Achieving sub-diffraction imaging through bound surface states in negative-refracting photonic crystals at the near-infrared

TL;DR

This paper demonstrates sub-diffraction imaging in the near-infrared using negative-refracting photonic crystals, achieving high negative index figures-of-merit through bound surface states that enable evanescent wave refocusing.

Contribution

It reports the first experimental observation of near-field super-resolution imaging via bound surface states in negative index photonic crystals at near-infrared frequencies.

Findings

Effective negative index figure-of-merit of at least 380

Near-field resolution of 0.47 lambda, below diffraction limit

Resonant excitation of surface slab modes enables evanescent wave refocusing

Abstract

We report the observation of imaging beyond the diffraction limit due to bound surface states in negative refraction photonic crystals. We achieve an effective negative index figure-of-merit [-Re(n)/Im(n)] of at least 380, ~125x improvement over recent efforts in the near-infrared, with a 0.4 THz bandwidth. Supported by numerical and theoretical analyses, the observed near-field resolution is 0.47 lambda, clearly smaller than the diffraction limit of 0.61 lambda. Importantly, we show this sub-diffraction imaging is due to the resonant excitation of surface slab modes, allowing refocusing of non-propagating evanescent waves.