Nontrivial coupling of light into a defect: the interplay of nonlinearity and topology

Xia, Shiqi; Jukić, Dario; Wang, Nan; Smirnova, Daria; Smirnov, L. A.; Tang, Liqin; Song, Daohong; Szameit, Alexander; Leykam, Daniel; Xu, Jingjun; Chen, Zhigang; Buljan, Hrvoje

doi:10.1038/s41377-020-00371-y

Cited by 96 publications

(77 citation statements)

References 72 publications

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“…Specifically, under self-focusing nonlinearity, the output exhibits strong localization into the initially excited interface waveguide (Fig. 5f), which corresponds to generation of a nonlinear Tamm-like surface state (or discrete semi-infinite-gap soliton) not of topological origin [15,25]. In contrast, under strong self-defocusing nonlinearity, the output pattern becomes strongly delocalized and spreads into the bulk (Fig.…”

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confidence: 98%

Weakly nonlinear topological gap solitons in Su–Schrieffer–Heeger photonic lattices

et al. 2020

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We study both theoretically and experimentally the effect of nonlinearity on topologically protected linear interface modes in a photonic Su-Schrieffer-Heeger (SSH) lattice. It is shown that under either focusing or defocusing nonlinearity, this linear topological mode of the SSH lattice turns into a family of topological gap solitons. These solitons are stable. However, they exhibit only a low amplitude and power and are thus weakly nonlinear, even when the bandgap of the SSH lattice is wide. As a consequence, if the initial beam has modest or high power, it will either delocalize, or evolve into a soliton not belonging to the family of topological gap solitons. These theoretical predictions are observed in our experiments with optically induced SSH-type photorefractive lattices.

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confidence: 98%

Weakly nonlinear topological gap solitons in Su–Schrieffer–Heeger photonic lattices

et al. 2020

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“…Indeed, we use a general theoretical protocol (developed recently in ref. 44 ) for interpreting the dynamics in nonlinear topological systems, where both inherited and emergent topological phenomena may arise. The calculated nonlinear eigenvalue spectrum (at Z = 50) for the nontrivial SSH lattice is plotted in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Quite generally, for a weak nonlinearity and practically any excitation, the symmetries responsible for the nontrivial topology of the 2D SSH model are broken 54 . However, in a weakly nonlinear system, the topological properties can persist as they are inherited from the corresponding linear system 44 . This is the origin of the weak nonlinear coupling between the corner and the bulk modes discussed above.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear control of photonic higher-order topological bound states in the continuum

Bongiovanni

Jukić

et al. 2021

Light Sci Appl

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Higher-order topological insulators (HOTIs) are recently discovered topological phases, possessing symmetry-protected corner states with fractional charges. An unexpected connection between these states and the seemingly unrelated phenomenon of bound states in the continuum (BICs) was recently unveiled. When nonlinearity is added to the HOTI system, a number of fundamentally important questions arise. For example, how does nonlinearity couple higher-order topological BICs with the rest of the system, including continuum states? In fact, thus far BICs in nonlinear HOTIs have remained unexplored. Here we unveil the interplay of nonlinearity, higher-order topology, and BICs in a photonic platform. We observe topological corner states that are also BICs in a laser-written second-order topological lattice and further demonstrate their nonlinear coupling with edge (but not bulk) modes under the proper action of both self-focusing and defocusing nonlinearities. Theoretically, we calculate the eigenvalue spectrum and analog of the Zak phase in the nonlinear regime, illustrating that a topological BIC can be actively tuned by nonlinearity in such a photonic HOTI. Our studies are applicable to other nonlinear HOTI systems, with promising applications in emerging topology-driven devices.

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“…For example, high‐order topological insulators, [ 3–5 ] non‐Hermitian topological steering, [ 6–8 ] and topological lasers. [ 9–11 ] Specifically, the Su−Schrieffer−Heeger (SSH) model is a popular model revealing nontrivial topology in one‐dimensional (1D) systems, [ 12 ] in which the chiral zero modes exhibit robustness against local structural fluctuations and disorders that plays an important role in light transport, [ 13–15 ] lasing, [ 16,17 ] and photonic integration, [ 18–20 ] etc. Recently, the notion of topological phases has been extended to Floquet systems where the Hamiltonian is periodic in time, H ( t + T ) = H ( t ), with T is the driving period.…”

Section: Introductionmentioning

confidence: 99%

Gauge‐Induced Floquet Topological States in Photonic Waveguides

Song

Chen

et al. 2021

Laser & Photonics Reviews

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Tremendous efforts are devoted to the research of exotic photonic topological states, in which Floquet systems suggest new engineered topological phases and provide a powerful tool to manipulate the optical fields. Here, a gauge‐induced topological state localized at the interface between two gauge‐shifted Floquet photonic lattices with the same topological order is demonstrated. The quasienergy band structures reveal that these interface modes belong to the Floquet π modes, which are further found to enable an asymmetric topological transport of this interface mode thanks to the flexible control of the Floquet gauge. The intriguing propagations of the gauge‐induced topological states are experimentally verified in a silicon waveguides platform at near‐infrared wavelengths, which show broadband working wavelengths and robustness against the structural fluctuations. This work provides a new route in manipulating optical topological modes by Floquet engineering and inspires more possibilities in photonics integrations.

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Nontrivial coupling of light into a defect: the interplay of nonlinearity and topology

Cited by 96 publications

References 72 publications

Weakly nonlinear topological gap solitons in Su–Schrieffer–Heeger photonic lattices

Weakly nonlinear topological gap solitons in Su–Schrieffer–Heeger photonic lattices

Nonlinear control of photonic higher-order topological bound states in the continuum

Gauge‐Induced Floquet Topological States in Photonic Waveguides

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