40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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Message ID: 2379     Entry time: Mon Jul 29 18:01:12 2019
Author: ScottA and anchal 
Type: DailyProgress 
Category: RFAM 
Subject: RFAM Set-up and Measurement  

Our previous plan turned out to be ineffective due to the mirror not transmitting all of the P polarization, but only a fraction. We now used the PBS within the faraday isolator (FI) as a pickoff, and rotate the HW plate at the input to control the power reflected. When the HW plate is maximized for transmission through the FI, I measured 13.4 mW into the FI, 12.00 mW at the output and 1.18 mW picked off. I then used a mirror to steer the picked-off beam onto the 1811 new focus photodetector. Using the DC coupled output I maximized the output on an o-scope, which was at the level of 400 mV. The AC output was then connected to the HP4395A analyzer from which the data was taken. 

  • In the first graph, we see a peak at 14.75 MHz from a previous EOM, as well as its second harmonic at 29.5 MHz. The third peak is the RAM due to the 37 MHz EOM, which we wish to suppress.
  • In the second graph, we see the 37 MHz peak as well as two smaller peaks around it, but we do not know what is causing these peaks.
  • In the third graph we see the same as before but zoomed in more and with smaller bandwidth.

Edit: I have now put a focusing mirror with a focal length of 5cm before the PD, the o-scope now reads 3.41 V.  A pdf of the layout with these updates can be found at https://nodus.ligo.caltech.edu:30889/ATFWiki/lib/exe/fetch.php?media=main:experiments:psl:ctn_optical_layout.pdf

 

Attachment 1: RAM_Measurement_data.zip  158 kB  Uploaded Mon Jul 29 19:12:07 2019
Attachment 2: RAM_37MHz_7_29_2019.pdf  37 kB  Uploaded Mon Jul 29 19:12:13 2019  | Hide | Hide all
RAM_37MHz_7_29_2019.pdf RAM_37MHz_7_29_2019.pdf RAM_37MHz_7_29_2019.pdf
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