2001011820209.m

可以实现激光谐振腔的自再现；有利于了解激光腔的原理

clear
int16 number;
int16 m1;
int16 n1;
int16 m2;
int16 n2;
double expl;
double u20;
double u10;
wavel=1.55e-2;
k=2*pi/wavel;
N=21;                                                   % N 必须为奇数
M=(N+1)/2;
L=100000;
u1=ones(N,N);
u2=zeros(N,N);
Bmn=ones(N,N);
u1bf=zeros(N,N);
Bmn=u1-u1bf;
Bmn=abs(Bmn);
maxBmn=max(Bmn);
maxBmn=max(maxBmn);

number=0;

while(max(maxBmn)>7.0e-16)                          
 
 for m2=1:N                                          % 由u1计算u2                            
    for n2=1:N
        
        u2(m2,n2)=0;
        for m1=1:N
            for n1=1:N
                expl=exp(-i*k*((m1-m2)*(m1-m2)+(n1-n2)*(n1-n2))/2/L);
                u2(m2,n2)=u2(m2,n2)+i*k*u1(m1,n1)*exp(-i*k*L)*expl/L/pi/2;
            end
        end
       
    end
end
u20=u2(M,M);                                        % 归一化
u2=u2/u20;                                
  


u1bf=u1;                                             %由u2计算u1
for m1=1:N                                 
    for n1=1:N
        u1(m1,n1)=0;
        for m2=1:N
            for n2=1:N
                expl=exp(-i*k*((m1-m2)*(m1-m2)+(n1-n2)*(n1-n2))/2/L);
                u1(m1,n1)=u1(m1,n1)+i*k*u2(m2,n2)*exp(-i*k*L)*expl/L/pi/2;
            end
        end
    end
end

u10=u1(M,M) ;                                       %归一化
u1=u1/u10; 

Bmn=u1-u1bf;                                        %u1前后对比
Bmn=abs(Bmn); 
maxBmn=max(Bmn);
maxBmn=max(maxBmn);

number=number+1;

end
number;

u1bf=abs(u1);                                     %作图
z1=angle(u1);
x=[1:N];
y=[1:N];
z=u1bf(x,y);

subplot(3,3,1);
mesh(z);
subplot(3,3,2);
mesh(z1);