Microwave-field sensing via electromagnetically induced absorption of Rb irradiated by three-color infrared lasers

A microwave electric field sensing has been set up based on a three-color electromagnetically induced absorption in rubidium vapor cell via cascading transitions. All transitions are irradiated by infrared lasers: a 780 nm laser servers as probe to monitor the optical transmittancy via transition 5S(1/2)-> P-3/2;, a 776 rnm laser and a 1260 nm laser are used to couple the states 5P(3/2) and 5D(5/2) and states 5D(5/2) and 44F(7/2), respectively. We find that a frequency detuning similar to 2 pi x (- 40) MHz of the 776 rim dressing beam prefers to a better signal-to-noise ratio for the probe beam. The off-resonance greatly depresses the double resonance pumping effect. A demonstration measurement for the electric field of microwave 1.18988 GHz, corresponding to the coupling resonance between two adjacent Rydberg states 44F(7/2) and 44F(9/2), gives a sensitivity of 55.79(23) nVcm(-1)/root Hz and a smallest discernible electric field of 78.9(33) nVcm(-1) in time scale of 500 ms. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement