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Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Christoph Affolderbach, Willam Moreno, A.E. Ivanov, T. Debogovic, Matthieu Pellaton, A.K. Skrivervik, E. De Rijk & Gaetano Mileti

Résumé Additive manufacturing (AM) of passive microwave components is of high interest for the cost-effective and rapid prototyping or manufacture of devices with complex geometries. Here, we present an experimental study on the properties of recently demonstrated microwave resonator cavities manufactured by AM, in view of their applications to high-performance compact atomic clocks. The microwave cavities employ a loop-gap geometry using six electrodes. The critical electrode structures were manufactured monolithically using two different approaches: Stereolithography (SLA) of a polymer followed by metal coating and Selective Laser Melting (SLM) of aluminum. The tested microwave cavities show the desired TE011-like resonant mode at the Rb clock frequency of ≈6.835 GHz, with a microwave magnetic field highly parallel to the quantization axis across the vapor cell. When operated in an atomic clock setup, the measured atomic Rabi oscillations are comparable to those observed for conventionally manufactured cavities and indicate a good uniformity of the field amplitude across the vapor cell. Employing a time-domain Ramsey scheme on one of the SLA cavities, high-contrast (34%) Ramsey fringes are observed for the Rb clock transition, along with a narrow (166 Hz linewidth) central fringe. The measured clock stability of 2.2 × 10−13 τ−1/2 up to the integration time of 30 s is comparable to the current state-of-the-art stabilities of compact vapor-cell clocks based on conventional microwave cavities and thus demonstrates the feasibility of the approach.
This work was supported by Space Positioning Measures of the Swiss Space Office of the State Secretariat for Education, Research and Innovation of the Swiss Confederation (SERI/SSO), call 2016. The authors also acknowledge support of the Swiss National Science Foundation, Grant Nos. 156621 and 162346, as well as previous support of the European Space Agency (ESA) and the European Metrology Research Programme (EMRP Project IND55-Mclocks). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. C.A., W.M., M.P., and G.M. thank C. E. Calosso (INRIM, Italy) for providing and support on the microwave local oscillator and F. Gruet and P. Scherler (both LTF, University of Neuchâtel, Switzerland) for support on the laser source and clock physics package.
   
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Citation C. Affolderbach, et al., "Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications," Applied Physics Letters, vol. 112, p. 1-5, Mar. 2018.
   
Type Article de périodique (Anglais)
Date de publication 16-3-2018
Nom du périodique Applied Physics Letters
Volume 112
Numéro 113502
Pages 1-5
URL https://doi.org/10.1063/1.5019444