% This program is an example to use thin film model. The design if a

% broadband reflector for the visible region of design.

% Data resource: Figure 4-27 in "Optical thin film"

% initial program

clear all;

close all;

um = 1e-6;

nm = 1e-9;

% define admittance for medium

Air = 1;

Glass = 1.52;

% define the reference wavelength and thickness

lambda_f = 880*nm;

% define visible region of light

lambda = linspace(200,1500,501)*nm;

% define thin film structure

y_inc = Air; % incident medium admittance

y_sub = Air; % substrate medium admittance

theta = 60; % in degree

%d = film thickness

%y = index for d, n-ik   

d=[100*nm;200*nm;300*nm;];

y=[1.25;1.5;1.75;];

%rho= sqrt(R), complex reflection coefficient

%tao= sqrt(T), complex reflection coefficient

%  y_inc|y|y_sub 共三層

for ii=1:length(lambda),

[rho(ii),tao(ii),R(ii),T(ii)] =multilayer_s(d,y,y_inc,y_sub,lambda(ii),theta);

end

% plot the result

figure;hold on;

plot(lambda/nm,R*1,'-k','LineWidth',3);

plot(lambda/nm,T*1,'-k','LineWidth',3);

title('A broadband reflector for the visible region');

xlabel('Wavelength(nm)');

ylabel('Reflectance(%)');

%axis([350 850 0 105]);

grid on;

for ii=1:length(lambda),

[rho2(ii),tao2(ii),R2(ii),T2(ii)] =multilayer_p(d,y,y_inc,y_sub,lambda(ii),theta);

end

% plot the result

figure;hold on;

plot(lambda/nm,R2*1,'-k','LineWidth',3);

plot(lambda/nm,T2*1,'-k','LineWidth',3);

title('A broadband reflector for the visible region');

xlabel('Wavelength(nm)');

ylabel('Reflectance(%)');

%axis([350 850 0 105]);

grid on;