Exceptional-point-induced asymmetric mode conversion in a dual-core optical fiber segment.

The engineering of exceptional points (EPs) in open optical systems has lately attracted much attention for developing future all-optical devices. However, investigation of the fascinating features of EPs in fiber geometries is lacking. We design a fabrication feasible dual-core optical fiber segment, where non-Hermiticity in terms of a symmetric customized gain-loss profile is introduced to modulate the interaction between two corresponding coupled modes toward hosting a dynamical EP encirclement scheme in the gain-loss parameter space.

Chirality breakdown in the presence of multiple exceptional points and specific mode excitation.

The dynamical parametric encirclement around a second-order exceptional point (EP) enables the time-asymmetric nonadiabatic evolution of light, which follows the chirality of the underlying system. Such light dynamics in the presence of multiple EPs and the corresponding chiral aspect is yet to be explored. In this Letter, we report a gain-loss assisted four-mode-supported optical waveguide that hosts a parameter space to dynamically encircle multiple EPs.