:PROPERTIES:
:ID:       d7630955-6ca9-4de7-9770-2d50d4847bcd
:END:
#+title: Fitting Ringdown

* Fitting transients
- one can solve the equation of motion for when a mode is in the
  steady state and the laser is suddenly switched. one obtains a
  decaying oscillation which can be fitted to the data.
- this works ok, when the system /was/ in the steady state before the jump
- see [[file:scripts/transients_without_amplification.py]]
- we obtain \(γ\approx\SI{2.2}{\kilo\hertz}\) but this can vary a lot
- the detuning frequency seems to be completely off

* Failure of the steady state

On the right peak on can see that there might be something fish going
on. This is ~data/24_05_24/nice_transient2~.
[[file:figures/non_steady.png]]

* Weird Oscillations                                                 :ATTACH:
- when turning on the amp while the laser is running we get some
  oscillations at \(\sim \SI{40}{\kilo\hertz}\) which is a period of
  \(\SI{25}{\micro\second}\). this is 500 times roundrip time :(). I
  thought it might be a wave packet traveling around the loop, i.e
  multiple modes together...

[[attachment:osci_closeup.png][osci_closeup.png]]
[[attachment:osci_far.png][osci_far.png]]
[[attachment:cleaned.png][cleaned.png]]
- it isn't close to the fsr though...
- fitting a sine to that gives pretty much the same, as does an fft
  [[attachment:cleaned_fit.png][cleaned_fit.png]]

- it is pretty constant over all steps in [[file:data/09_05_24/Nicely_hybridised_2 2024,05,09, 15h57min00sec/][data]] as can be ascertained
  from [[file:scripts/weird_oscillations.py][this script]]
- these are also present w/o the amp cutout!
[[attachment:osci_without.png][osci_without.png]]