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