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The phenomenon of PT (parity- and time-reversal) symmetry breaking is conventionally associated with a change in the complex mode spectrum of a non-Hermitian system that marks a transition from a purely oscillatory to an exponentially…

We study Bragg-induced power oscillations in Fourier space between a pair of optical resonant transverse modes propagating through a periodic PT symmetric lattice, represented by a refractive index that includes gain and loss in a balanced…

Optics · Physics 2017-11-29 Paulo A. Brandão , Solange B. Cavalcanti

We explore a new class of Distributed Feedback (DFB) structures that employ the recently-developed concept of Parity-Time (PT) symmetry in optics. We demonstrate that, based on PT-symmetric pure reflective volume gratings, vertical cavity…

Optics · Physics 2015-10-29 H. F. Jones , Mykola Kulishov

Symmetry breaking is an effective tool for tuning the transport and topological properties of 2D layered materials. Among these materials, twisted bilayer graphene (TBG) has emerged as a promising platform for new physics, characterized by…

Mesoscale and Nanoscale Physics · Physics 2024-06-06 Cunyuan Jiang , Matteo Baggioli , Qing-Dong Jiang

We investigate the nontrivial characteristics of modulational instability (MI) in a system of Bragg gratings with saturable nonlinearity. We also introduce an equal amount of gain and loss into the existing system which gives rise to an…

Pattern Formation and Solitons · Physics 2023-05-24 K. Tamilselvan , A. Govindarajan , I. Inbavalli , T. Alagesan , M. Lakshmanan

The ability to manipulate cavity resonant modes is of critical importance in laser physics and applications. By exploiting the parity time (PT) symmetry, we propose and experimentally realize a single-mode FP laser with improved output…

Parity-time (PT) symmetry and broken in micro/nano photonic structures have been investigated extensively as they bring new opportunities to control the flow of light based on non-Hermitian optics. Previous studies have focused on the…

Optics · Physics 2022-07-20 Qi Zhang , Yun Ma , Qi Liu , Xinchen Zhang , Yali Jia , Limin Tong , Qihuang Gong , Ying Gu

The broken and unbroken phases of PT and supersymmetry in optical systems are explored for a complex refractive index profile in the form of a Scarf potential, under the framework of supersymmetric quantum mechanics. The transition from…

Quantum Physics · Physics 2021-07-05 Adipta Pal , Subhrajit Modak , Aradhya Shukla , Prasanta K. Panigrahi

We address propagation of light in nonlinear twisted multi-core fibers with alternating amplifying and absorbing cores that are arranged into the PT - symmetric structure. In this structure, the coupling strength between neighboring cores…

A class of structures based on PT PT-symmetric Bragg gratings in the presence of both gain and loss is studied. The basic concepts and properties of parity and time reversal in one-dimensional structures that possess idealised material…

Twisted bilayer graphene (tBLG) provides a fascinating platform for engineering flat bands and inducing correlated phenomena. By designing the stacking architecture of graphene layers, twisted multilayer graphene can exhibit different…

Parity-time-symmetric ($\mathcal{PT}$-symmetric) optical waveguide couplers have become a key component for integrated optics. They offer new possibilities for fast, ultracompact, configurable, all-optical signal processing. Here, we study…

Optics · Physics 2015-09-14 Wiktor Walasik , Natalia M. Litchinitser

The application of parity-time (PT) symmetry in optics, especially PT-symmetry breaking, has attracted considerable attention as a novel approach to controlling light propagation. Here, we report optical limiting by two coupled optical…

When a monochromatic beam of light propagates through a periodic structure with the incident angle satisfying the Bragg condition, its Fourier spatial spectra oscillates between the resonant modes situated on the edges of the Brillouin…

Optics · Physics 2018-02-09 Paulo A. Brandão , Solange B. Cavalcanti

This study introduces the Bragg Frequency Convertor, a spatial-temporal-periodic grating that extends the concept of conventional Bragg gratings into the dynamic domain to achieve pure parametric frequency conversion. By time-modulating…

Optics · Physics 2026-03-10 Sajjad Taravati

The spectral characteristics of a fiber Bragg grating (FBG) with a transversely inhomogeneous refractive index profile, differs con- siderably from that of a transversely uniform one. Transmission spectra of inhomogeneous and asymmetric…

We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently-prepared four-level N-type atomic system. By appropriately tuning the pertinent atomic parameters, the onset of PT-symmetry…

The strain fields of periodically buckled graphene induce a periodic pseudo-magnetic field (PMF) that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudo-magnetic field, we determine the…

Mesoscale and Nanoscale Physics · Physics 2020-12-29 S. P. Milovanović , M. Anđelković , L. Covaci , F. M. Peeters

We investigate the spectral properties and dynamical features of a time-periodic PT-symmetric Hamiltonian on a one-dimensional tight-binding lattice. It is shown that a high-frequency modulation can drive the system under a transition…

Quantum Physics · Physics 2013-06-06 Giuseppe Della Valle , Stefano Longhi

Parity-time (PT) symmetry is a new method to get single mode operation in lasers, mostly, micro-ring lasers. In this study, we propose and experimentally demonstrate an electrically pumped PT symmetric Fabry-Perot (FP) laser which can work…

Optics · Physics 2020-11-20 Zeqiu Liu , Peng Huang , Ming Li , Ninghua Zhu