Improving electric field sensitivity by combining electromagnetically induced transparency, polarization spectroscopy, and microwave 3D printed lenses using hot vapor of Rydberg atoms as fundamental atomic sensors*

Rydberg atoms are ideal standard sensors for detecting electromagnetic (EM) fields because the outer electron is weakly bound to the core and is easily perturbed by stray EM fields. For high-definition eletrometry, the use of an atomic vapor sample contained in small glass or quartz cells appears promising. The amplitude of an a.c. electric field can be measured and quantified by analyzing the Autler-Townes energy splitting that appears in the EIT (Electromagnetic Induced Transparency) spectrum profiles; however, the contrast and sensitivity are limited by the measured field intensity, as for small fields the splitting is no longer available directly due to the transparency linewidth and power broadening limitations. To achieve a better definition, a combination of PS (Polarization Spectroscopy) and a Laguerre-Gaussian modified control beam can be used [1]. In this work, we go a step further in applying PS to the EIT scheme in order to obtain systematic measurements of microwave fields in the range of tens of gigahertz. By manipulating the polarization of the control and probe lasers a dispersion signal is generated, and an indirect splitting can be quantified for even lower electric fields. The increased detection sensitivity can be improved by using 3D-printed dieletric lenses; this passive element can be manufactured using metasurfaces to control the wavefront phases, leading to an increase in gain at the sensor reading position [2].  

[1] Duarte Gomes, N.; da Fonseca Magnani, B.; Massayuki Kondo, J.D.; Marcassa, L.G. Polarization Spectroscopy Applied to Electromagnetically Induced Transparency in Hot Rydberg Atoms Using a Laguerre–Gaussian Beam. Atoms 2022, 10, 58. https://doi.org/10.3390/atoms10020058

[2] V. M. Pepino, A. F. da Mota, A. Martins and B. -H. V. Borges, "3-D-Printed Dielectric Metasurfaces for Antenna Gain Improvement in the Ka-Band," in IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 11, pp. 2133-2136, Nov. 2018, doi: 10.1109/LAWP.2018.2860521.