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Jared lab notebook: Difference between revisions
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--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 15:54, 3 December 2014 (CST)
Checked the Beam size of the Coupling beams, I thought they hadn't changed since the last time, but ChB was ~2 mm diameter 1/e^2 and ChC was ~1.7 mm diameter 1/e^2. Probe was still about 2.6 mm. Bigger than the coupling beam but it makes alignment much easier, and there is plenty of power to use for the Probe.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 15:21, 9 January 2015 (CST)
We are trying the experiment with different m levels. Part of the hyperfine repumper is used as a pump to get most of the atoms into the m=0 F=1 level. This way we can more easily model what will happen with the EIT pulses.
I'm also trying the experiment with higher intensity lasers. My model shows less oscillations in the populations of the three levels over time, and therefore the system reaches a steady state faster
Some data taken today shows that there is a difference with EIT between the two coupling beams. I want took transfer data from 1 of the coupling beams. Then I put the beam into the other fiber launch, so it's propagating in the opposite direction. The two transfer curves did not look the same, but I didn't check the beam sizes. I want to try this again more thoroughly because this could be a big deal... I don't know why they would be different though.
I check to see if either beam was clipping the chamber, and it seems that both are missing the chamber and a large amount of the power is going out the otherside.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 15:49, 11 January 2015 (CST)
I think something is wrong with the beam coming from ChB. I can move the ChC beam to the ChB fiber launch and get very similar data. I took some data on Jan 9 about this. I should look at the fiber output and make sure it's anice gaussian mode. I might switch fibers and redo timings too. The output looks fine on the camera, but it's still something to try. The ChB beam was not transferring as many atoms with EIT as the ChC beam was. the powers were the same and the fact the ChC beam did similar transfers and similar powers from each fiber launch means the beam sizes are correct.
I checked the timings of the ChB beam and it looked really good.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 15:44, 12 January 2015 (CST)
Light from the ChB AOM set up transfers less atoms the the ChC set up. It's something with the AOM timings or something with the fiber.
I'm convinced that CHC transfers better, but I'm not sure why. I'm going to move the circuit that pumps everything to F=1 to the CHB AOM to see if that circuit is messing things up.
After I did this both seemed to working fine. Not sure what was happening but I did notice that the lock on the diode for the EIT lasers was not that great. It would move around a little when locked. To fix it I turned down the sensitivity of the lock in amplifier.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 21:23, 28 January 2015 (CST)
Today I took some scans from 0 to 4 mW and 0 to 2 mW. A coulple of days ago I took very good data on the EIT transfer of both beams with each of there pulses. The figure has all 4 plots on it, and are very similar. I'm not getting good narrow data though. Not really sure why, I get coupling from ChB control beam into ChC fiber. I used thorlabs differential screws to better align the CHC coupling beam and the probe to the fort atoms.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 17:17, 5 February 2015 (CST)
I get a standing wave with more than 10% contrast when I optically pump to m=0. I also narrowing when I went from 2 mW to 50 mW, but not from 2 to 30. The simulations say both of these regions should get a narrow feature, but the simulation has not been matching the experiment very well. I was trying to get the optical pumping even better, but I think I will take a long scan of this narrow data, with the majority of the atoms starting in m=0, this would be a new data set.
Then I'm going to make the pulses rise times longer by changing their size through the AOM's. This should put us more in the dark state and eliminate the oscillations we see in the simulatinos for the transfer data.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 17:00, 24 February 2015 (CST)
Changed the pulse times by using a longer focal length, approximately twice the focal length of the original lenses. the rise times are closer to 50 ns, rather than 25 ns.
The FORT power decreased the other, tried to fix it but couldn't get the same amount of power out, maybe something is wrong with this Chinese laser. Got the FORT back though with similar atom number, now trying to get optical pumping to work better. I get EIT, but I'd like to do EIT closer on resonance.
Need to do standing wave closer to resonance to ensure that we're better in the dark state. This will match simulations better.
I checked the beam sizes, The probe is 1650X1500um +- 50 um Both coupling beams are about 1600X 1600 +- 50 um.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 16:10, 31 March 2015 (CDT)
I keep seeing some asymmetric stuff with the standing wave depending on which way I move the standing wave. We're moving the probe beam to be perpendicular to the coupling beams. We'll need to change the polarizations to so they are perpendicular to each other and the B field which defines our z axis.
We used to use vertically polarized coupling beams and horizontally polarized probe beam, now we'll be using vertically probe and horizonatll coupling.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 13:39, 24 April 2015 (CDT)
I've been trying to get narrower data, but no luck. I checked the beam sizes and they were all around 1700x1700 um. easily + or - 50 um though. I will got through the data I have and put some of it together to try and put together the paper.
I used 10 Amps on the coils for optical pumping, and I have proof that this does pump atoms into the m=0 level.
--[[User:Jmiles2|Jmiles2]] ([[User talk:Jmiles2|talk]]) 14:49, 3 May 2015 (CDT)
I'm trying to make some figures in Matlab for the paper, if you go into more properties when having the figure open with "plot tools" you can manually set the size of the figure through PlotBoxAspectRatio. Useful for getting all graphs to be the same for the paper.
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