Circularly Polarized Directional Resonator for Rydberg Atomic Enhancement Sensing

In this study, we propose a circularly polarized directional resonator (CPDR) to enhance the reception capability of circularly polarized (CP) waves by the Rydberg atomic sensor and suppress unwanted directional waves to improve interference resistance. By utilizing the ac Stark effect, the CPDR provides a 14.1 dB enhancement for left-hand CP electric fields at 2.388 GHz. In the atomic heterodyne scenario, the CPDR enables a sensing sensitivity of 148.8 μV/cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sqrt {\text{Hz}} $</tex-math></inline-formula>, with an axial ratio reduced to 2.4 dB. Furthermore, we experimentally investigated the reception pattern of the CPDR, which aligns with the results of the characteristic-mode simulation. The measured pattern indicates that the proposed CPDR exhibits excellent directional reception performance with a 3 dB beamwidth of 39°. This CPDR expands the range of enhancement resonators for Rydberg atomic sensing and shows significant potential, particularly for satellite signal reception.