Follow up analysis of the OMC scan by Dan (ALOG entry13660)
I believe this was done with a single bounce of ITMX.
ITMY had an oplev issue at the time as you can seen in https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13654
Frequency calibration
Calibratre data points using 0th- to 3rd-order carrier resonances and 0th- and 2nd-order sideband resonances as a frequency reference
Interpolate the frequency calibration by 11th order polynomials (see attachment "OMC_mode_scan_freq_calib.pdf")
Mode identification
Once the frequency is calibrated, the modes can be identified. As the beam is not filtered, it contains all of the sidebands and the sidebands of the sidebands including their higher-order spatial modes. (Attachment "OMC_modes.png" or "OMC_modes.pdf")
In the figure "USB/LSBn" indicates nth-order higher-order mode for upper or lower sidebands for 45MHz modulation.
"usb/lsb" indicates upper or lower sidebands for 9MHz modulation.
"2xUSB0" and "2xUSB0" means 2nd-order modulation sidebands for the 45MHz modulation (i.e. 90MHz sidebands).
Peak fitting
Peak heights of most of the modes are fitted (by hand). (Attachment "OMC_scan_LHO.pdf")
The decomposition of the modes are listed at the end of this entry
Mode matching
From the mode decomposition, the mode matching of the carrier is 0.86 +/- 0.01
Modulation depth
From the ratio of the sideband photocurrent and the carrier photocurrent, the modulation depth for each modulation was estimated
Modulation depth for f1 (9MHz): 0.198+/- 0.006
Modulation depth for f2 (45MHz): 0.305+/-0.003
| Carrier | |
| Order | mA |
| 0 | 13.13 |
| 1 | 0.088 |
| 2 | 1.65 |
| 3 | 0.028 |
| 4 | 0.25 |
| 5 | 0.012 |
| 6 | 0.07 |
| 7 | 0.008 |
| 8 | 0.018 |
| Upper sidebands (45MHz) | |
| Order | mA |
| 0 | 0.3105 |
| 1 | 0.0024 |
| 2 | 0.036 |
| 3 | 0.0004 |
| 4 | 0.005 |
| Lower sidebands (45MHz) | |
| Order | mA |
| 0 | 0.313 |
| 1 | 0.002 |
| 2 | 0.036 |
| 3 | 0.0004 |
| 4 | 0.0065 |
| 2nd order Upper sidebands (90MHz) | |
| Order | mA |
| 0 | 0.0025 |
| 1 | 0.00002 |
| 2 | 0.00075 |
| 2nd order Lower sidebands (90MHz) | |
| Order | mA |
| 0 | 0.0025 |
| 1 | 0.00002 |
| 2 | 0.00075 |
| Upper sidebands (9MHz) | |
| Order | mA |
| 0 | 0.13 |
| 1 | 0.001 |
| 2 | 0.015 |
| 3 | 0.0008 |
| 4 | 0.0035 |
| Lower sidebands (9MHz) | |
| Order | mA |
| 0 | 0.13 |
| 1 | 0.001 |
| 2 | 0.015 |
| 3 | 0.0008 |
| 4 | 0.0035 |
| Sidebands of sidebands | |
| (+/-9MHz+/-45MHz) | mA |
| -54MHz | 0.003 |
| -36MHz | 0.003 |
| 36MHz | 0.003 |
| 54MHz |
0.003 |
| Carrier TEM00 | 13.13 | mA | |
| Carrier TEMnm | 2.12 | mA | |
| Sideband | 1.03 | mA | |
| Mode matching | 0.86 | ||
