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--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 17:48, 22 July 2014 (CDT)
Re: SHG Locking stability and laser tuning. It seems like we're making a little progress understanding what affects the shape of the error signal and positions of the cavity modes due to the different polarizations.
*When the different polarization modes are piled on top of each other, we get a crappy error signal and our lock is not very stable. This can happen when we change the cavity length somehow or change the temperature which also changes the cavity lengths for the two polarizations.
*The error signal does not have to look perfect/textbook, i.e. the modes don't have to be very well separated but they do have to be distinct. It appears it's not necessary to stress getting the modes well separated.
*There are wiggles at 100Hz or so on top of the transmitted peak (it's really more of a band because of the fast feedback). These wiggles cause locking performance to suffer as well. This is difficult to untangle from the other issues. It appears laser feedback/current can be adjusted to suppress these wiggles. Then the transmitted power band looks smooth and the locked output is very stable.
*As per Nick the temp bandwidth is a couple degrees so we can adjust it by a 1/2 a degree or so to modify the shape of the error signal and get better locking performance. Considering the tuning sensitivity to temp (16deg/nm), we would want to adjust the temp a bit on opposite ends of a 1nm scan for example.
--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 17:51, 19 July 2014 (CDT)
Week in review: I've basically been working on 2 things, trying to get better lock performance and starting to write up the EIT eqns so we can look at that in the context of the green transition in Eu:YSO. Nick and I tried to look for absorption on thur but didn't see very good results; stability of the output power/lock issues are really fighting us. We did learn some things though:
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