Nanoengineering of a Negative-Index Binary-Staircase Lens for the Optics Regime

TL;DR

This paper demonstrates the design, fabrication, and experimental validation of a binary-staircase lens with an effective negative index of refraction at 1.55 microns, enabling novel optical focusing capabilities.

Contribution

It introduces a method to engineer negative-index optical lenses using surface periodicity, expanding the optical properties available for future devices.

Findings

Successfully fabricated a negative-index binary-staircase lens in InP/InGaAsP.

Experimental focusing of plane waves confirmed the negative-index behavior.

Experimental results matched numerical simulations very well.

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 plano-concave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 microns 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.