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Micro atomic clock

Chip-scale atomic clocks are in great demand for navigation purposes. Typically, in such clocks a local oscillator , “a flywheel”, is locked to a natural frequency reference, such as e.g. hyperfine ground state splitting in alkali atoms. This splitting may be accessed via Raman spectroscopy and typically measures several GHz. The signal source at such frequency is by far the bulkiest and most power-hungry part of the atomic clock. Our approach is to eliminate this part altogether, implementing a self-oscillating opto-electronic loop where electro-magnetically induced transparency in Rubidium atoms serves as a photonic filter. This filter forces our system to oscillate at exactly half of the hyperfine splitting frequency of 6.8 GHz.

The table-top prototype version of our self-oscillating atomic clock is shown in Figure 1 and is performance is given in Figure 2, blue and red for different feedback mechanisms (blue for an EOM and a frequency-locked laser, red for directly-injected free-running VCSEL).

micro atomic clock

Figure 1: The table-top prototype version of our self-oscillating atomic clock

allan deviation graph

Figure 2: Performance of above table-top version shown in Figure 1

Remarkably, selecting a different atomic transition with the same experimental setup, we realize a self-oscillating magnetometer [2]. This magnetometer combines a high bandwidth and large dynamic range with good accuracy, and has advantages over many state of the art magnetometers, see Figures 3 and 4.

dynamic range chart

Figure 3: Dynamic range

response bandwidth chart

Figure 4: Response bandwidth

Working with Sandia in the DARPA Integrated Micro Primary Atomic Clock Technology (IMPACT), we are helping  develop a micro trapped ion atomic clock.

 

Publications

  1.   Dmitry Strekalov, David Aveline, Nan Yu, Robert Thompson, Andrey B. Matsko and Lute Maleki, “Stabilizing an optoelectronic microwave oscillator with photonic filters,”J. of Lightwave Technology, 21, 3052-61 (2003) 93, 24395 (2004).
  2. Lute Maleki, Dmitry Strekalov and Andrey B. Matsko, “Magnetometer based on the opto-electronic microwave oscillator,”Opt. Com. 247, 141-148 (2005).