Rethinking photonic nanojets: a new definition and design paradigm

TL;DR

This paper redefines photonic nanojets with a rigorous framework, introduces a new quality metric based on optimal mass transport, and proposes a phase-only modulation method for steering PNJs without mechanical adjustments.

Contribution

It provides a new, physically interpretable definition of PNJs, a quantifiable quality metric, and a novel steering technique using phase modulation.

Findings

Resolved ambiguities in PNJ measurement

Introduced an optimal mass transport-based quality metric

Demonstrated phase-only steering of PNJs

Abstract

We propose a rigorous, physically interpretable, and quantifiable definition of the photonic nanojet (PNJ). This framework resolves longstanding ambiguities in measuring PNJ dimensions and leverages an optimal mass transport-based metric to quantify PNJ quality. Building on this metric, we develop a PNJ steering methodology that requires no opto-mechanical intervention, relying solely on phase-only illumination modulation.