Nanoengineering of a negative-index binary-staircase lens for the optics regime

B. D. F. Casse, Northeastern University
R. K. Banyal, Northeastern University
W. T. Lu, Northeastern University
Y. J. Huang, Northeastern University
S. Selvarasah, Northeastern University
Mehmet R. Dokmeci, Northeastern University
S. Sridhar, Northeastern University

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Originally published in Applied Physics Letters, v.92 no.24 (2008).  doi:10.1063/1.2942383

Abstract

We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.