Polarization-insensitive terahertz third-harmonic generation from degenerate pairs of mirror-coupled super-BICs

Applied Physics Letters, Journal Year: 2024, Volume and Issue: 125(8)

Published: Aug. 19, 2024

Resonant nanostructures have emerged as versatile photonic platforms for boosting optical nonlinear responses on a subwavelength scale their ability to confine intense electromagnetic fields while relaxing the phase-matching requirements. Recent significant advances in this field are associated with utilization of non-radiative eigenmodes above light cone, termed bound states continuum (BICs), which provide unique mechanism trapping realize excitation ultrahigh quality (Q) factor resonances. Nevertheless, current studies BICs predominantly focus symmetry-protected (SP-BICs), whose requires symmetry breaking, and Q factors limited by fabrication imperfections. Here, we demonstrate simple feasible scheme creating degenerate pairs mirror-coupled super-BICs harnessing magnetic dipole resonances coupled mirror images adjacent metal films. Unlike trivial SP-BICs, showcases huge enhancement resilient against By combining resonance engineered radiative loss, obtain perfect absorber near-unity absorption ultra-narrow bandwidth at critical coupling condition. Finally, numerically terahertz (THz) regime, polarization-insensitive highly efficient third-harmonic generation benefiting from maximum localized within absorber. Our work not only paves way toward unlocking full potential BIC but also promise valuable insights developing THz optoelectronic devices metadevices across wide range fields.

Language: Английский

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Varifocal Metalenses: Harnessing Polarization-Dependent Superposition for Continuous Focal Length Control

Nano Letters, Journal Year: 2023, Volume and Issue: 23(22), P. 10432 - 10440

Published: Nov. 13, 2023

Traditional varifocal lenses are bulky and mechanically complex. Emerging active metalenses promise compactness design flexibility but face issues like mechanical tuning reliability nonlinear focal length due to additional medium requirements. In this work, we propose a metalens based on superimposing light intensity distributions from two orthogonal polarization states. This approach enables continuous precise control within the visible spectrum, while maintaining relatively high focusing efficiencies (∼41% in simulation ∼28% measurement) quality. experimental validation, exhibited flexible tunability, with continuously adjustable between spatial positions upon variation of incident angle. The MTF results showed contrast reproduction sharp imaging, Strehl ratio >0.7 for all angles. With compactness, flexibility, quality, proposed holds potential diverse applications, advancing adaptive versatile optical devices.

Language: Английский

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

ACS Nano, Journal Year: 2024, Volume and Issue: 18(9), P. 7064 - 7073

Published: Feb. 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.

Language: Английский

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Longitudinal field controls vector vortex beams in anisotropic epsilon-near-zero metamaterials

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: April 23, 2025

Abstract Structured light plays an important role in metrology, optical trapping and manipulation, communications, quantum technologies nonlinear optics. Here, we demonstrate alternative approach for the manipulation of vector beams carrying longitudinal field components using metamaterials with extreme anisotropy. Implementing vectorial spectroscopy, show that propagation complex inhomogeneous polarization is strongly affected by interplay metamaterial anisotropy transverse structure beam. This phenomenon especially pronounced epsilon-near-zero regime, exclusively realised polarized along axis, influencing interaction fields metamaterial. The requirements on balance between to maintain a singularity at beam axis allow control modal content, filtering diffraction effects tailoring spatial distributions. understanding opens new opportunities applications microscopy, information encoding, biochemical sensing technologies.

Language: Английский

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Deep Learning Empowered Parallelized Metasurface Computed Tomography Snapshot Spectral Imaging

Advanced Materials, Journal Year: 2025, Volume and Issue: unknown

Published: April 24, 2025

Abstract Snapshot spectral imaging is an emerging technology for fast data acquisition in dynamic environments, capturing high‐volume spatial‐spectral information a single snapshot. However, it suffers from bulky cascading optics and cannot be directly used space‐restricted scenarios such as endoscope‐assisted brain microsurgery real‐time cellular tissue imaging. In this work, ultracompact strategy of parallelized metasurface computed tomography empowered by generative deep learning proposed, which can effectively reduce the volume snapshot cm 3 scale to sub‐mm while retaining high resolution speed so that above‐mentioned pain point problem well addressed. The system comprises seven multifunctional sub‐metasurfaces simultaneously acquiring multi‐angle projection integration target, uses system‐calibrated spread functions wavelength spatial position distributions, incorporates adversarial neural network reconstruction multiplexed images. Experimental results show achieved 38 ms with 10 nm range 450–650 nm. This technique paves way into various highly miniaturized microscopy endoscopic systems applications advanced medical diagnosis.

Language: Английский

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