40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Entry  Thu Jun 20 17:23:40 2013, Chloe, DailyProgress, ECDL, Noise Calculations saito.pdfpsd_noise.png
    Reply  Fri Jun 21 16:47:30 2013, Chloe, DailyProgress, ECDL, Noise Calculations Noise.pdf
       Reply  Mon Jun 24 11:14:04 2013, Chloe, DailyProgress, ECDL, Noise Calculations Noise.pdf
          Reply  Mon Jun 24 17:48:30 2013, Chloe, DailyProgress, ECDL, Noise Calculations Noise.pdf
             Reply  Tue Jun 25 14:14:17 2013, rana, DailyProgress, ECDL, Noise Calculations 
                Reply  Tue Jun 25 17:51:34 2013, Chloe, DailyProgress, ECDL, Noise Calculations Noise2.pdf
                   Reply  Wed Jun 26 17:13:21 2013, Chloe, DailyProgress, ECDL, Noise Calculations Noise2.pdf
                      Reply  Fri Jun 28 14:52:11 2013, tara, Notes, ECDL, laser noise requirement for locking to a refcav 
                      Reply  Sun Jun 30 22:58:45 2013, Chloe, DailyProgress, ECDL, Noise Calculations compare_experiments.pngcompare_diodes.pngcompare_gratings.pngcompare_length.png100_0068.JPG
Message ID: 1214     Entry time: Wed Jun 26 17:13:21 2013     In reply to: 1211     Reply to this: 1216   1219
Author: Chloe 
Type: DailyProgress 
Category: ECDL 
Subject: Noise Calculations 

Today I spent the morning searching the literature on Web of Knowledge to see if anyone had ways to reduce the noise level of an ECDL further by tweaking the parameters of the Littrow configuration (our current plan, where first order beams coming off the diffraction grating go back into the laser diode). It may be worth examining configurations with more mirrors to lengthen the cavity, but otherwise my search was not particularly helpful. We may need to start looking at the Littman-Metcalf configuration??? This theoretically reduces linewidths more but has lower efficiency. The diffraction grating is immovable, and an adjustable mirror is used instead to reflect light back onto the diffraction grating. 

Tara got me the information for me to calculate how a servo would reduce the noise of the ECDL further. I worked most of the afternoon to understand the principle behind the feedback, and ran calculations after searching the literature for reasonable numbers. Using a piezoactuator, we can reduce the noise at low frequencies, but it does not solve our problem at high frequencies (above 10 MHz), where there is essentially no noise reduction. See the attached pdf with the updates included (pages 5-8). 

Tomorrow I will see if I can find a piezoactuator that has a large actuator gain, which would cause more noise reduction at higher frequencies. Otherwise, building an ECDL will not be very useful for us to use at LIGO... 

Attachment 1: Noise2.pdf  179 kB  | Hide | Hide all
Noise2.pdf Noise2.pdf Noise2.pdf Noise2.pdf Noise2.pdf Noise2.pdf Noise2.pdf Noise2.pdf
ELOG V3.1.3-