Polarization-rotation resonances with subnatural widths using a control laser

Abstract

We demonstrate extremely narrow resonances for polarization rotation in an atomic vapor. The resonances are created using a strong control laser on the same transition, which polarizes the atoms due to optical pumping among the magnetic sublevels. As the power in the control laser is increased, successively higher-order nested polarization rotation resonances are created, with progressively narrower linewidths. We study these resonances in the $D_2$ line of Rb in a room-temperature vapor cell, and demonstrate a width of $0.14\Gamma$ for the third-order rotation. The explanation based on a simplified $\Lambda$V-type level structure is borne out by a density-matrix analysis of the system. The dispersive lineshape and subnatural width of the resonance lends itself naturally to applications such as laser locking to atomic transitions and precision measurements.

5 pages, 6 figures

References in corpus (3)

• Narrow absorptive resonances in a four-level atomic system
• Electromagnetically Induced Transparency versus Nonlinear Faraday Effect. Coherent Control of the Light Beam Polarization
• Role of different type of sub-systems in doubly driven Lambda-system in 87Rb