New miniaturized microwave cavity for Rubidium atomic clocks

Nowadays there is an increasing need for radically miniaturized and low-power atomic frequency standards, for use in mobile and battery-powered applications. For the miniaturization of double-resonance (DR) Rubidium (
⁸⁷
Rb) atomic clocks, the size reduction of the microwave cavity or resonator (MWR) to well below the wavelength of the atomic transition (6.835 GHz for
⁸⁷
Rb) has been a long-standing issue. Here we present a newly developed miniaturized MWR, the μ-LGR, consisting of a loop-gap resonator based cavity with very compact dimensions (volume <; 0.9 cm
³
). The μ-LGR meets the requirements of the atomic clock application and its assembly can be performed using repeatable and low-cost techniques. The concept of the proposed device was validated through simulations and prototypes were successfully manufactured and tested. High-quality DR spectra and first clock stabilities were demonstrated experimentally, proving that the μ-LGR is suitable for integration in a miniaturized atomic clock.