This plot was created in matlab with the following code:

   ti = 0:.01:pi/2; %incidence angle
   n1 = 1; n2 = 1.5; %refractive indices
   tt1 = asin(n1/n2*sin(ti)); %transmission angle
   tt2 = asin(n2/n1*sin(ti)); %transmission angle from n2 to n1
   Rs(1,:) = (sin(ti-tt1)./sin(ti+tt1)).^2;
   Rp(1,:) = (tan(ti-tt1)./tan(ti+tt1)).^2;
   Rs(2,:) = abs(sin(ti-tt2)./sin(ti+tt2)).^2;
   Rp(2,:) = abs(tan(ti-tt2)./tan(ti+tt2)).^2;
   figure(1); clf;
   for fig = 1:2
       %subplot(1,2,fig);
       axes('Position',[.07+.48*(fig-1) .14 .42 .77])
       plot(ti*180/pi,100*Rs(fig,:),'linewidth',2)
       hold on;
       plot(ti*180/pi,100*Rp(fig,:),'r','linewidth',2)
       xlim([0 90]); ylim([0 100]);
       set(gca,'XTick',0:10:90);
       set(gca,'YTick',0:10:100);
       %set(gca,'xminortick','on');
       xlabel('Angle of incidence $\theta_i$ ($^\circ$)','interpreter','latex');
       set(gca,'fontname','times','fontsize',8);
       legend({'$R_\textrm{s}$','$R_\textrm{p}$'},'interpreter','latex',...
           'location','NW','fontsize',10);
       legend boxoff
       if fig == 1
           ylabel('Reflection coefficient (\%)','interpreter','latex','fontsize',10);
           title('$n_1=1,\; n_2=1.5$','interpreter','latex','fontsize',10);
           hold on;
           b = atan(n2/n1)*180/pi;
           plot([1 1]*b,[0 100],'linestyle',':','color','black','linewidth',1);
           text(b-1,70,'Brewsters angle','interpreter','latex',...
               'Rotation',90,'VerticalAlignment','bottom',...
               'HorizontalAlignment','center','fontsize',10)
       else
           title('$n_1=1.5,\; n_2=1$','interpreter','latex','fontsize',10);
           hold on;
           c = asin(n1/n2)*180/pi;
           plot([1 1]*c,[0 100],'linestyle',':','color','black','linewidth',1);
           text(c+2,70,'Critical angle','interpreter','latex',...
               'Rotation',90,'VerticalAlignment','top',...
               'HorizontalAlignment','center','fontsize',10)
           text((90+c)/2,40,[' Range of total' char(10) 'internal reflection'],'interpreter','latex',...
               'HorizontalAlignment','center','fontsize',10)
       end
   end

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