Light confinement by local index tailoring in inhomogeneous dielectrics

TL;DR

This paper introduces a theoretical method to locally tailor the refractive index in inhomogeneous 1D dielectrics, enabling precise control of light intensity profiles without affecting external measurements, advancing light confinement techniques.

Contribution

The authors develop a novel approach for local index tailoring in inhomogeneous media, allowing independent control of internal light fields without altering external optical properties.

Findings

Achieved local control of light intensity inside 1D inhomogeneous media.

Extended the method to multilayer films and coupled micro-resonator chains.

Demonstrated undetectable local modifications to external optical measurements.

Abstract

The engineering of light confinement is a topic with a long history in optics and with significant implications for the control of light-matter interaction. In inhomogeneous and disordered media, however, multiple scattering prevents the application of conventional approaches for the design of light fields with desired properties. This is because any local change to such a medium typically affects these fields in a non-local and complicated fashion. Here, we present a theoretical methodology for tailoring an inhomogeneous one-dimensional (1D) Hermitian dielectric index distribution, such that the intensity profile of an incoming light field can be controlled purely locally, i.e., with little or no influence on the field profile outside of a designated region of interest. Strongly increasing or decreasing the light's intensity at arbitrary positions inside the medium thereby becomes possible without, in fact, changing the external reflectance or transmittance of the medium. These local modifications of the medium can thus be made undetectable to unidirectional far field measurements. We apply our approach to locally control the confinement of light inside 1D materials with inhomogeneous continuous refractive index profiles and extend it to multilayer films as well as to chains of coupled micro-resonators.