Dynamically Encircled Higher-order Exceptional Points in an Optical Fiber

TL;DR

This paper demonstrates the design and analysis of a specialized optical fiber with embedded higher-order exceptional points, enabling advanced control of light transmission through topological and dynamical encirclement techniques.

Contribution

It introduces a triple-core fiber with engineered gain and loss to realize and study third-order exceptional points and their topological light manipulation properties.

Findings

Successful realization of third-order EP in fiber

Observation of chiral and nonchiral light transmission behaviors

Potential for improved fiber-based light management devices

Abstract

The unique properties of exceptional point (EP) singularities, arising from non-Hermitian physics, have unlocked new possibilities for manipulating light-matter interactions. A tailored gain-loss variation, while encircling higher-order EPs dynamically, can significantly enhance the control of the topological flow of light in multi-level photonic systems. In particular, the integration of dynamically encircled higher-order EPs within fiber geometries holds remarkable promise for advancing specialty optical fiber applications, though a research gap remains in exploring and realizing such configurations. Here, we report a triple-core specialty optical fiber engineered with customized loss and gain to explore the topological characteristics of a third-order exceptional point (EP3), formed by two interconnected second-order exceptional points (EP2s). We elucidate chiral and nonchiral light transmission through the fiber, grounded in second- and third-order branch point behaviors and associated adiabatic and nonadiabatic modal characteristics, while considering various dynamical parametric loops to encircle the embedded EPs. We investigate the persistence of EP-induced light dynamics specifically in the parametric regions immediately adjacent to, though not encircling, the embedded EPs, potentially leading to improved device performance. Our findings offer significant implications for the design and implementation of novel light management technologies in all-fiber photonics and communications.