classname FoldedDoubleCavity # parameters const Pin 1 # input power const Lprc 6.752 # power recycling cavity length const d_BS_PR3 0.401 # folding mirror distances const d_PR2_PR3 2.081 const d_PRM_PR2 1.876 const c 299792458 # speed of light const fmod 5*c/(4*Lprc) # modulation frequency, matched to Lprc const Larm 38 # arm cavity length const Tpr 0.0575 # PRM recycling mirror transmission const Titm 0.014 # ITM transmission const Tetm 10e-6 # ETM transmission const Rcpr 115.9 # PRM radius of curvature (matched to cavity mode) const Rcitm Inf # ITM radius of curvature const Rcetm 57.4 # ETM radius of curvature # laser source and phase modulator laser l nL P=Pin modulator eom nL nM f=fmod m=0.2 type=pm space s1 nM nPRM1 L=1 # recycling mirror and cavity (with folded mirrors) mirror PRM nPRM1 nPRM2 T=Tpr Rc=-Rcpr space PRC1 nPRM2 nPR2_1 L=d_PRM_PR2 phi=pi/2 beamsplitter PR2 nPR2_1 nPR2_2 nPOP nPR2_4 T=1e-6 space PRC2 nPR2_2 nPR3_1 L=d_PR2_PR3 beamsplitter PR3 nPR3_1 nPR3_2 nPR3_3 nPR3_4 R=1 space PRC3 nPR3_2 nI1 L=Lprc-d_PRM_PR2-d_PR2_PR3 # arm cavity mirror ITM nI1 nI2 T=Titm Rc=-Rcitm space CAV nI2 nE1 L=Larm mirror ETM nE1 nE2 T=Tetm Rc=Rcetm cavity CAV # power meters power RefDC nPRM1 from=PRM power RecDC nPRM2 from=PRM power CavDC nI2 from=ITM power TraDC nE2 from=ETM # QPDs space sPOP nPOP nPOP2 L=1 beamsplitter bsPOP nPOP2 nPOP3 nPOP4 nPOP5 R=0.5 quadrant QPD_POPall nPOP3 from=bsPOP space sFilt nPOP4 nPOP6 L=0 filter filt nPOP6 nPOP7 bw=1000 quadrant QPD_POPcar nPOP7 from=filt # drives driver aITM ITM driver aETM ETM driver aPRM PRM driver aPR2 PR2 driver aPR3 PR3