[Peter K., Alexa, Paul, Mackenzie]

(Written by Mackenzie, on Paul's login)

This morning we went into the PSL to set up the RFAM measurement and try to finalize the IO table layout.

We found that IO_AB_W1, which sends the beam to IO_AB_PD1 and IO_AB_PD3, was substituted previously with a temporary 1" HR mirror, so we located and installed the correct AR 2" window. We placed IO_AB_PD3 in transmission of IO_AB_W1 and placed IO_AB_PD1 (the RF 1811 PD) in reflection of the window. IO_AB_PD3 is saturating right now even at the lowest gain setting, so we'll have to attenuate that beam more somehow. 

Regarding the RFAM measurement, we were able to see the carrier with 45 MHz and 9 MHz sidebands on the OSA. The resolution was not great, and some of the sidebands were lost in the noise floor. Volker had previously performed this measurement, but needed an amplifier to boost the signal onto the EOM to see the sidebands well. We intend to go back in later today or tomorrow with an amplifier and try again. When we slowed the OSA scan down to try to resolve the peaks better, we found that the carrier peak was quite distorted (see attached pic). Maybe something to do with PZT non-linearity, we're not sure yet. Another attached pic shows the visible 45MHz sidebands along with two carrier FSRs. 

We looked at the RFPD spectrum, and were only able to see 9MHz sidebands. For some reason neither the 24MHz or 45MHz sidebands were visible. We had assumed RFAM/PM would be consistent between different sideband frequencies, but this doesn't seem to be the case. Again, we will know better once we get the amplifier in place.