## Sign of the refractive index in a gain medium with negative permittivity and permeability

JOSA B, Vol. 23, Issue 1, pp. 45-50 (2006)

http://dx.doi.org/10.1364/JOSAB.23.000045

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### Abstract

We show how the sign of the refractive index in any medium may be derived using a rigorous analysis based on Einstein causality. In particular, we consider left-handed materials, i.e., media that have negative permittivities and permeabilities at the frequency of interest. We find that the consideration of gain in such media can give rise to a positive refractive index.

© 2006 Optical Society of America

**OCIS Codes**

(000.2690) General : General physics

(350.7420) Other areas of optics : Waves

**ToC Category:**

Metamaterials

**Citation**

Yi-Fan Chen, Peer Fischer, and Frank W. Wise, "Sign of the refractive index in a gain medium with negative permittivity and permeability," J. Opt. Soc. Am. B **23**, 45-50 (2006)

http://www.opticsinfobase.org/josab/abstract.cfm?URI=josab-23-1-45

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### References

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