META 2021, META'12

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Negative Index of Refraction at Ultraviolet Frequencies
H. Lezec, T. Xu, M. Abashin, A. Agrawal, K. Chau

Last modified: 2012-02-04


In a left-handed medium (LHM), characterized by simultaneously-negative electric and magnetic polarization responses (Re[]<0 and Re[]<0), electromagnetic waves propagate with opposite directions of energy flow and phase velocity [1]. The ability of LHMs to sustain backwards waves leads to counter-intuitive phenomena such as negative phase refraction, where phase-fronts are refracted to the same side of the surface normal upon transmission of an electromagnetic plane wave incident from free space. In the ideal case of an isotropic LHM, the angles of the incident and transmitted wave-vectors obey Snell’s law, and the medium can be described by a constant, negative, index of refraction n. Since wave-vector and Poynting vector are strictly anti-parallel in an isotropic LHM, energy is refracted at the same angle. In particular, a low-loss, isotropic LHM with n=-1 could be used to build a far-field flat lens [1], with “superlens” potential for non-diffraction-limited imaging beyond the near-field region [2].