Microwave-field sensing via electromagnetically induced absorption of Rb irradiated by three-color infrared lasers
Shuhang You, M. H. Cai, S. S. Zhang, Z. S. Xu, Hongping Liu
Abstract
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 nm 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 ∼2 π × ( − 40) MHz of the 776 nm 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>55.79</mml:mn> <mml:mo stretchy="false">(</mml:mo> <mml:mn>23</mml:mn> <mml:mo stretchy="false">)</mml:mo> <mml:mspace width="thickmathspace"/> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mtext>nVcm</mml:mtext> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:msqrt> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mtext>Hz</mml:mtext> </mml:mrow> </mml:msqrt> </mml:math> and a smallest discernible electric field of 78.9(33) nVcm −1 in time scale of 500 ms.