A giant electro-optic effect using polarizable dark states


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.

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Figure 1: Principle of the giant electro-optic effect using polarizable dark states.
Figure 2: Effect of an external electric field on the transmission through the polarizable dark-state medium.
Figure 3: Measurement of the Kerr constant, B0.
Figure 4: Power spectrum of the signal light transmitted through the dark-state ensemble.


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We are grateful to E. Riis, T. Pfau, M. P. A. Jones, S. L. Cornish and I. G. Hughes for stimulating discussions, R. P. Abel for technical assistance and S. L. Cornish for loan of equipment. We thank the EPSRC for financial support.

Author information

A.K.M. and C.S.A. contributed to project planning and data analysis, M.G.B., B.B., K.J.W. and A.K.M. contributed to experimental work, M.G.B., A.K.M. and C.S.A. contributed to theoretical modelling and all authors contributed to writing and editing the manuscript.

Correspondence to Ashok K. Mohapatra or Charles S. Adams.

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Mohapatra, A., Bason, M., Butscher, B. et al. A giant electro-optic effect using polarizable dark states. Nature Phys 4, 890–894 (2008). https://doi.org/10.1038/nphys1091

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