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Waveguides are fundamental components in communication systems. However, they suffer from reflection and scattering losses at sharp routes or defects. The breakthrough in developing topological photonic crystals (PhCs) provides promising…

Applied Physics · Physics 2024-01-03 Rui Zhou , Minglin L. N. Chen , Xingtong Shi , Yan Ren , Zihao Yu , Yu Tian , Y. Liu , Hai Lin

We demonstrate that exceptional points of degeneracy (EPDs) are obtained in two coupled waveguides without resorting to gain and loss. We show the general concept that modes resulting from a proper coupling of forward and backward waves…

Optics · Physics 2023-02-01 Tarek Mealy , Filippo Capolino

The growing complexity of integrated photonics necessitates compact, low-power devices that transcend traditional, material-centric design approaches. In this study, we harness non-Hermitian physics to uncover novel properties of coupled…

Optics · Physics 2025-10-30 P. Chang , S. Ramezanpour , A. Helmy

We demonstrate that modulations of the stiffness properties of an elastic plate along a spatial dimension induce edge states spanning non-trivial gaps characterized by integer valued Chern numbers. We also show that topological pumping is…

Mesoscale and Nanoscale Physics · Physics 2020-04-01 Emanuele Riva , Matheus I. N. Rosa , Massimo Ruzzene

In this work, we propose a completely general method to pump the gapped topological modes of a lattice of optical waveguides by controlling the propagation constant of an auxiliary waveguide and its coupling to the main lattice. In this…

Optics · Physics 2023-02-13 David Viedma , Jordi Mompart , Verònica Ahufinger

Driven-dissipative systems provide a natural setting for the emergence of exceptional points -- i.e. non-Hermitian degeneracies where eigenmodes coalesce. These points are important for applications such as sensing, where enhanced…

Materials Science · Physics 2025-10-21 Mawgan A. Smith , Ryan D. McKenzie , Alban Joseph , Robert L. Stamps , Rair Macêdo

Resonance coupling in non-Hermitian systems can lead to exotic features, such as bound states in the continuum (BICs) and exceptional points (EPs), which have been widely employed to control the propagation and scattering of light. Yet,…

Optics · Physics 2022-04-01 Zi-Lan Deng , Feng-Jun Li , Huanan Li , Xiangping Li , Andrea Alù

Topological photonics has recently emerged as a route to realize robust optical circuitry, and nonlinear effects are expected to enable tunability of topological states with the light intensity. Here we realize experimentally nonlinear…

We introduce non-Hermitian plasmonic waveguide-cavity systems with topological edge states (TESs) at singular points. The compound unit cells of the structures consist of metal-dielectric-metal (MDM) stub resonators side-coupled to an MDM…

Optics · Physics 2021-10-12 Yin Huang , Yuecheng Shen , Georgios Veronis

Physical systems with loss or gain feature resonant modes that are decaying or growing exponentially with time. Whenever two such modes coalesce both in their resonant frequency and their rate of decay or growth, a so-called "exceptional…

We present a full study of an improved nonlinear plasmonic slot waveguides (NPSWs) in which buffer linear dielectric layers are added between the Kerr type nonlinear dielectric core and the two semi-infinite metal regions. For TM polarized…

Guided modes of an open periodic waveguide, with a periodicity in the main propagation direction, are Bloch modes confined around the waveguide core with no radiation loss in the transverse directions. Some guided modes can have a complex…

Optics · Physics 2020-10-28 Amgad Abdrabou , Ya Yan Lu

One-dimensional superlattices with modulated coupling constants show rich topological properties and tunable edge states. Beyond the dimeric case, probing the topological properties of superlattices is a challenge. Here we suggest a rather…

Optics · Physics 2020-12-15 Stefano Longhi

We consider a planar waveguide with combined Dirichlet and Neumann conditions imposed in a "twisted" way. We study the discrete spectrum and describe it dependence on the configuration of the boundary conditions. In particular, we show that…

Spectral Theory · Mathematics 2015-05-30 Denis Borisov , Giuseppe Cardone

Current progress in electro-optical modulation within silicon integrated photonics, driven by the unique capabilities of advanced functional materials, has led to significant improvements in device performance. However, inherent constraints…

Optics · Physics 2025-10-30 Shahab Ramezanpour , Amr Helmy

Experimental evidence of mode-selective evanescent power coupling at telecommunication frequencies with efficiencies up to 75 % from a tapered optical fiber to a carefully designed metal nanoparticle plasmon waveguide is presented. The…

We investigate the exceptional points (EPs) in a non-Hermitian system composed of a pair of graphene sheets with different losses. There are two surface plasmon polaritons (SPP) modes in the graphene waveguide. By varying the distance…

Optics · Physics 2016-11-18 Shaolin Ke , Bing Wang , Chengzhi Qin , Hua Long , Kai Wang , Peixiang Lu

Exceptional points (EPs), i.e., non-Hermitian degeneracies at which eigenvalues and eigenvectors coalesce, can be realized by tuning the gain/loss contrast of different modes in non-Hermitian systems or by engineering the asymmetric…

Exceptional points (EPs) are degeneracies in open wave systems where at least two energy levels and their corresponding eigenstates coalesce. We report evidence of the existence of EPs in 3D plasmonic nanostructures. The systems are…

Optics · Physics 2017-02-02 Ashok Kodigala , Thomas Lepetit , Boubacar Kanté

Unidirectional wave propagation in nonreciprocal structures enables exciting opportunities to control and enhance wave-matter interactions in extreme ways. Within this context, here we investigate the possibility of using terminated…