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Two-frequency acousto-optic modulator driver to improve the beam pointing stability during intensity ramps
B Fröhlich1, T Lahaye, B Kaltenhäuser
15. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart, Germany.
The Review of Scientific Instruments
|May 5, 2007
Summary
We developed a method to stabilize laser beams from acousto-optic modulators (AOMs). By using two radio frequencies, we reduced beam pointing instability by 20x, crucial for ultracold atom experiments.
Area of Science:
- Atomic, Molecular & Optical Physics
- Experimental Physics
- Laser Physics
Background:
- Acousto-optic modulators (AOMs) are used in experiments with ultracold atoms.
- Thermal effects in AOMs cause beam pointing instability when intensity is modulated.
- This instability can be up to 1 mrad, impacting precision experiments.
Purpose of the Study:
- To improve the pointing stability of the first-order diffracted beam from an AOM.
- To mitigate beam displacement caused by radio-frequency power changes in AOMs.
- To provide a simple solution for ultracold atom experiments.
Main Methods:
- Driving the AOM with two radio frequencies, f(1) and f(2).
- Adjusting the power of f(2) relative to f(1) to maintain constant total power.
- Implementing the method without optical modifications to existing setups.
Main Results:
- Beam displacement due to thermal effects was decreased by a factor of 20.
- The pointing stability of the first-order diffracted beam was significantly enhanced.
- The method proved effective in stabilizing beams for experiments like forced evaporative cooling.
Conclusions:
- A simple and effective scheme was demonstrated to improve AOM beam pointing stability.
- The dual-frequency driving method offers a practical solution for precision experiments.
- This technique is readily applicable to existing experimental apparatus.
