laser locking for long-term magneto-optical trap stability kevin w. vogel advisor: georg raithel...
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Laser Locking for Long-term Magneto-Optical Trap
Stability
Kevin W. Vogel
Advisor: Georg Raithel
Presented 07/28/04
Outline
• Magneto-Optical Trap (MOT)• Laser Locking Methods• Dichroic Atomic Vapor Laser
Locking• MOT Improvements
Magneto-Optical Trap (MOT)
• Capture and cool Rubidium atoms to μK temps
• 6 orthogonal pairs of circularly polarized counter propagating laser beams
• Anti-Helmholtz magnetic field
Diode Laser Frequency Stabilization
• Frequency changes due to temperature and diffraction grating position
• Tuned to transition frequency• Locked with a feedback circuit
Frequency ν
0 Volts
Laser Locking Methods• Saturated Absorption
Spectroscopy– Narrow locked frequency
range– Easy to lose lock– Lock time: 10 – 60 min.
• Dichroic Atomic Vapor Laser Locking (DAVLL)– Difficult to lose lock– Broader locked frequency
range– Lock time: ?
5 MHz
0 V
0 V
500 MHz
DAVLL Setup
to MOT
DAVLL Lock Signal
• Laser output is linearly polarized
• Transition shifted by Zeeman effect
• Each circular polarization is absorbed by a shifted transition
Improvements:
• Low Noise Circuit– Produces differential absorption signal
with minimal electrical noise
• Temp Controlled Permanent Magnets– Permanent magnet field strength is
temperature dependent– Keeps temp within ±0.003°C
Results43200s (07/20/04 6pm-7am)
-1-0.50
0.51
1.52
2.53
0 5000 10000 15000 20000 25000 30000 35000 40000
Time (s)
MO
T A
tom
s (1
0^5)
36000s (07/13/04 9pm - 7am)
-1-0.50
0.51
1.52
2.53
0 5000 10000 15000 20000 25000 30000 35000 40000
Time (s)
MO
T A
tom
s (1
0^5)
mode hops
14 hours!
Other MOT Improvements
• Permanent heater to clean Rubidium cell
• Larger vacuum chamber cell to increase atom flow
• Magnetic coils for larger cell• New laser grating and bracket
Acknowledgments
• Georg Raithel, Ramon Torres-Isea, Spencer Olson, Rahul Mhaskar, Tara Cubel, Aaron Reinhard, Natalya Morrow, Rui Zhang, Brenton Knuffman, Alisa Walz-Flannigan, Jae-Hoon Choi, Eberhard Hansis, Alex Povilus
• NSF• Physics Department
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