comparesemianalysis_discrete_fft.asv

通过计算晶体结构来确定其光谱分布

%CompareSemiAnalysis_Discrete.m
%Ref:Linfang Shen, Sailing He, and Sanshui Xiao, Large absolute band gaps
%in two-dimensional photonic crystals formed by large dielectric pixels,
%Physical Review B 66, 165315-1->-6 (2002)
clear;
clear global;
close all;

cnh=6;                  %Half number of pixels in one cell
pw=1;                   %Width of pixel
cn=2*cnh;               %Number of pixles in one cell
cw=cn*pw;               %Width of cell
cwh=cnh*pw;             %Half width of cell
ebxn=rand(cwh);         %One fourth of a cell

HN=cwh;              
%Half number of Fourier coefficients
N=cw;
%Total number of Fourier coefficients

fx=(-HN:HN-1);
fy=fx;

FS=zeros(N,N,3);
for flag=1:3
    for n=-HN:HN-1
        for m=-HN:HN-1
            FS(HN+n+1,HN+m+1,flag)=ebxn_2D_FS(ebxn,pw,cw,m,n,flag);
        end
    end
end
hN=0;
hN=hN+1;
figure(hN);
for m=1:3
    subplot(2,3,m);
    plot(fx,real(FS(HN,:,m)));
    str=sprintf('Real %d',m);
    title(str);
    subplot(2,3,3+m);
    plot(fx,imag(FS(HN,:,m)));
    str=sprintf('Imagery %d',m);
    title(str);
end

t=cat(2,ebxn,fliplr(ebxn));
ebxn_1=cat(1,t,flipud(t));
clear t;
tN=max(size(ebxn_1));
FS_1=zeros(tN,tN,3);
t=zeros(tN);
et=1./ebxn_1;

%Model 1 FFT
for m=1:tN
    t(:,m)=fft(et(:,m));
end
t=1./t;
for m=1:tN
    FS_1(m,:,1)=fft(t(m,:));
end

%Model 2 FFT
for m=1:tN
    t(m,:)=fft(et(m,:));
end
t=1./t;
for m=1:tN
    FS_1(:,m,2)=fft(t(:,m));
end

%Model 3 FFT
FS_1(:,:,3)=fft2(ebxn_1);

for m=1:3
    FS_1(:,:,m)=fftshift(FS_1(:,:,m));
end

hN=hN+1;
figure(hN);
for m=1:3
    subplot(2,3,m);
    plot(fx,real(FS_1(HN,:,m)));
    str=sprintf('Real %d',m);
    title(str);
    subplot(2,3,3+m);
    plot(fx,imag(FS(HN,:,m)));
    str=sprintf('Imagery %d',m);
    title(str);
end
disp('CompareSemiAnalysis_Discrete ends');