A giant electro-optic effect using polarizable dark states

• Published in: Nature physics Vol. 4; no. 11; pp. 890 - 894
• Main Authors: Mohapatra, Ashok K, Adams, Charles S, Bason, Mark G, Butscher, Björn, Weatherill, Kevin J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2008; Nature Publishing Group
• Subjects: Atomic; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Electric fields; Mathematical and Computational Physics; Molecular; Nonlinear systems; Optical and Plasma Physics; Optics; Physics; Physics and Astronomy; Theoretical
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys1091

The electro-optic effect, where the refractive index of a medium is modified by an electric field, is of central importance in nonlinear optics, laser technology, quantum optics and optical communications. In general, electro-optic coefficients are very weak and a medium with a giant electro-optic coefficient could have profound implications for precision electrometry and nonlinear optics at the single-photon level. Here we propose and demonstrate a giant d.c. electro-optic effect on the basis of polarizable (Rydberg) dark states. When a medium is prepared in a dark state consisting of a superposition of ground and Rydberg energy levels, it becomes transparent and acquires a refractive index that is dependent on the energy of the highly polarizable Rydberg state. We demonstrate phase modulation of the light field in the Rydberg-dark-state medium and measure an electro-optic coefficient that is more than six orders of magnitude larger than in usual Kerr media. Coupling of the Rydberg states of an ensemble of rubidium atoms gives rise to a d.c. Kerr effect that is six orders of magnitude greater than in conventional Kerr media. Such phenomena could enable the development of high-precision electric field sensors and other nonlinear optical devices.