide 1
76'@}wNnw p20=dt*(sum(abs(s20').*abs(s20'))-0.5*(abs(s20(N,1)*s20(N,1))+abs(s20(1,1)*s20(1,1))));
s8O.yL %energy in waveguide 2
E: 7R>. g p30=dt*(sum(abs(s30').*abs(s30'))-0.5*(abs(s30(N,1)*s30(N,1))+abs(s30(1,1)*s30(1,1))));
k_,wa]ws$ %energy in waveguide 3
bY@ S[ for m3 = 1:1:M3 % Start space evolution
A vh"(j s1 = exp(dz*i*(abs(s1).*abs(s1))).*s1; % 1st step, Solve nonlinear part of NLS
[\_#n5 s2 = exp(dz*i*(abs(s2).*abs(s2))).*s2;
JX hHitUD s3 = exp(dz*i*(abs(s3).*abs(s3))).*s3;
[c`u sca1 = fftshift(fft(s1)); % Take Fourier transform
'c[|\M!u sca2 = fftshift(fft(s2));
GS*Mv{JJ sca3 = fftshift(fft(s3));
%)t9b@c!} sc1=exp(g1.*dz).*(sca1+i*C*sca2.*dz); % 2nd step, frequency domain phase shift
jsp)e = sc2=exp(g2.*dz).*(sca2+i*C*(sca1+sca3).*dz);
O,D/& 0 sc3=exp(g3.*dz).*(sca3+i*C*sca2.*dz);
*X%dg$VcV s3 = ifft(fftshift(sc3));
xPcH]Gs^b s2 = ifft(fftshift(sc2)); % Return to physical space
{e/6iSpT s1 = ifft(fftshift(sc1));
3oo Tn-`{ end
FS+v YqwK p1=dt*(sum(abs(s1').*abs(s1'))-0.5*(abs(s1(N,1)*s1(N,1))+abs(s1(1,1)*s1(1,1))));
Bu{1^g: p2=dt*(sum(abs(s2').*abs(s2'))-0.5*(abs(s2(N,1)*s2(N,1))+abs(s2(1,1)*s2(1,1))));
pBR9)T\ n p3=dt*(sum(abs(s3').*abs(s3'))-0.5*(abs(s3(N,1)*s3(N,1))+abs(s3(1,1)*s3(1,1))));
r.~^h^c] P1=[P1 p1/p10];
%C1*`"Jb& P2=[P2 p2/p10];
;$FpxurX P3=[P3 p3/p10];
^.Xom~ P=[P p*p];
9im<J' end
^q@ 6((O figure(1)
Fcp8RBq plot(P,P1, P,P2, P,P3);
IncHY?ud< fGf C[DuY 转自：
http://blog.163.com/opto_wang/
