Question regarding parameter given for Task A in hackathon

365  Aditi Borse  

How is the power recycling cavity length defined? There are so many optical elements in the PRM block.

One comment on “Question regarding parameter given for Task A in hackathon”

  1. Hi Aditi,

    I assume you refer to this following part of the kat code:

    %%% FTblock PRC
s sPRCin 0.4135 nHAM2out nPRM1
m1 PRM 0.03 8.5e-06 0.007 nPRM1 nPRM2
attr PRM Rcx 11.009
attr PRM Rcy 11.009
s lp1 16.610426383062517 nPRM2 nPR2a
bs1 PR2 0.00025 3.75e-05 0.0 -0.79 nPR2a nPR2b nPOP nAPOP
attr PR2 Rcx -4.545
attr PR2 Rcy -4.545
s lp2 16.1647 nPR2b nPR3a
bs1 PR3 0.0 3.75e-05 0.0 0.615 nPR3a nPR3b dump dump
attr PR3 Rcx 36.027
attr PR3 Rcy 36.027
s lp3 19.5381 nPR3b nPRBS
s sIO 0.0 nLaserOut nFI1
dbs FI nFI1 nFI2 nHAM2out nREFL
%%% FTend PRC

    The length of the power recycling cavity is the distance between the power recycling mirror (in this case the m1 named PRM) and the arm cavity ITMs. As you can see, the total length has contributions from more than one space (lp1, lp2, lp3). Also remember that surfaces (e.g. mirrors) are treated as infinitely thin so it’s only the space lengths that matter. Note that the spaces between the beam splitter and ITMs are defined in later blocks (FTblock Yarm and FTblock Xarm), and also contribute to the power recycling cavity length. You’ll see that the spaces between the beam splitter and ITMX and ITMY are slightly different – think how you might deal with that.

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