Comparing the sensitivity before and after WE mirror cleaning, see attachment with different curves:

a) red before cleaning, no shift on WE mirror

b) blue before cleaning, shift on WE mirror: optical gain is about 20% better than in a)

c) purple after cleaning, no shift on WE mirror: optical gain is about 5÷6% better than in a)

d) green after cleaning, shift on WE mirror: optical gain is similar as in b)

A quick conclusion is that:

1) the broadband ~1/f^2 noise between 50 and 70 Hz, that was present before cleaning and did not depend on optical gain, is not present anymore

2) the 3 Hz comb, that was present before cleaning and whose ampltude did not depend on optical gain, is not present anymore

3) the broadband (1/f^2/3?) noise between 100 Hz and 200 Hz is scaling with the optical gain; with similar optical gain, it's roughly the same before and after cleaning.