%Check for accidental resonances of HOM in the arms (maybe due to %sidebands). At the moment there is only data for the y arm. clear all close all clc %Stuff one might change often modeorder = 0:5; % Look for TEMmn modes where m,n run over modeorder Nfsr = -100:100; % Number of FSRs to look at range = [-0.3e6 0.3e6]; % Frequncies of interest [Hz] L = 38.6462; %Arm length Koji's measurement [m] - Elog #801 R1 = inf; % ITM ROC R2x = 56.1620; % ETM ROC in the `m' direction [m] - Elog #802 R2y = 57.3395; % ETM ROC in the `n' direction [m] - Elog #802 f166 = 165.977195e6; % fmod2 [Hz] f33 = 33.195439e6; % fmod1 [Hz] %Speed of light c = 299792458; %Free spectral range FSR = c/(2*L); %Wavelength lambda = 1064e-9; %Frequncies of interest npts = 4000; f = linspace(range(1), range(2), npts); %Mirror parameters T1 = 0.005; T2 = 1e-5; Ref1 = 1-T1; Ref2 = 1-T2; r1 = sqrt(Ref1); r2 = sqrt(Ref2); g1 = 1-L/R1; g2x = 1-L/R2x; g2y = 1-L/R2y; %Arm resonance Pstored = T1./(1-2*r1*r2*cos(2*(2*pi*f/c)*L)+Ref1*Ref2); %Resonance frequencies %Higher order mode frequency shift delfx = acos(sqrt(g1*g2x))/pi; delfy = acos(sqrt(g1*g2y))/pi; fres = []; f00 = []; modeindex = []; labels2 = []; for q = Nfsr f00 = [f00 q*FSR]; % TEM00 resonances for m = modeorder for n = modeorder modeindex = [modeindex m+n]; % m+n of modes labels2 = [labels2; m n]; % labels for plot fres = [fres (q+m*delfx+n*delfy)*(c/(2*L))]; % resonance frequncies end end end labels2 = cellstr(int2str(labels2)); %labels for plot %To get the sidebands can just add +/-166,33 - this is an approximation %Matrix for plotting lines linemat = repmat(fres,2,1); TEM00mat = repmat(f00,2,1); %To get the sidebands can just add +/-166,33 - this is an approximation f00166pmat = TEM00mat+f166; f00166mmat = TEM00mat-f166; fres166pmat = linemat+f166; fres166mmat = linemat-f166; f0033pmat = TEM00mat+f33; f0033mmat = TEM00mat-f33; fres33pmat = linemat+f33; fres33mmat = linemat-f33; %Scale lines nicely height = 1./ repmat(modeindex,2,1).^2; [aa, bb] = find(height==Inf); height(aa, bb) = 0; %Normalise peak power gain to one Pstored = Pstored/max(Pstored); %----------------Make Plot------------------------------------------ figure(1) semilogy(f*1e-6,Pstored,'k') title('Sideband HOM resonances in the arms') xlim(range*1e-6) line(TEM00mat*1e-6, repmat([1e-6 1]',1,size(TEM00mat,2)),'Color','Black') line(linemat*1e-6, repmat([1e-6 1]',1,size(linemat,2)).*height,'Color','Black') line(f00166pmat*1e-6, repmat(get(gca,'Ylim')',1,size(TEM00mat,2)),'Color','Blue','LineWidth',4) line(fres166pmat*1e-6, repmat([1e-6 1]',1,size(linemat,2)).*height,'Color','Blue') line(f00166mmat*1e-6, repmat(get(gca,'Ylim')',1,size(TEM00mat,2)),'Color','Green','LineWidth',4) line(fres166mmat*1e-6, repmat([1e-6 1]',1,size(linemat,2)).*height,'Color','Green') line(f0033mmat*1e-6, repmat(get(gca,'Ylim')',1,size(TEM00mat,2)),'Color','Red','LineWidth',4) line(fres33mmat*1e-6, repmat([1e-6 1]',1,size(linemat,2)).*height,'Color','Red') line(f0033pmat*1e-6, repmat(get(gca,'Ylim')',1,size(TEM00mat,2)),'Color','Magenta','LineWidth',4) line(fres33pmat*1e-6, repmat([1e-6 1]',1,size(linemat,2)).* ... height,'Color','Magenta') set(gcf,'Color','White','units','normalized','outerposition',[0 0 1 1]); %Make text vectors for labels scaling = height(1,:); x = fres*1e-6; [ind] = find(abs(x)>range(2)*1e-6); x(ind) = 2*range(2); y = ones(length(x),1)'.*scaling; text(x,y,labels2,'Rotation',90) x = (fres+f166)*1e-6; [ind] = find(abs(x)>range(2)*1e-6); x(ind) = 2*range(2); y = ones(length(x),1)'.*scaling; labels = (modeindex)'; text(x,y,labels2,'Color','Blue','Rotation',90) x = (fres-f166)*1e-6; [ind] = find(abs(x)>range(2)*1e-6); x(ind) = 2*range(2); y = ones(length(x),1)'.*scaling; labels = (modeindex)'; text(x,y,labels2,'Color','Green','Rotation',90) x = (fres+f33)*1e-6; [ind] = find(abs(x)>range(2)*1e-6); x(ind) = 2*range(2); y = ones(length(x),1)'.*scaling; labels = (modeindex)'; text(x,y,labels2,'Color','Magenta','Rotation',90) x = (fres-f33)*1e-6; [ind] = find(abs(x)>range(2)*1e-6); x(ind) = 2*range(2); y = ones(length(x),1)'.*scaling; labels = (modeindex)'; text(x,y,labels2,'Color','Red','Rotation',90) text(0.9*range(1)*1e-6,5,'Carrier') text(.45*range(1)*1e-6,5,'+33','color','Magenta') text(0,5,'-33','color','Red') text(.45*range(2)*1e-6,5,'+166','color','Blue') text(.9*range(2)*1e-6,5,'-166','color','Green') grid xlabel('Frequency/ MHz') ylabel('Normalised cavity Power Gain') ylim([1e-6 10*max(Pstored)])