Local Oscillator Port-Integrated Resonators for Sensitivity Enhancement of VHF Band Rydberg Atomic Heterodyne Receivers

The Rydberg atomic heterodyne technique and resonant structures represent two prominent approaches that can notably enhance the sensing sensitivity of Rydberg atomic receivers in the atomic and microwave domains, respectively. However, current implementations exhibit low levels of integration, particularly in the VHF band. This article introduces local oscillator (LO) port-integrated resonators (LOIRs) to synergize these methods, aiming to improve sensitivity and system integration in Rydberg atom-based receivers. Through an analysis of the electric field distribution in the split-ring resonator (SRR), we developed two types of LOIRs: the standing wave type LOIR (SIR) and the traveling wave type LOIR (TIR). Experimental investigations were conducted at 264 MHz using a vapor cell containing cesium atoms in the resonators. Spectral measurements indicate that the SIR and TIR provide enhancement factors of 45.8 and 45.3 dB, respectively. When employing the SIR and TIR for Rydberg atomic heterodyning, sensitivity significantly improved to 104.34 and 105.54 (nV/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>, respectively. Furthermore, in comparison to the SRR setup in the atomic heterodyne scenario, the LO power consumption decreased to 22.4% and 3.7% with the SIR and TIR, respectively. This research represents a significant advancement toward the practical application of Rydberg atomic receivers.