Jared lab notebook

--Jmiles2 (talk) 12:39, 13 May 2014 (CDT)

I need close to 17 mW of seed power for the 2nd FORT beam to work at 2 Watts. Although this is is in the range of acceptable powers for this TA I still want to contact M2K lasers and make sure the Intensity is not too high. I can only get about 40% through the AOM when powering it with 2 Watts. I get around 33% out of the fiber at higher power (~600 mW). I get over 200 mW from the output of the fiber.
Need two AWG outputs for evaporative cooling of both FORT lasers. For the FPGA, FORT on/of Channel 14, is a switch to the FORT 1 amplifier, and turns it on or off. The RF in to the amplifier is controlled by the AWG which is triggered from CHannel 10, FORT AWG. OFF means the AWG is triggered.

--Jmiles2 (talk) 14:25, 14 May 2014 (CDT) For the AWG/hittite chip on FORT 1, 3db input on CW setting is equivalent to 33 to 33.2 dbm output power, 2 Watts, maybe a tad more. Since I'm not running this all the time, I think slightly more than 2 Watts should be fine. On pulse setting, 0 V input gives 11.5 dbm and -700 mV gives 32.8 dbm. A little over 20 dbm attenuation, that should work fine for what we're doing. The majority of attenuation happens from 0 to -200 mV.

I made an identical circuit for FORT 2. at 0 V, the output is 33 dbm for 4.5 dbm input power. The input power might change based on what RF generator you use, always check it first. At 700 mV the output is 4 dbm, 29 dbm range, I think the circuit for regulating the current to the chip is slightly off in the FORT 1 circuit. 4 dbm input give 33 dbm at CW setting.

--Jmiles2 (talk) 11:05, 15 May 2014 (CDT) Need to get FORT 1 laser to one polarization. Alignment affects polarization, looks like most of the light is vertically polarized. 19 amps give me 20 Watts in vertical direction. ~20 Watts is max for the AOM. Put in a wave plate to change to horizontally polarized so it would go through the beam cube. Still get good efficiency through beam cube, 45% to 50% at high powers. I get a little over 7 Watts after the beam cube.

FORT 2 is now aligned to the MOT. I can get atoms trapped with either FORT now, they are aligned over top of one another and I can load FORT 2 from the atoms in FORT 1, with no MOT. Need to check lifetimes of both.

--Jmiles2 (talk) 16:14, 19 May 2014 (CDT) Lifetime of FORT 1 is now much longer than it used to be. I'm not sure why, but it might be because the laser power is not jumping around as much. It was moving around by as 20% on the photo diode when evaporative cooling at the end of March. The only thing that is different is that I have the laser going through a beam cube, and have optimized the alingment so that the Horizontal linearly polarized light is maximized at ~18 Amps of laser current. 18 to 19 amps should be operating current, around 20 Watts on the AOM.
Taking different temperature measurements for different evaporation times, up to ~400ms.

--Jmiles2 (talk) 10:09, 21 May 2014 (CDT) Lifetime data from Both FORTS. Lifetime Data Fort Lifetimes. Green is the high power FORT around March 2014 and Black is the same FORT in May 2014. Red is the TA FORT, also taken in May 2014.