Laser Locking for Long-term Magneto-Optical Trap Stability

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Laser Locking for Long-term Magneto-Optical Trap
Stability

• Kevin W. Vogel
• Advisor Georg Raithel

Presented 07/28/04
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Outline

• Magneto-Optical Trap (MOT)
• Laser Locking Methods
• Dichroic Atomic Vapor Laser Locking
• MOT Improvements

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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

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Diode Laser Frequency Stabilization

• Frequency changes due to temperature and
  diffraction grating position
• Tuned to transition frequency
• Locked with a feedback circuit

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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 ?

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DAVLL Setup
to MOT
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DAVLL Lock Signal

• Transition shifted by Zeeman effect

• Laser output is linearly polarized

• Each circular polarization is absorbed by a
  shifted transition

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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 0.003C

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Results
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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

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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