Microfabricated Atomic Clocks at NIST
NATIONAL INST OF STANDARDS AND TECHNOLOGY BOULDER CO TIME AND FREQUENCY DIV
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This paper presents the latest progress in the development, fabrication, and characterization of microfabricated atomic frequency references at NIST. With volumes below 10 mm3 the physics packages contain the complete integrated assembly for probing the ground-state hyperfine splitting frequency of the alkali atoms by coherent population trapping CPT. This technique allows for a simple and compact device containing a vertical-cavity surface-emitting laser VCSEL, optics to shape the laser beam, a vapor cell containing the atoms, and a detector. We present an improved technique for microfabricating the miniature alkali vapor cells. When integrated into a CPT clock, a clear reduction of long-term frequency drifts is observed. This leads to a fractional frequency instability of less than 10-11 at one hour of integration, a more than one order of magnitude improvement over previous results. We identify the remaining sensitivities of the clock frequency to environmental influences and propose ways to reduce them.
- Lasers and Masers
- Atomic and Molecular Physics and Spectroscopy