Non-orthogonal cavity modes near exceptional points in the far field

Abstract

Non-orthogonal eigenstates are a fundamental feature of non-Hermitian systems and are accompanied by the emergence of nontrivial features. However, the platforms to explore non-Hermitian mode couplings mainly measure near-field effects, and the far-field behaviour remain mostly unexplored. Here, we study how a microcavity with non-Hermitian mode coupling exhibits eigenstate non-orthogonality by investigating the spatial field and the far-field polarization of cavity modes. The non-Hermiticity arises from asymmetric backscattering, which is controlled by integrating two scatterers of different size and location into a microdisk. We observe that the spatial field overlaps of two modes increases abruptly to its maximum value, whilst different far-field elliptical polarizations of two modes coalesce when approaching an exceptional point. We demonstrate such features experimentally by measuring the far-field polarization from the fabricated microdisks. Our work reveals the non-orthogonality in the far-field degree of freedom, and the integrability of the microdisks paves a way to integrate more non-Hermitian optical properties into nanophotonic systems.

11pages, 4 figures

References in corpus (11)

• Efficient Light Funneling based on the non-Hermitian Skin Effect
• Dynamically encircling exceptional points: Exact evolution and polarization state conversion
• Exceptional Points in Atomic Spectra
• Chiral Coherent Perfect Absorption on Exceptional Surfaces
• Dynamically manipulating topological physics and edge modes in a single degenerate optical cavity
• Enhanced Strong Interaction between Nanocavities and p-shell Excitons Beyond the Dipole Approximation
• Diabolical Points in Coupled Active Cavities with Quantum Emitters
• Quantum state discrimination in a PT-symmetric system
• Enhanced emission from a single quantum dot in a microdisk at a deterministic diabolical point
• Anomalous spontaneous emission dynamics at chiral exceptional points
• Imperfect chirality at exceptional points in optical whispering-gallery microcavities

Cited by in corpus (3)

• Full Polarization Control of Photons with Evanescent Wave Coupling in the Ultra Subwavelength Gap of Photonic Molecules
• Topological Operations Around Exceptional Points via Shortcuts to Adiabaticity
• Local perfect chirality at reflection-zeros away from exceptional points in optical whispering gallery microcavity