Extremely broadband, on-chip optical nonreciprocity enabled by mimicking nonlinear anti-adiabatic quantum jumps near exceptional points

Choi, Young-Sun; Hahn, Choloong; Yoon, Jae Woong; Song, Seok Ho; Berini, Pierre

doi:10.1038/ncomms14154

Cited by 99 publications

(74 citation statements)

References 33 publications

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“…[35]), where the encircling loop is fixed once the samples are fabricated. The topological structure of our system is also more complex than previous ones [34][35][36][37][38] due to the presence of two EPs, and the locations of the EPs can be specified by choosing appropriate system parameters. To demonstrate this point, we show in Fig.…”

Section: In Situ Control Of Encircling Loops With An External Fieldmentioning

confidence: 99%

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Dynamically Encircling Exceptional Points: In situ Control of Encircling Loops and the Role of the Starting Point

et al. 2018

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The most intriguing properties of non-Hermitian systems are found near the exceptional points (EPs) at which the Hamiltonian matrix becomes defective. Due to the complex topological structure of the energy Riemann surfaces close to an EP and the breakdown of the adiabatic theorem due to non-Hermiticity, the state evolution in non-Hermitian systems is much more complex than that in Hermitian systems. For example, recent experimental work [Doppler et al. Nature 537, 76 (2016)] demonstrated that dynamically encircling an EP can lead to chiral behaviors, i.e., encircling an EP in different directions results in different output states. Here, we propose a coupled ferromagnetic waveguide system that carries two EPs and design an experimental setup in which the trajectory of state evolution can be controlled in situ using a tunable external field, allowing us to dynamically encircle zero, one or even two EPs experimentally. The tunability allows us to control the trajectory of encircling in the parameter space, including the size of the encircling loop and the starting/end point. We discovered that whether or not the dynamics is chiral actually depends on the starting point of the loop. In particular, dynamically encircling an EP with a starting point in the parity-time-broken phase results in non-chiral behaviors such that the output state is the same no matter which direction the encircling takes. The proposed system is a useful platform to explore the topology of energy surfaces and the dynamics of state evolution in non-Hermitian systems and will likely find applications in mode switching controlled with external parameters.

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Section: In Situ Control Of Encircling Loops With An External Fieldmentioning

confidence: 99%

“…It was not until recently that the dynamical encircling of an EP was realized experimentally in microwave [35] and optomechanical systems [36]. The chiral behavior is expected to have promising applications in asymmetric mode switching [35,37] and on-chip nonreciprocal transmission [38].…”

Section: Introductionmentioning

confidence: 99%

Dynamically Encircling Exceptional Points: In situ Control of Encircling Loops and the Role of the Starting Point

et al. 2018

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“…Such bi-directional light transmissions in the optical waveguide can be realized by assigning a scattering matrix which is formulated as . Ports (1,2) and (3,4) of the isolator are associated with waveguide ends P1 and P2, respectively.…”

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confidence: 99%

Exceptional Point and toward Mode-Selective Optical Isolation

et al. 2020

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Dynamical encirclement of an Exceptional Point (EP) and corresponding time-asymmetric mode evolution properties due to breakdown in adiabatic theorem have been a key to range of exotic physical effects in various open atomic, molecular and optical systems. Here, exploiting a gain-loss assisted dual-mode optical waveguide that hosts a dynamical EP-encirclement scheme, we have explored enhanced nonreciprocal effect in the dynamics of light with onset of saturable nonlinearity in the optical medium. We propose a prototype waveguide-based isolation scheme with judicious tuning of nonlinearity level where one can pass only a chosen mode in any of the desired directions as per device requirement. The deliberate presence of EP enormously enhances the nonreciprocal transmission contrast even up to 40 dB over the proposed device length with a scope of further scalability. This exclusive topologically robust mode selective all-optical isolation scheme will certainly offer opportunities in integrated photonic circuits for efficient coupling operation from external sources and improve device performances. arXiv:1904.07468v1 [physics.optics]

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“…These exceptional points have many interesting applications. For example, they can be used as sensors with enhanced sensitivity [1,33], as optical omni-polarizers [34], for the creation of chiral laser modes [35], or for unidirectional light transmission [36][37][38]. Furthermore, non-Hermitian periodic lattices with nontrivial topology can be utilized as topological lasers [2][3][4].…”

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confidence: 99%

Topology and exceptional points of massive Dirac models with generic non-Hermitian perturbations

2019

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Recently, there has been a lot of activity in the research field of topological non-Hermitian physics, partly driven by fundamental interests and partly driven by applications in photonics. However, despite these activities, a general classification and characterization of non-Hermitian Dirac models that describe the experimental systems is missing. Here, we present a systematic investigation of massive Dirac models on periodic lattices, perturbed by general non-Hermitian terms. We find that there are three different types of non-Hermitian terms. For each case we determine the bulk exceptional points, the boundary modes, and the band topology. Our findings serve as guiding principles for the design of applications, for example, in photonic lattices. For instance, periodic Dirac systems with non-Hermitian mass terms can be used as topological lasers. Periodic Dirac systems with non-Hermitian anti-commuting terms, on the other hand, exhibit exceptional points at the surface, whose non-trivial topology could be utilized for optical devices. arXiv:1902.06617v2 [cond-mat.mes-hall]

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Extremely broadband, on-chip optical nonreciprocity enabled by mimicking nonlinear anti-adiabatic quantum jumps near exceptional points

Cited by 99 publications

References 33 publications

Dynamically Encircling Exceptional Points: In situ Control of Encircling Loops and the Role of the Starting Point

Dynamically Encircling Exceptional Points: In situ Control of Encircling Loops and the Role of the Starting Point

Exceptional Point and toward Mode-Selective Optical Isolation

Topology and exceptional points of massive Dirac models with generic non-Hermitian perturbations

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