It was found that the transmitted light power from the arm cavity has decreased, along with a decrease in the POP power. To investigate the cause, we examined the correlation between the transmitted light power from the arm cavity during the locked state and the amplitude of the pulse during the scan of both single cavities before PRMI locking, in order to determine whether clipping at the arm transmission port was responsible for the power reduction.
As shown by the blue and red plots. In the figure below, no strong correlation was observed, suggesting that clipping at the arm transmission port is unlikely to be the cause.
It is suspected that there may be losses both in the power recycling cavity and in the arm cavities.
Calculations of each loss are currently underway to investigate this possibility.
