Two-Dimensional Reconfigurable Non-Hermitian Gauged Laser Array.

Topological effects in photonic non-Hermitian systems have recently led to extraordinary discoveries including nonreciprocal lasing, topological insulator lasers, and topological metamaterials, to mention a few. These effects, although realized in non-Hermitian systems, are all stemming from their Hermitian components. Here we experimentally demonstrate the topological skin effect and boundary sensitivity, induced by the imaginary gauge field in a two-dimensional laser array, which are fundamentally different from any Hermitian topological effects and intrinsic to open systems.

Higher-dimensional supersymmetric microlaser arrays.

The nonlinear scaling of complexity with the increased number of components in integrated photonics is a major obstacle impeding large-scale, phase-locked laser arrays. Here, we develop a higher-dimensional supersymmetry formalism for precise mode control and nonlinear power scaling. Our supersymmetric microlaser arrays feature phase-locked coherence and synchronization of all of the evanescently coupled microring lasers-collectively oscillating in the fundamental transverse supermode-which enables high-radiance, small-divergence, and single-frequency laser emission with a two-orders-of-magnitude enhancement in energy density.

Tunable topological charge vortex microlaser.

The orbital angular momentum (OAM) intrinsically carried by vortex light beams holds a promise for multidimensional high-capacity data multiplexing, meeting the ever-increasing demands for information. Development of a dynamically tunable OAM light source is a critical step in the realization of OAM modulation and multiplexing. By harnessing the properties of total momentum conservation, spin-orbit interaction, and optical non-Hermitian symmetry breaking, we demonstrate an OAM-tunable vortex microlaser, providing chiral light states of variable topological charges at a single telecommunication wavelength.

Non-Hermitian topological light steering.

Photonic topological insulators provide a route for disorder-immune light transport, which holds promise for practical applications. Flexible reconfiguration of topological light pathways can enable high-density photonics routing, thus sustaining the growing demand for data capacity. By strategically interfacing non-Hermitian and topological physics, we demonstrate arbitrary, robust light steering in reconfigurable non-Hermitian junctions, in which chiral topological states can propagate at an interface of the gain and loss domains.

Non-Hermitian heterostructure for two-parameter sensing.

Non-Hermitian systems at exceptional point (EP) degeneracy are demonstrated to be highly sensitive to environmental perturbation. Here, we propose and theoretically investigate a novel multilayered heterostructure favoring double EPs for a unique set of material parameters at which forward- and backward-reflection coefficients vanish, respectively. Such an EP heterostructure is shown to scatter off light when system parameters are perturbed away from the degeneracies due to the effect of ambient temperature and mechanical stress fluctuations.

Supersymmetry-guided method for mode selection and optimization in coupled systems: publisher's note.

This publisher's note corrects an error in the funding section of Opt. Lett.43, 3758 (2018)OPLEDP0146-959210.

Supercharge optical arrays.

We introduce the notion of a supercharge optical array synthesized according to supersymmetric charge operators. Starting from an arbitrary array, mathematical supersymmetry transformation can be used systematically to create a zero-energy physical state below the ground state of the super-partner array. This zero mode, which is pinned deep in the mid-gap of the corresponding supercharge array owing to the square-root spectral relationship between a supercharge and a super-Hamiltonian array, is shown to be protected because of the chiral symmetry inherent to a supercharge array.

Supersymmetry-guided method for mode selection and optimization in coupled systems.

Single-mode operation of coupled optical systems, such as optical-fiber bundles, lattices of photonic waveguides, or laser arrays, requires an efficient method to suppress unwanted super-modes. Here, we propose a systematic supersymmetry-based approach to selectively eliminate modes of such systems by decreasing their lifetime relative to the lifetime of the mode of interest. The proposed method allows to explore the opto-geometric parameters of the coupled system and to maximize the relative lifetime of a selected mode.

Non-Hermitian photonics promises exceptional topology of light.

The band degeneracy, either the exceptional point of a non-Hermitian system or the Dirac point associated with a topological system, can feature distinct symmetry and topology. Their synergy will further produce more exotic topological effects in synthetic matter.

Coherent-perfect-absorber and laser for bound states in a continuum.

It is shown that two fundamentally different phenomena, the bound states in continuum and the spectral singularity (or time-reversed spectral singularity), can occur simultaneously. This can be achieved in a rectangular core dielectric waveguide with an embedded active (or absorbing) layer. In such a system a two-dimensional bound state in a continuum is created in the plane of a waveguide cross section, and it is emitted or absorbed along the waveguide core.

Waveguides with Absorbing Boundaries: Nonlinearity Controlled by an Exceptional Point and Solitons.

We reveal the existence of continuous families of guided single-mode solitons in planar waveguides with weakly nonlinear active core and absorbing boundaries. Stable propagation of TE and TM-polarized solitons is accompanied by attenuation of all other modes, i.e.

Modes and exceptional points in waveguides with impedance boundary conditions.

A planar waveguide with an impedance boundary, composed of nonperfect metallic plates, and with passive or active dielectric filling, is considered. We show the possibility of selective mode guiding and amplification when a homogeneous pump is added to the dielectric and analyze differences in TE and TM mode propagation. Such a non-conservative system is also shown to feature exceptional points for specific and experimentally tunable parameters, which are described for a particular case of transparent dielectric.