coupler_even_odd.m

强大的计算电磁场本征函数与本征模的程序

% This example shows how to calculate the even and odd modes
% of two coupled waveguides, using the semivectorial modesolver

% Refractive indices:
n1 = 3.34;          % Lower cladding
n2 = 3.44;          % Core
n3 = 1.00;          % Upper cladding (air)

% Layer heights:
h1 = 2.0;           % Lower cladding
h2 = 1.3;           % Core thickness
h3 = 0.5;           % Upper cladding

rh = 0.7;           % Ridge height
rw = 2.0;           % Ridge full-width
d = 3.0;            % center-to-center separation
side = 2.5;         % Space on side

dx = 0.0125;        % grid size (horizontal)
dy = 0.0125;        % grid size (vertical)

lambda = 1.55;      % wavelength
nmodes = 1;         % number of modes to compute

fprintf (1,'generating index mesh...\n');
[x,y,xc,yc,nx,ny,eps] = coupler([n1,n2,n3],[h1,h2,h3],rh,d,rw,side,dx,dy);

% First, we calculate the symmetric mode
boundary = '000S';  

fprintf (1,'solving for symmetric eigenmodes (TE) ... '); t = cputime;
[Ex1,neff1] = svmodes (lambda, n2, nmodes, dx, dy, eps, ...
                       boundary, 'EX'); 
fprintf (1,'done (cputime = %7.3f)\n', cputime-t);
fprintf(1,'neff(1) = %7.5f\n',neff1);

% First, we calculate the symmetric mode
boundary = '000A';  

fprintf (1,'solving for symmetric eigenmodes (TE) ... '); t = cputime;
[Ex2,neff2] = svmodes (lambda, n2, nmodes, dx, dy, eps, ...
                       boundary, 'EX'); 
fprintf (1,'done (cputime = %7.3f)\n', cputime-t);
fprintf(1,'neff(2) = %7.5f\n',neff2);

subplot(211);
contourmode(xc,yc,Ex1(:,:,1),1,3,45,'Ex (Symmetric TE mode)');
v = xlim;
line(v,[h1,h1]);
line([v(1),(d-rw)/2,(d-rw)/2,(d+rw)/2,(d+rw)/2,v(2)], ...
     [h1+h2-rh,h1+h2-rh,h1+h2,h1+h2,h1+h2-rh,h1+h2-rh]);

subplot(212);
contourmode(xc,yc,Ex2(:,:,1),1,3,45,'Ex (Antisymmetric TE mode)');
v = xlim;
line(v,[h1,h1]);
line([v(1),(d-rw)/2,(d-rw)/2,(d+rw)/2,(d+rw)/2,v(2)], ...
     [h1+h2-rh,h1+h2-rh,h1+h2,h1+h2,h1+h2-rh,h1+h2-rh]);