Giant ultrafast dichroism and birefringence with active nonlocal metasurfaces

Light Science & Applications, Год журнала: 2024, Номер 13(1)

Опубликована: Авг. 23, 2024

Abstract Switching of light polarization on the sub-picosecond timescale is a crucial functionality for applications in variety contexts, including telecommunications, biology and chemistry. The ability to control at ultrafast speed would pave way development unprecedented free-space optical links novel techniques probing dynamical processes complex systems, as chiral molecules. Such high switching speeds can only be reached with an all-optical paradigm, i.e., engineering active platforms capable controlling via ultrashort laser pulses. Here we demonstrate giant modulation dichroism birefringence all-dielectric metasurface, achieved low fluences beam. This performance, which leverages many degrees freedom offered by metasurfaces, obtained combining high-quality factor nonlocal resonance third-order nonlinearity dictated photogenerated hot carriers semiconductor band edge.

Язык: Английский

---

Realizing Minimally Perturbed, Nonlocal Chiral Metasurfaces for Direct Stokes Parameter Detection

ACS Nano, Год журнала: 2024, Номер 18(9), С. 7064 - 7073

Опубликована: Фев. 19, 2024

Recent development in nonlocal resonance based chiral metasurfaces draws great attention due to their abilities strongly interact with circularly polarized light at a relatively narrow spectral bandwidth. However, there still remain challenges realizing effective optical frequency demanding fabrications such as 3D-multilayered or nanoscaled geometry, which, particular, limit applications polarimetric detection high-Q spectra. Here, we study the underlying working principles and reveal important role of interaction between low-Q localized Mie metasurfaces. Based on principles, demonstrate one simplest types which directly detects set Stokes parameters without numerical combination transmitted values presented from typical This is achieved by minimally altering geometry filling ratio every constituent nanostructure unit cell, facilitating consistent-sized nanolithography for all samples experimentally targeted wavelength work provides an alternative design rule potential detection.

Язык: Английский

---

Inverse-designed metasurfaces with facile fabrication parameters

Journal of Optics, Год журнала: 2024, Номер 26(5), С. 055101 - 055101

Опубликована: Март 13, 2024

Abstract Optical metasurfaces are planar nanostructured devices that industrially attractive in part because they utilize high-throughput microelectronic fabrication techniques for implementation. It is therefore critical to develop design paradigms can balance the realization of highly efficient wavefront responses together with device manufacturability. We introduce a gradient-based framework freeform which nanoscale elements explicitly constrained feature basic shapes, nearly uniform sizes, and exceptionally low aspect ratios. In spite apparent uniformity metasurface geometric features, able nonlocal near-field optical coupling achieve extreme scattering beyond conventional methodologies. Utilizing this approach, we facile high-numerical-aperture such as beam deflectors large-area metalenses capable diffraction-limited focusing. anticipate these concepts facilitate integration into monolithic systems.

Язык: Английский

---

Electrically Tunable Topological Singularities in Excitonic Two-Dimensional Heterostructures for Wavefront Manipulation

ACS Photonics, Год журнала: 2024, Номер 11(9), С. 3554 - 3562

Опубликована: Авг. 15, 2024

Analysis of non-Hermitian photonic systems by the spectral positions their topological singularities plays a central role in design. Recently, link between phase and existing schemes for wavefront manipulation revealed that full-2π control light scattering from metasurfaces is associated with branch cut crossing on complex frequency plane. Here, we report controlling electrically tunable monolayer transition metal dichalcogenide heterostructures so as to actively change parameters. We use plane trajectories demonstrate modulation uniform reflectance, enabling dynamic beam deflection near-unity diffraction efficiency, explore in-plane coupling effects at surface. Our results can be further extended excitonic resonances platforms arbitrary exceptional point-based sensing new directions active two-dimensional nanophotonics.

Язык: Английский

---

Interactions of Fundamental Mie Modes with Thin Epsilon-near-Zero Substrates

Nano Letters, Год журнала: 2023, Номер 23(24), С. 11555 - 11561

Опубликована: Дек. 1, 2023

Extensive research has focused on Mie modes in dielectric nanoresonators, enabling the creation of thin optical devices surpassing their bulk counterparts. This study investigates interactions between two fundamental modes, electric and magnetic dipoles, epsilon-near-zero (ENZ) mode. Analytical, simulation, experimental analyses reveal that presence ENZ substrate significantly modifies these despite a large size mismatch. Electric dipole both with ∼12 THz line widths, exhibit 21 26 anticrossings, respectively, when coupled to mode, indicating strong coupling. We also demonstrate this strongly system yields notably subpicosecond nonlinear responses. Our results establish solid foundation for designing functional, nonlinear, dynamic metasurfaces materials.

Язык: Английский

---

Scalable on-chip diffractive speckle spectrometer with high spectral channel density

Light Science & Applications, Год журнала: 2025, Номер 14(1)

Опубликована: Март 20, 2025

Abstract The chip-scale integrated spectrometers are opening new avenues for a much wider range of applications than their conventional benchtop counterparts. While spectral reconstruction should be in command both resolution and bandwidth, large number channels is among the key goals spectrometer design. However, chip footprint eventually limits channel capacities well-established spectral-to-spatial mapping structures like dispersive elements, filter arrays, random media, so on. Here we suggest an alternative scheme by encoding information using on-chip diffractive metasurfaces. in-plane metasurface capable producing intensity speckles to resolve spectra. richness greatly increased scaling architecture via three layers cascaded readout realized two-dimensional imaging grating-diffracted pattern, enabling matrix spectrum reconstruction. has 70 pm over bandwidth 100 nm. Up 1400 were obtained within compact area only 150 μm × 950 μm. benchmark density up 10021 ch/mm 2 , which compares favorably against other state-of-art waveguide structures.

Язык: Английский

---

Ultra narrowband geometric-phase resonant metasurfaces

Proceedings of the National Academy of Sciences, Год журнала: 2025, Номер 122(15)

Опубликована: Апрель 7, 2025

The concept of a geometric phase has sparked revolution in photonics. Conventional space-variant polarization manipulation optical systems only results broadband phases. Recently emerged nonlocal metasurfaces show an ability to compress the operating bandwidth through modulations wavelength-dependent amplitudes. However, their phases are still and not linear, posing severe challenges realize ultra narrowband metadevices. Here, we propose demonstrate generation spatially variable resonant metasurfaces. We find that array perturbed Mie resonators is able simultaneously preserve its global symmetry local transformation. Local transformation provides pixel-level phase, whereas yields ultranarrow operation bandwidth. further reveal this can be well pinned mode by introducing additional perturbations individually define at nonresonant wavelengths. Consequently, experimentally pixelated phase-gradient metalenses with record-breaking Q factors high confidentiality. believe our general approach demonstrated will open paradigm multiplexed information encryption.

Язык: Английский

---

Enhanced the Tunable Nonlinearity of Epsilon‐Near‐Zero Nonlocal Metasurface by Quasi‐Guided Mode

Laser & Photonics Review, Год журнала: 2025, Номер unknown

Опубликована: Апрель 13, 2025

Abstract Quasi Bound states in the continuum(Q‐BIC) with high Q‐factors provide a powerful way to enhance nonlinearity of metasurfaces based on epsilon‐near‐zero (ENZ). However, Q‐BIC has only at specific wavevectors and wavelengths for given structures is very sensitive structural parameters. Here, strong nonlocal metasurface, consisting dielectric silicon disks ENZ thin film, wavelength‐tunable wide‐wavevectors proposed through coupling Brillouin zone folding‐induced quasi‐guided mode (Q‐GM) modes. All guided modes below light‐line are folded by periodic perturbations form Q‐GM wide wavevectors. Benefiting from sufficient field overlap modes, localized enhancement an anticrossing splitting 260 meV achieved. The measured nonlinear refractive index coefficient metasurface 3.8 × 10 −13 m 2 W −1 normal incidence, which three orders magnitude larger than that indium tin oxide (ITO)‐ film. Furthermore, since wide‐wavevectors, experimentally observed robustness increasing incident angles, realizing broadband tunable nonlinearity. provides promising platform enhancing wide‐angles multi‐wavelengths.

Язык: Английский

---

Nonlocal phase-change metaoptics for reconfigurable nonvolatile image processing

Light Science & Applications, Год журнала: 2025, Номер 14(1)

Опубликована: Май 6, 2025

Язык: Английский

---

High‐Efficiency Multi‐Level Beam Switching with Single‐Gate Tunable Metasurfaces Based on Graphene

Advanced Optical Materials, Год журнала: 2025, Номер unknown

Опубликована: Май 15, 2025

Abstract The growing demand for ultra‐fast telecommunications, autonomous driving, and futuristic technologies highlights the crucial role of active beam steering at nanoscale. This is essential applications like LiDAR, beam‐forming, holographic displays, especially as devices reduce in form factor. Although a device with beam‐switching capability potential candidate realizing those applications, there are only few works to realize switching reconfigurable metasurfaces tuning materials. In this paper, multi‐level dielectric metasurface theoretically presented graphene layer tuning, addressing challenges associated achieving high directivity diffraction efficiency, doing so while using single‐gate setup. For two‐level switching, directivities reached above 95%, efficiencies ≈50% operation wavelength λ 0 = 8 µm. Through quasi‐normal mode expansion, physics inverse‐designed by adjoint method illustrated, highlighting resonant modes their response charge carrier tuning. Under same design scheme, characteristics three‐level four‐level designed reported, suggesting possibility generalizing switching.

Язык: Английский

---