Cavity-enhanced polarization rotation measurements for low-disturbance probing of atoms

Abstract

We propose and demonstrate cavity-enhanced polarization-rotation measurement as a means to detect magnetic effects in transparent media with greater sensitivity at equal optical disturbance to the medium. Using the Jones calculus, we compute the effective polarization rotation effect in a Fabry-Perot cavity containing a magnetic medium, including losses due to enclosure windows or other sources. The results show that when measuring polarization rotation, collecting the transmitted light has advantages in simplicity and linearity relative to collecting the reflected light. We demonstrate the technique by measuring Faraday rotation in a 87Rb atomic ensemble in the single-pass and cavity-enhanced geometries, and observe enhancement in good agreement with the theoretical predictions. We also demonstrate shot-noise-limited operation of the enhanced rotation scheme in the small-angle regime.

Laser-written vapor cells for chip-scale atomic sensing and spectroscopy

“…However, due to the planar bonding or lithographic strategy, all these cells do not show 3D versatility and have limited optical access. Many atomic sensors like those based on multipass cells [34][35][36], cell arrays [37], dual-beam [38], triple-beam [39,40] or cavity-enhanced [41,42] geometries, do require greater flexibility and optical access. Various strategies have been also developed for the integration of vapor cells with photonic waveguides.…”