Time reversal (T) invariant topological insulator is widely recognized as one of the fundamental discoveries in condensed matter physics, for which most fascinating hallmark perhaps a spin based protection, total cancellation scattering conduction electrons with certain spins on surface. Recently, it has created paradigm shift insulators, from electronics to photonics, phononics well mechanics, bringing about not only involved new physics but also potential applications robust wave...

By using optical phase modulators in a fiber-optical circuit, we theoretically and experimentally demonstrate large control over the spectrum of an impinging signal, which may evolve analogously to discrete diffraction spatial waveguide arrays. The modulation acts as photonic gauge potential frequency dimension, realizing efficient central bandwidth combs. We achieve 50 GHz shift threefold expansion comb, well analogue various refraction phenomena, including negative perfect focusing domain,...

Exceptional points (EPs) are branch point singularities of self-intersecting Riemann sheets, and they can be observed in a non-Hermitian system with complex eigenvalues. It has been revealed recently that dynamically encircling EPs by adiabatically changing the parameters composed lossy optical waveguides could lead to asymmetric (input-output) mode transfer. However, length had considerable ensure adiabatic evolution. Here we demonstrate change along smaller loop utilizing moving EPs,...

Photonic gauge potentials, including scalar and vector ones, play fundamental roles in emulating photonic topological effects for enabling intriguing light transport dynamics. While previous studies mainly focus on manipulating propagation uniformly distributed here we create a series of gauge-potential interfaces with different orientations nonuniform discrete-time quantum walk demonstrate various reconfigurable temporal-refraction effects. We show that lattice-site interface the potential...

We investigate the exceptional points (EPs) in a non-Hermitian system composed of pair graphene sheets with different losses. There are two surface plasmon polaritons (SPP) modes waveguide. By varying distance between and chemical potential graphene, EPs appear as eigenvalues, that is, wave vectors coalesce. The cross conversion eigenmodes variation geometric phase can be observed by encircling EP parametric space formed parameters graphene. At same time, certain input SPP mode may lead to...

Abstract Bloch oscillations (BOs) were initially predicted for electrons in a solid lattice to which static electric field is applied. The observation of BOs solids remains challenging due the collision scattering and barrier tunnelling electrons. Nevertheless, analogies electron photons, acoustic phonons cold atoms have been experimentally demonstrated various systems. Recently, frequency dimension proposed studied by using an optical micro-resonator, provides unique approach controlling...

Dynamic localization (DL) of photons, i.e., the light-motion cancellation effect arising from lattice's quasi-energy band collapse under a synthetic ac-electric-field, provides powerful and alternative mechanism to Anderson for coherent light confinement. So far only low-order DLs, corresponding weak ac-fields, have been demonstrated using curved-waveguide lattices where waveguide's bending curvature plays role ac-field as required in original Dunlap-Kenkre model DL. However, inevitable...

We investigate the supermodes in arbitrary layers of graphene sheets, which are collective guided modes formed by coupling surface plasmon polaritons (SPPs) each sheet. In terms dispersion relation, we analyse effective indexes and mode profiles supermodes. Numerical simulations reveal that can be well approximated linear superposition SPPs individual sheets. Among all possible supermodes, there is an interesting one possessing both lowest propagation loss shortest wavelength. The supermode...

We propose a graphene Ramsey interferometer to study the non-reciprocal phase shift and modulation of surface plasmon polaritons (SPPs). The is constructed by spatially separated pair that can support two SPP modes. By dynamically modulating conductivity graphene, modes will undergo uncompleted cross conversion an additional shift. When adopting regions in interferometer, converted mode jump back with nonreciprocal which be controlled length or phase. interfere throughout unconverted one,...

Here we create an effective electric field force for photon in a synthetic frequency lattice to control the spectrum of light. The is created based on optical waveguide modulator which dynamic index modulation can induce photonic transitions between adjacent sites. We show that wave vector mismatch during and periodic distribution phase be mapped into linear-varying periodically driven gauge potential, gives rise constant harmonic oscillating force, respectively. Under different combinations...

We investigate Rabi oscillations of surface plasmon polaritons in the graphene waveguide array consisting spatially separated multilayers each period. The plasmonic supermodes generated period should couple to other, yielding Bloch modes multilayer (GMA). By introducing spatial modulation dielectric permittivity between graphene, both direct and indirect transitions may occur, resulting cross conversion co- counter-propagating different bands. As number depends on that layers GMA, there be...

Non-Hermitian lattice systems with unconventional transport phenomena and topological effects have attracted intensive attention recently. Non-Hermiticity is generally introduced by engineering on-site gain/loss distribution or inducing asymmetric couplings applying an imaginary gauge field. Here, we extend the concept of non-Hermitian lattices from spatial to frequency dimension emulate various arising coupling in synthetic dimension. The created introducing complex potentials through...

Landau-Zener tunneling (LZT), i.e., the nonadiabatic transition under strong parameter driving in multilevel systems, is ubiquitous physics, providing a powerful tool for coherent wave control both quantum and classical systems. While previous works mainly focus on LZT between two energy bands time-invariant crystals, here, we construct synthetic time-periodic temporal lattices from coupled fiber loops demonstrate dc- ac-driven LZTs periodic Floquet bands. We show that display distinctive...

We investigate the discrete temporal Talbot effect in a synthetic mesh lattice by employing two coupled fiber loops with different lengths. The consists of round-trip number and time delay pulse trains propagating loops. occurs only as incident train one loop has period that is 1, 2, or 4 folds interval corresponding to length difference By varying splitting ratio coupler connecting loops, band structure can be engineered so do distance, which further tuned imposing an initial linear phase...

We investigate the plasmonic nanofocusing of terahertz waves in tapered graphene multilayers separated by dielectrics. The effect is significantly enhanced multilayer taper compared with that a single layer due to interlayer coupling between surface plasmon polaritons. results are optimized choosing an appropriate number and field amplitude has been 620 folds at λ = 50 μm. Additionally, structure can slow light group velocity ~1/2815 speed vacuum. Our study provides unique approach compress...

We investigate the temporal and spectral evolutions of finite-energy Airy pulses in presence power-law optical potentials. The potentials are generated by time-dependent pumped light, which propagates together with a highly nonlinear fiber. show that intrinsic acceleration can be modified an external force stems from linear potential, hence unidirectional frequency shift realized. When triangle potential is employed, pulse will exhibit self-splitting both domains. Additionally, as parabolic...

Here we investigate the Bloch oscillations (BOs) in a photonic spectral lattice created with four-wave mixing Bragg scattering (FWM-BS). By injecting signal and two pumps different frequencies into silicon nitride waveguide, can be for generated idlers through successive FWM-BS. The phase-mismatch during FWM-BS acts as an effective force that induces BOs lattice. Both oscillation period amplitude are determined by magnitude of force. With cascaded processes, spectrum experiences directional...

We investigate the topological phase transition between Type-I and Type-II Weyl points (WPs) in a composite three-dimensional lattice composed of two-dimensional brick-wall waveguide array synthetic frequency dimension created by dynamic modulation. By imposing different modulation amplitudes phases two sublattices, we can break either parity or time-reversal symmetry realize WPs. As is truncated to have edges, Fermi-arc surface states will emerge, which propagate opposite directions for WPs...

By using a fiber loop with phase modulator, we simulate the refraction and reflection effects of optical pulses at heterointerface in time domain, which is formed by abruptly varying modulation depth or frequency. When variation periodically imposed on pulse, vertical may lead to total internal reflection. The temporal can be controlled setting different Bloch wave vectors incidence. As occurs specific moment during pulse propagation, horizontal interface appears, negative splitting domain...

A waveguide coupler under both phase and intensity modulation is proposed to generate a non-Hermitian Su-Schrieffer-Heeger lattice in frequency dimension. By varying the period phase, we can manipulate on-site potential of realize anisotropic coupling supermodes waveguides. The artificial electric field associated with also be introduced simultaneously. Zener tunneling demonstrated system manifests an irreversibly unidirectional conversion between odd even supermodes. efficiency optimized by...

Abstract Parity‐time (PT) and anti‐parity‐time (anti‐PT) symmetries have provided important guiding principles in the research of non‐Hermitian physics. However, realizations anti‐PT symmetry photonic systems usually rely on optical nonlinearities indirect‐coupling approaches. Here, they apply channel interference principle mediated by synthetic gauge‐flux biasing open‐cavity to construct symmetries. It is shown that a specific π ‐flux into looped‐resonator array can force frequency...

Super-Bloch oscillations (SBOs) are amplified versions of direct current (dc)-driving Bloch realized under the detuned dc- and alternating (ac)-driving electric fields. A unique feature SBOs is coherent oscillation inhibition via ac-driving renormalization effect, which dubbed as collapse SBOs. However, previous experimental studies on have only been limited to weak regime, has not observed. Here, by harnessing a synthetic temporal lattice in fiber-loop systems, we push ac-field into...

We investigate the Bloch mode conversion of surface plasmon polaritons in a periodic array graphene pairs with each consisting two separated parallel sheets. The employment pair as unit cell yields modes belonging to different bands. By periodically modulating permittivity dielectrics between along propagation direction, interband transitions occur and will alternatively couple other, similar traditional Rabi oscillations quantum systems. indirect can also be observed through introducing...