Extended slow-light field enhancement in positive/negative-index heterostructures

TL;DR

This paper introduces a novel bi-waveguide system combining positive and negative index materials, achieving extended electromagnetic enhancement through slow-light modes, with potential applications in strong light-matter interactions.

Contribution

The study presents the first demonstration of mesoscopic electromagnetic enhancement in a PIM/NIM heterostructure, supported by a theoretical model and numerical simulations.

Findings

Extended EM enhancement over wavelengths achieved

High coupling efficiency and modal bandwidth demonstrated

Unique energy velocity with opposite Poynting vector in the mode

Abstract

We present a bi-waveguide paradigm composed of joined Positive-Index-Material PIM)/Negative-Index-Material (NIM) slabs, demonstrating ultra-slow light propagation stemming from the competing propagation disposition in the PIM and NIM regions. We report for the first time a mesoscopic extended electromagnetic (EM) enhancement covering regions of the order of the free space wavelength, enabled by the slow-light mode in our system. Our dynamic numerical results are consistent with our developed theoretical model, predicting an EM energy accumulation reminiscent of a charging capacitor. Our analysis reveals that spatial compression is not a requirement to EM enhancement in slow-light systems and stresses on the merits of high coupling efficiency, strong temporal compression, monomodality and modal index bandwidth, -all present in our proposed paradigm. Furthermore, we show that the heterostructure waveguide mode is an extra-ordinary entity with a unique energy velocity, that is opposite to the Poynting vector in one of the participant waveguides. We believe these results will inspire new slow-light platforms relevant to the collective harvesting of strong light-matter interactions.