Advanced Optical Materials最新文献

Hierarchical Twisted Supramolecular Structures

Cellulose derivatives reveal their hidden chiral complexity: free-standing cholesteric films exhibit coexisting left- and right-handed twisted structures that respond in opposite ways to mechanical strain. This hierarchical chiral organization not only couples optical and mechanical responses but also enables spontaneous shape recovery and reversible tuning of circular dichroism—unveiling a new level of mechanoresponsive control in solvent-free thermotropic cellulose systems. More details can be found in the Research Article by Maria Helena Godinho and co-workers (DOI: 10.1002/adom.202502728).

The ongoing race to miniaturize photonic integrated circuits demands optical cavities not only exhibiting high quality-factors (Q), but that are also compact and robust. However, in conventional photonic crystal (PhC) designs, achieving high-Q typically requires large structures with extended periodicity, which increases sensitivity to fabrication-induced disorder as it multiplies imperfections, hampering reproducibility. In this work, PhC slab cavities as small as 4 × 4 µm², achieving relatively high Q comparable to conventional large L3 cavities, despite occupying only a fraction of their footprint, are numerically and experimentally demonstrated. These structures are obtained through an optimization process that introduces an aperiodic, yet highly controlled, pattern of holes surrounding the cavity. Multiple replicas of each design are fabricated, and near-field optical characterization, confirming both the Q enhancement and a marked improvement in spectral reproducibility, is performed. The reduced variability across nominally identical devices highlights the potential of engineered aperiodicity as a robust and scalable design strategy for high Q nanophotonic cavities, suitable for dense on-chip integration, paving the way for robust integration in active photonic platforms.

Conventional vision sensors based on the von Neumann architecture suffer from high latency, energy inefficiency, and redundant data transfer, which limit their ability to meet the growing demands of artificial visual perception. Inspired by the human retina, where excitatory and inhibitory signaling pathways cooperate to enhance contrast, suppress noise, and adapt to dynamic environments, all-optical modulated bidirectional responsive synaptic (AOMBRS) devices have emerged as a promising solution. In this review, recent advances in AOMBRS devices, covering diverse material platforms and their underlying mechanisms, are summarized. Further, emerging applications in optical logic operations, associative learning, neuromorphic computing, and adaptive vision, which demonstrate the promise of AOMBRS devices in bridging biological vision and artificial intelligence, are highlighted. Finally, the critical challenges related to material stability, device performance, and large-scale integration are discussed, and future opportunities for advancing next-generation neuromorphic hardware are outlined.

Visible and near-infrared (VIS-NIR) spectral imaging is vital for agriculture, food safety, and biomedical applications. Conventional spectral imaging relies on precision optical components with limited environmental adaptability, whereas computational spectral imaging employs advanced processing algorithms to simplify hardware architecture while improving system flexibility. However, developing compact, high-performance, low-cost snapshot systems remains challenging, especially in mask fabrication and real-time imaging algorithms. In this work, a low-cost snapshot VIS-NIR spectral imager based on an on-chip all-dielectric weak-confined Fabry–Pérot filter array and a deep learning-based reconstruction approach is presented. Using single-exposure patterning and the Cumulative Attention Transformer with Random Mask (CATRM) algorithm, the manufacturing process is streamlined while the reconstruction accuracy is enhanced. The system achieves high spatial resolution (100.17 lp mm⁻¹) and maintains isotropic imaging fidelity, while reconstructing full-field (2048 × 2048 × 61) hyperspectral data at 12.35 fps. The spectral accuracy of the imager is confirmed by spectral imaging of two traditional Chinese medicinal herbs, Astragalus membranaceus and Coptis chinensis, which shows over 99.1% cosine similarity between the system and a commercial scanning hyperspectral imager. Moreover, the broad application prospects are validated by non-destructive sugar content prediction in mangoes. The integrated imager design enables compact, cost-effective VIS-NIR spectral imaging for diverse application scenarios.

Materials with large second-order nonlinearities are crucial for next-generation integrated photonics. Spontaneously oriented organic thin films prepared by physical vapor deposition offer a promising poling-free and scalable approach. This study investigates molecular engineering strategies to enhance the second-order nonlinear response of derivatives based on the donor-acceptor molecule 2-(4'-diphenylaminobiphenyl-4-yl)quinoxaline-6,7-dicarbonitrile (TPA-QCN). Four derivatives incorporating modifications designed to increase molecular hyperpolarizability (β) or promote favorable orientation are synthesized and characterized. The most successful modification, intramolecular bridge-locking, simultaneously increases hyperpolarizability and enhances spontaneous orientation by reducing detrimental electrostatic interactions during deposition. It leads to a significant enhancement of the second-order nonlinear response, achieving off-resonance $��{\chi }_{31}^{�\left(�2�\right)�}�\approx �16�$ pm V⁻¹ and $��{\chi }_{33}^{�\left(�2�\right)�}�\approx �18�$ pm V⁻¹ at 1550 nm, a twofold improvement over the parent TPA-QCN. Analysis combining nonlinear optical measurements, surface potential measurement, optical anisotropy, and density functional theory calculations indicate that improved molecular orientation, rather than increased β alone, is the primary driver for the enhanced performance in the leading derivatives. These findings demonstrate the effectiveness of targeting molecular orientation via structural design and position spontaneously oriented organic films as compelling poling-free candidates for integrated nonlinear photonic applications where the increased electrode-induced optical losses, fabrication complexity and footprint are a critical limitation.

Polarization-sensitive photodetection based on anisotropic/anisotropic, namely all-anisotropic, van der Waals heterostructures (vdWHs) offers transformative potential for miniaturized multifunctional optoelectronics, yet progress is hindered by low polarization ratios (<10) and an incomplete understanding of performance-governing mechanism. Here, these limitations are addressed by engineering type-I Ta₂PdS₆/ReSe₂ vdWHs with orientation-tailored architectures, featuring a unilateral depletion region to modulate carrier transport dynamics. By systematically comparing parallel and vertical stacking configurations, the parallel configuration delivers exceptional self-powered performance under 635 nm light illumination: responsivity of 482 mA/W, specific detectivity of 1.0 × 10¹² Jones, and polarization ratio of 11.21, nearly one order of magnitude higher than its vertical counterpart and other reported all-anisotropic vdWHs. Mechanistic studies attribute these enhancements to synergistic effects of optimized carrier pathways along the armchair directions of both materials and a strengthened built-in electric field within a narrowed transition region, collectively suppressing interlayer nonradiative recombination and boosting efficient photocarrier extraction. Integration into polarized single-pixel imaging and polarization-coded optical communication systems demonstrates the versatility of this approach. These results establish orientation engineering as a powerful strategy for unlocking the full potential of 2D all-anisotropic vdWHs in a next-generation multifunctional optoelectronic platform.

The based on WO₃ electrochromic devices (ECDs) is developing, but it remains a challenge to design all-solid-state ECDs that cover the VIS–IR spectrum with high stability, fast switching rate, and a wide tunable emissivity range. It is important to design ECD that synergistically modulates the smart thermodynamic cover in a wide spectral range. Here, the bilateral modulation process provides a new strategy for the design and fabrication of VIS–IR ECDs. The bilateral modulation of all-solid-state ECD with an ITO/Ti-doped ITO/LiNbO₃/NiO_x/ITO-glass structure that has a low energy consumption (± 1.5 V) is reported. Its modulation is based on the localized surface plasmon resonance (LSPR) and the traditional electrochromic processes. IR is regulated on the Ti-doped ITO, VIS is regulated on the NiO_x. The Δε of the ECD in the range of 1.25–2.5, 3–5, 8–14, 2.5–25, 14–25, and 1.25–28.6 µm are 0.50, 0.51, 0.48, 0.35, 0.33, and 0.32, respectively, and ΔT is 18.9% at 489 nm. It has a fast switching time of 0.5 and 2.7 s, and a cycling life of 10⁴ cycles in IR. It also highlights the potential of combining two modulation principles in one ECD to achieve dual-band modulation of VIS–IR under the same processing voltage.

The development of plasmonics and related applications in the terahertz range faces limitations due to the intrinsic high electron density of the standard metals. All-dielectric systems are profitable alternatives, which allows for customized modulation of the optical response upon doping. Here, plasmon-based hyperbolic metamaterials are realized stacking doped III-V semiconductors that have been shown to be optically active in the terahertz spectral region. By using a multi-physics multi-scale theoretical approach, the role of doping and geometrical characteristics (e.g., thickness, composition, grating) in the modulation of high-k plasmon-polariton modes across the metamaterial is unraveled.

Understanding the interplay between magnetic ordering and light emission is crucial for developing magneto-optical technologies. However, this phenomenon is poorly understood since observations of this coupling vary significantly across materials. In this context, hybrid organic-inorganic metal halide perovskites (HOIPs) that incorporate Mn²⁺ ions are a chemically and structurally tunable platform for exploring this phenomenon, since they exhibit magnetic ordering and photoluminescence (PL) emission. Here, two antiferromagnetic Mn-based HOIPs with different organic cations are studied, resulting in distinct lattice stiffness, Mn²⁺-Mn²⁺ distance, and octahedral distortion. Temperature-dependent PL excitation spectroscopy reveals changes in crystal field splitting energy and Racah parameters well above the Néel temperature (T_N), indicating the emergence of Mn²⁺-Mn²⁺ magnetic interactions prior to reach long-range magnetic ordering. These variations align with the observed changes in temperature-PL evolution. The compound with a more rigid lattice shows stronger changes closer to T_N, suggesting combined effects of magnetic polarons and spin-canting. In contrast, magnetic modifications induced by magnetic polarons prevail in the HOIP with a softer lattice. These results reveal the complexity of the magneto-optical coupling in Mn-based HOIPs and provide new insights into this field extensible to other 2D materials that exhibit this phenomenon with potential for advanced magneto-optical applications.

Advanced imaging, sensing, andtelecommunications demand high-performance, low-power broadband photodetectorswith improved responsivity and spectral range. This work fills a key gap bydemonstrating p-Si/n-Sn(S_xSe_1-x)₂ verticalheterojunction (HJ) photodetectors with asymmetric Ag (Φ = 4.28 eV) /graphene(Φ = 4.7 eV) electrodes to optimize carrier dynamics and band alignment. Fourdevice configurations; symmetric (D1: Ag/HJ/Ag, D2: Gr/HJ/Gr) and asymmetric(D3: Gr/HJ/Ag, D4: Ag/HJ/Gr) were systematically investigated to elucidate therole of electrode asymmetry in enhancing photoresponse. D4 achievesstate-of-the-art responsivity of 1.01 A/W, external quantum efficiency (EQE) of 197.29%, and specific detectivity of 3.75 × 10¹¹ Jones at 635 nm(130 µW/cm², +3 V), driven by efficient hole injection at Ag/p-Si (Φ_Bp ≈ 0.87 eV) and electron extraction at Gr/n-SnSSe (Φ_Bn ≈ 0.38 eV), augmented by photoconductive gain from trap-assisted carrier multiplication.The D3 device operates self-powered, producing 16.6 nA at 0 V under white lightdue to a strong built-in field from the Gr/Ag work-function contrast. Thedevices show broadband response (505–940 nm) with high sensitivity performanceeven at low light intensities (<150 µW/cm²). This work presentsa scalable, material-efficient route to high-efficiency self-poweredphotodetectors for energy-efficient broadband sensing.