volker.quetschke@LIGO.ORG - posted 17:14, Wednesday 01 August 2012 (3693)
Frequency dependent sideband strength in H1 EOM
[Michael R., Volker Q.]
Following the measurements at LLO we measured the frequency dependent sideband generation around the resonant frequencies. See here for the LLO measurements.
The table below shows the sideband height as measured with a OSA on the PSL table. The frequency is the modulation frequency in MHz. All three modulator inputs were driven with 10Vpp (in 50ohm).
| Carrier (V): | 2.15 | 2.10 | 2.14 | |||||||
| Frequency | SB (mV) | m | Frequency | SB (mV) | m | Frequency | SB (mV) | m | ||
| 8.90 | 21 | 0.20 | 23.80 | 7 | 0.12 | 44.80 | 14 | 0.16 | ||
| 8.95 | 28 | 0.23 | 23.85 | 11 | 0.14 | 44.90 | 15 | 0.17 | ||
| 9.00 | 37 | 0.26 | 23.90 | 13 | 0.16 | 45.00 | 18 | 0.18 | ||
| 9.05 | 55 | 0.32 | 23.95 | 17 | 0.18 | 45.10 | 24 | 0.21 | ||
| 9.10 | 82 | 0.39 | 24.00 | 18 | 0.19 | 45.20 | 30 | 0.24 | ||
| 9.15 | 99 | 0.43 | 24.05 | 17 | 0.18 | 45.30 | 37 | 0.26 | ||
| 9.20 | 90 | 0.41 | 24.10 | 11 | 0.14 | 45.40 | 45 | 0.29 | ||
| 9.25 | 66 | 0.35 | 24.15 | 10 | 0.14 | 45.50 | 53 | 0.31 | ||
| 9.30 | 44 | 0.29 | 24.20 | 9 | 0.13 | 45.60 | 53 | 0.31 | ||
| 9.35 | 28 | 0.23 | 24.25 | 7 | 0.12 | 45.70 | 50 | 0.31 | ||
| 9.40 | 19 | 0.19 | 24.30 | 5 | 0.10 | 45.80 | 40 | 0.27 | ||
| 45.90 | 30 | 0.24 | ||||||||
| 46.00 | 22 | 0.20 | ||||||||
| 46.10 | 17 | 0.18 |
The sideband strength is well centered around the target frequencies of 9.1MHz and 45.5MHz. The 24.1MHz modulation is slightly off by 100kHz, but I did not want to risk to change the other two frequencies while trying to change the not so important 24.1MHz frequency.