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--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 00:32, 26 July 2014 (CDT)
What did we learn today? Well today was a pretty prime example of why i was a bit anxious about building up stuff this late in my grad school run. I spent the day trying to get the 1055 seed laser diode to cooperate. It's capable of doing what we want but has been difficult, i did learn/re-learn a few things:
* Tried different polarization orientations. We want the spatial elliptical spot to be horizontal, but changing the angle changes how well the light is reflected from the grating and and as a result, how well the optical feedback works. I could observe different orientations having different amounts of feedback (or absence of feedback) but it was not an obvious relation- probably in part because the method to turn the tube is kind of crude.
* Tried changing the cavity length. This didn't seem to do too much.
* Tried adjusting the collimation. This ended up being the most important adjustment. Initially i adjusted the collimation just down the table, but this was too short a distance to look. Then Jared helped me collimate it on the wall and the feedback performance upon tune-up was much better. Saw threshold test go from 200uW to 1.6mW, pretty dramatic. My suspicion is that if the output is better collimated, the feedback light reflected back through the lens focuses much better. If it focuses better, you get better feedback and more single-mode behavior. When it was tuned up, we were able to scan over several GHz just by adjusting the seed diode laser piezo. The SHG cavity even stayed locked while changing the wavelength.
* Immediately after tuning everything up, the laser was much better behaved, we were able to scan over the abs feature without the laser messing up during hte scam.
--[[User:Zjsimmons|Zjsimmons]] ([[User talk:Zjsimmons|talk]]) 10:52, 24 July 2014 (CDT)
Re: 1055nm Laser:
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