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 (⁸⁷Rb) 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 ⁸⁷Rb) has been a long-standing issue. <br> Here we present a newly developed miniaturized MWR, the <i>μ</i>-LGR, consisting of a loop-gap resonator based cavity with very compact dimensions (volume < 0.9 cm³). The <i>μ</i>-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. Highquality DR spectra and first clock stabilities were demonstrated experimentally, proving that the <i>μ</i>-LGR is suitable for integration in a miniaturized atomic clock.