Light induced self-assembly of one-dimensional PT-symmetric optical system exhibiting pulling force.

Light induced self-assembly's non-contact and non-invasive nature, along with its versatility and dynamic assembly capabilities, make it particularly well-suited for the self-organization of particles. Previous self-assembly configurations are either in a static equilibrium state or in a dynamic equilibrium state driven by a pushing force. In this study, we introduce a one-dimensional parity-time symmetric (PT-symmetric) multilayer optical system consisting of balanced gain and loss, enabling the generation of a total pulling force on the structure.

Recent Progress on Optical Micro/Nanomanipulations: Structured Forces, Structured Particles, and Synergetic Applications.

Optical manipulation has achieved great success in the fields of biology, micro/nano robotics and physical sciences in the past few decades. To date, the optical manipulation is still witnessing substantial progress powered by the growing accessibility of the complex light field, advanced nanofabrication and developed understandings of light-matter interactions. In this perspective, we highlight recent advancements of optical micro/nanomanipulations in cutting-edge applications, which can be fostered by structured optical forces enabled with diverse auxiliary multiphysical field/forces and structured particles.

Manipulating mode degeneracy for tunable spectral characteristics in multi-microcavity photonic molecules.

Optical microcavities are capable of confining light to a small volume, which could dramatically enhance the light-matter interactions and hence improve the performances of photonic devices. However, in the previous works on the emergent properties with photonic molecules composed of multiple plasmonic microcavities, the underlying physical mechanism is unresolved, thereby imposing an inevitable restriction on manipulating degenerate modes in microcavity with outstanding performance. Here, we demonstrate the mode-mode interaction mechanism in photonic molecules composed of degenerate-mode cavity and single-mode cavity through utilizing the coupled mode theory.

Exciton polaritons in mixed-dimensional transition metal dichalcogenides heterostructures.

Transition metal dichalcogenides (TMDs) promise advanced optoelectronic applications thanks to their visible or near-infrared and layer-dependent bandgaps. Even more exciting phenomena happen via stacking the TMDs to form the vertical heterostructures, such as the exotic interlayer excitons in atomically rearranged bilayer TMDs, as the result of the tunable interlayer hopping of two monolayers. So far, those literature studies focus on either two-dimensional (2D) TMDs or the layered bulky three-dimensional (3D) TMDs.

Ultra-compact high-sensitivity plasmonic sensor based on Fano resonance with symmetry breaking ring cavity.

Miniaturizing optical devices with desired functionality is a key prerequisite for nanoscale photonic circuits. Based on Fano resonance, an on-chip high-sensitivity sensor, composed of two waveguides coupling with a symmetry breaking ring resonator, is theoretically and numerically investigated. The established theoretical model agrees well with the finite-difference time-domain simulations, which reveals the physics of Fano resonance.

High efficiency focusing vortex generation and detection with polarization-insensitive dielectric metasurfaces.

The optical vortex beam with an orbital angular momentum, featuring a doughnut intensity distribution and a helically structured wavefront, has received extensive attention due to its applications in nanoparticle manipulation and optical communications. In this paper, we propose high-efficiency polarization-independent vortex beam generators which are capable of transforming the arbitrarily polarized plane wave into a focusing optical vortex beam and an abruptly focusing airy vortex beam. Besides, based on holographic metasurfaces, we provide a general design scheme for detecting the topological charges.

Lifetime and nonlinearity of modulated surface plasmon for black phosphorus sensing application.

Black phosphorus surface plasmon (BPSP) is a new promising candidate material for electromagnetic field confinement at the subwavelength scale. Here, we theoretically investigated the light confinement, second-order nonlinearity and lifetimes of tunable surface plasmons in nanostructured black phosphorus nanoflakes with superstrates. The grating structure can enhance the local optical field of the fundamental wave (FW) and second harmonic wave (SHW) due to the surface plasmon resonance.

Broadband polarization resolving based on dielectric metalenses in the near-infrared.

We demonstrate a novel polarization-resolved device (PRD) with the ability to accurately resolve the polarization states via a simple measurement process. The PRD is composed of two elaborately designed metalenses, which are capable of focusing the two circularly polarized (CP) lights. Therefore, for an arbitrary polarized light (treated as a combination of the two CP lights), a discrepancy is exhibited on focusing efficiency, which inversely provides a way to calculate the ellipticity.

Confined surface plasmon of fundamental wave and second harmonic waves in graphene nanoribbon arrays.

The confined surface plasmon of fundamental wave and second harmonic wave (SHW) are investigated in graphene grating structure. The linear-optical absorption spectra with various fermi energy and carrier mobility are investigated with the finite difference time domain (FDTD) simulations and coupled mode theory (CMT). Based on the CMT, a theoretical model for the graphene grating is established to study the spectrum features of fundamental wave.

Reflective metalens with sub-diffraction-limited and multifunctional focusing.

We propose an ultra-thin planar reflective metalens with sub-diffraction-limited and multifunctional focusing. Based on the equal optical path principle, the specific phase distributions for multifunction focusing are derived. Following the formulas, on-center focusing with the characteristics of sub-diffraction-limited, high focusing efficiency (85%) and broadband focusing is investigated in detail.

Polarization-independent metalens constructed of antennas without rotational invariance.

We propose a novel approach to designing an ultrathin polarization-independent metalens (PIM) by utilizing antennas without rotational invariance. Two arrays of nanoblocks are elaborately designed to form the super cell of the PIM, which are capable of focusing right-handed circularly polarized and left-handed circularly polarized lights. With such a strategy, the PIM is able to achieve polarization-independent focusing, since the light with any polarization can be treated as a combination of the two orthogonal ones.

Tunable and high-sensitivity sensing based on Fano resonance with coupled plasmonic cavities.

Tunable and high-sensitivity sensing based on Fano resonance is analytically and numerically investigated in coupled plasmonic cavities structure. To analyze and manipulate the Fano line shape, the coupled cavities are taken as a composite cavity that supports at least two resonance modes. A theoretical model is newly-established, and its results agree well with the finite difference time domain (FDTD) simulations for the plasmonic stub-pair structure.

Annihilating optical angular momentum and realizing a meta-waveplate with anomalous functionalities.

Manipulating the polarization states of electromagnetic waves, a fundamental issue in optics, has attracted intense attention. However, most of the reported devices are either so bulky or with specific functionalities. Here we propose a conceptually new approach to design an ultra-thin meta-waveplate (MWP) with anomalous functionalities.

Plasmon-induced transparency in a single multimode stub resonator.

We investigate electromagnetically induced transparency (EIT)-like effect in a metal-dielectric-metal (MDM) waveguide coupled to a single multimode stub resonator. Adjusting the geometrical parameters of the stub resonator, we can realize single or double plasmon-induced transparency (PIT) windows in the plasmonic structure. Moreover, the consistency between analytical results and finite difference time domain (FDTD) simulations reveals that the PIT results from the destructive interference between resonance modes in the stub resonator.

Theoretical analysis and applications on nano-block loaded rectangular ring.

We propose compact and switchable optical filters based on nano-block loaded rectangular rings, and investigate the selection property numerically and theoretically. A simple and convenient phase model is established for the theoretical analysis. The dependent factors, such as the number, size, and positions of the loaded blocks, are discussed in detail.

Combined theoretical analysis for plasmon-induced transparency in waveguide systems.

We propose a novel combination of a radiation field model and the transfer matrix method (TMM) to demonstrate plasmon-induced transparency (PIT) in bright-dark mode waveguide structures. This radiation field model is more effective and convenient for describing direct coupling in bright-dark mode resonators, and is promoted to describe transmission spectra and scattering parameters quantitatively in infinite element structures by combining it with the TMM. We verify the correctness of this novel combined method through numerical simulation of the metal-dielectric-metal (MDM) waveguide side-coupled with typical bright-dark mode, H-shaped resonators; the large group index can be achieved in these periodic H-shaped resonators.

Uniform theoretical description of plasmon-induced transparency in plasmonic stub waveguide.

We investigate a classic analog of electromagnetically induced transparency (EIT) in a metal-dielectric-metal (MDM) bus waveguide coupled to two stub resonators. A uniform theoretical model, for both direct and indirect couplings between the two stubs, is established to study spectral features in the plasmonic stub waveguide, and the theoretical results agree well with the finite difference time domain simulations. Adjusting phase difference and coupling strength of the interaction, one can realize the EIT-like phenomena and achieve the required slow light effect.

Formation and evolution mechanisms of plasmon-induced transparency in MDM waveguide with two stub resonators.

We demonstrate the realization of plasmonic analog of electromagnetically induced transparency (EIT) in a system composing of two stub resonators side-coupled to metal-dielectric-metal (MDM) waveguide. Based on the coupled mode theory (CMT) and Fabry-Perot (FP) model, respectively, the formation and evolution mechanisms of plasmon-induced transparency by direct and indirect couplings are exactly analyzed. For the direct coupling between the two stub resonators, the FWHM and group index of transparent window to the inter-space are more sensitive than to the width of one cut, and the high group index of up to 60 can be achieved.