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Published
, Published online: 23 April 2026
, doi: 10.37188/lam.2026.027
Surface-enhanced Raman scattering (SERS) is widely used for trace detection and compositional analysis of biochemical samples. Constructing multidimensionally ordered hotspots with high densities and intensities is crucial for achieving superior SERS substrate performance. Here, we propose a multilevel SERS substrate based on curvature and structural optimisation strategies. We fabricated microlenses with various curvatures via modification and etching using a temporally-shaped femtosecond laser. These lenses were decorated with wrinkles and Ag nanoparticles (AgNPs) via sequential pre-strain application and chemical deposition. Experimental and simulation results demonstrated that the coupling of the wide-field electric field induced by the microlens with the localised plasmonic hot spots on the AgNPs and wrinkles enhanced the localised surface electric field. Curvature-optimised microlenses can increase the wide-field electric fields. The fabricated SERS substrates achieved a low minimum detection limit of 10−11 M and an enhancement factor of approximately 1.22 × 107. These substrates can be employed to detect thiram fungicide on crops using two different methods (in situ detection and solution-assisted detection), demonstrating potential for operating efficiently under different usage conditions.
Published
, Published online: 22 April 2026
, doi: 10.37188/lam.2026.045
Overcoming the trade-off between a wide field of view (FOV) and compactness remains a central challenge for integrating near-infrared (NIR) imaging into smartphones and AR glasses. Existing refractive NIR optics cannot simultaneously support ultrawide angles above 100° and ultrathin total track lengths (TTL) below 5 mm, fundamentally limiting their integration into portable devices. Herein, we present a wafer-level-manufactured meta-aspheric lens (MAL) that simultaneously achieves a 101.5° FOV, 3.39 mm TTL, and F/1.64 aperture within a compact volume of 0.02 cm3. Unlike previous hybrid systems that rely on separate refractive and diffractive components, the proposed MAL introduces a fully integrated architecture that provides a compact form factor. This integration also simplifies fabrication by enabling high-throughput production via micrometre-level precision alignment and bonding on a single wafer, which requires only one dicing step and no additional mechanical fixtures. Furthermore, the design process incorporates manufacturability and enables metalens dispersion modelling, ensuring that the experimental performance matches simulation results. We validated the MAL method using both direct and computational imaging experiments. Despite its small form factor, our scalable MAL demonstrated strong NIR imaging performance in eye tracking, blood vessel imaging, and computational pixel super-resolution tasks. This scalable MAL technology establishes a new benchmark for high-performance miniaturised NIR imaging, and opens the door for next-generation smartphones and AR optical systems.
Published
, Published online: 21 April 2026
, doi: 10.37188/lam.2026.039
3D printed contact lenses have emerged as promising candidates for advanced ocular applications due to their customizable design and functional versatility. In this study, a novel conformal auxetic-inspired metamaterial ocular disc architecture was developed using digital light processing (DLP), a high-resolution vat photopolymerization technique, and fabricated using an in-house hydrogel formulation. The printed disc was systematically evaluated for its mechanical, optical, and physicochemical performance. Mechanical testing confirmed excellent elasticity and durability, with the hydrated hydrogel exhibiting a tensile modulus of ~0.71 MPa, matching the range of commercial soft contact lenses. Laser profilometry revealed a smooth surface topology essential for user comfort, achieving a root mean square roughness (Rq) of 1.78 µm, a nearly 98% reduction compared to conventionally printed hemispherical lenses. Contact angle measurements (64° hydrated) indicated favorable wettability. Optical characterization exhibited high light transmittance, averaging ~83% across the visible spectrum in the hydrated state. Hydration related properties, including swelling kinetics, water content, and gel fraction, confirmed effective water uptake and retention, supporting oxygen permeability. FTIR spectroscopy validated the chemical integrity of the polymer network, while DSC/TGA analysis confirmed thermal stability up to 300 °C. Furthermore, rheological evaluation indicated a stable viscoelastic profile with notable self-healing behavior. Collectively, this study establishes a 3D printed hydrogel-based conformal metamaterial contact lens platform, offering a promising pathway for the development of next-generation smart ocular devices via additive manufacturing.
Published
, Published online: 20 April 2026
, doi: 10.37188/lam.2026.037
Subwavelength photonic structures and metamaterials provide revolutionary approaches for controlling light. The inverse design methods proposed for fabricable subwavelength structures are vital for the development of new photonic devices. However, most existing inverse design methods cannot realise direct mapping from optical properties to photonic structures; instead, they rely on forward simulation methods to perform iterative optimization. In this study, we exploit the powerful generative abilities of artificial intelligence and propose a practical inverse design method based on latent diffusion models. Our method directly maps the optical properties to structures without requiring forward simulation and iterative optimization. In this case, the given optical properties can serve as ‘prompts’ and guide the constructed model to ‘draw’ the required photonic structures correctly. Simulations and experiments show that our direct-mapping-based inverse design method can generate fabricable subwavelength photonic structures with high fidelity while following the given optical properties, such as the transmission power, phase, and polarisation responses. This may influence the methods used for optical design and significantly accelerate the research and manufacturing of new photonic devices.
Published
, Published online: 17 April 2026
, doi: 10.37188/lam.2026.040
Femtosecond laser writing offers exceptional flexibility and spatial selectivity, enabling the customization of multifunctional integrated devices with nano-scale resolution. This study introduces a novel approach for fabricating nanohole-clad waveguides with ultra-high depth-to-diameter ratios using femtosecond laser writing combined with spherical-aberration-enhanced focal stretching and selective wet etching. This technique not only achieves record depth-to-diameter ratios (>50 000:1) with nanoholes (diameter: 30-500 nm, depth: 1 500 μm) but enables the creation of functional photonic waveguides. The integration of nanoholes into the waveguide structure provides a platform for multi-functional integrated devices, demonstrating significant tunable optical properties. By adjusting pulse energy and axial focal stitching, the diameter of the nanoholes can be tuned from 30 nm to 500 nm with high precision. Further, fluorescent probes embedded within the nanoholes provide a demonstration of optical sensing capabilities, as the waveguide effectively guides light to excite the probes, generating strong detectable signals. The submicron precision achieved through the process ensures high-quality waveguiding with 10.9 dB mode purity, while centimeter-scale periodic arrays exhibit excellent phase uniformity (deviation <3.9%). This work demonstrates the potential of femtosecond laser writing to directly fabricate high-aspect-ratio nanostructures and integrate functional photonic devices on substrates, opening up new possibilities for multi-functional photonics and sensor applications.
Microcavity-enhanced optoelectronic fiber photoacoustic spectroscopy for ppb-level trace gas sensing
Published
, Published online: 16 April 2026
, doi: 10.37188/lam.2026.028
Photoacoustic spectroscopy is a highly sensitive analytical technique for trace chemical detection in gaseous and liquid phases. Conventional systems relying on free-space optics face limitations in light-matter interaction efficiency and electronic integration. To address this, we developed a miniaturized, ultrasensitive photoacoustic spectroscopy gas sensor by integrating a thermally drawn multi-material optoelectronic fiber, a T-type resonant photoacoustic cell, and a MEMS microphone at the fiber tip. This system enables amplified light-gas interactions and simultaneous electrical signal acquisition, achieving ppb-level detection within seconds using sub-microliter sample volumes (0.02 mL). By leveraging mass-producible optoelectronic fibers and MEMS technology, this work establishes a new class of optical sensors featuring compact size, ultrahigh sensitivity, environmental robustness, and scalable multiplexed detection capabilities for harsh environments.
Published
, Published online: 23 March 2026
, doi: 10.37188/lam.2026.009
Autofocus is essential for high-throughput real-time scanning in microscopic imaging. Traditional methods rely on complex hardware or iterative hill-climbing algorithms. Recent learning-based approaches exhibited remarkable efficacy in one-shot settings, circumventing the need for hardware modifications or iterative mechanical lens adjustments. However, in this study, we highlight a significant challenge wherein the richness of the image content can significantly affect autofocus performance. When the image content is sparse, previous autofocus methods, whether traditional hill-climbing or learning-based, tend to fail. To address this limitation, we propose a content-importance-based solution, termed "SparseFocus", featuring a novel two-stage pipeline. The first stage assesses the importance of the regions within the image, whereas the second stage calculates the defocus distance from the selected important regions. This approach can handle autofocus issues across all levels of content sparsity (dense, sparse, or extremely sparse). To validate our approach and benefit the research community, we acquire a large-scale dataset comprising millions of labelled, defocused images encompassing dense, sparse, and extremely sparse scenarios. The experimental results demonstrate that SparseFocus surpasses existing methods, effectively handling all levels of content sparsity. Moreover, we develop an advanced one-shot autofocus-enhanced whole-slide imaging system (osa-WSI) based on SparseFocus, coupled with an efficient image-stitching protocol for large-scale imaging and online motion path planning. The system demonstrates strong performance in real-world applications. All codes and datasets will be released upon publication.
Published
, Published online: 15 April 2026
, doi: 10.37188/lam.2026.026
We propose a high-precision assembly technique for realizing high-resolution nano- to microscale displays using a trapped-assembly approach that integrates a doctor-blade-based ink-delivery system with dielectrophoresis (DEP)-induced assembly. Octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) were coated onto the pixel-defined layer (PDL) to promote ink trapping and confine fin-LEDs within individual pixels during assembly. Key process parameters—including the viscosity and dielectric properties of the ink solvent, speed and number of blade passes, blade-to-substrate gap, and applied DEP voltage and frequency—were systematically optimised, as these parameters affect solvent confinement of the solvent and fin-LED assembly behavior. Under optimised conditions, achieved through precise control of solvent polarity, DEP force and torque, and doctor-blading parameters, all 400 pixels were successfully assembled. Statistical analysis revealed that 90% of the pixels contained 12-20 fin-LEDs, with an average of 16.3 fin-LEDs per pixel and a standard deviation of 3.5. The overlap ratio was limited to 8%, and 92% of the fin-LEDs were accurately assembled, of which 95% established contact with the p-GaN surface. Electroluminescent devices fabricated using the assembled fin-LEDs exhibited bright and uniform emission across the entire pixel array, confirming their excellent assembly quality and high electrical reliability. The DEP-based trapped-assembly method provides a reliable and scalable strategy for the practical integration of nano- to microscale LEDs in next-generation high-resolution display technologies.
Published
, Published online: 08 April 2026
, doi: 10.37188/lam.2026.006
Optical coherence tomography (OCT), a well-established technique for ophthalmic diagnostics, is now expanding into non-ophthalmic applications, such as dermatology, oncology, and dentistry. OCT signals contain numerous microstructure-sensitive features, including attenuation, speckle statistics, and optical phase. To facilitate the development of feature applications for various tasks and their integration into emerging use cases, we developed a no-code multimodal OCT-integrated online platform for scientific research. This paper describes the capabilities of the developed online platform: realistic digital phantoms of OCT datasets for tuning and benchmarking signal processing approaches; advanced processing of OCT scans to extract feature maps. Several variants of multimodal OCT signal processing have been implemented, including optical attenuation, speckle contrast, depolarisation ratio, strain, and elastographic imaging. This is the first OCT multimodal platform designed to support scientific research aimed at developing various custom-tuned applications, such as disease classification, tumour margin isolation, and severity prediction. We demonstrated the application of this platform for downstream cancer diagnostics using real data from human brain tissue, skin, endometrial tissue, and murine tumour models.
Published
, Published online: 08 April 2026
, doi: 10.37188/lam.2026.030
Histopathology, the study and diagnosis of disease through analysis of tissue samples, is an indispensable part of modern medicine, especially for treating diseases like cancer. However, the practice is time consuming and labor intensive, a circumstance that compels increasing efforts to improve the process and develop new approaches. One of the prospective histopathology techniques involves mapping changes in the polarization state of light being scattered by the tissue, but the conventional implementation relies on bulky polarization optics and is relatively slow. Here, we report the design, fabrication and characterization of a dedicated metasurface polarimeter operating at the wavelength of 640 nm that enables fast parallel (simultaneous) measurements of the Stokes parameters and degree of polarization, with the Stokes parameters determined with ±2% accuracy. To validate its use for digital histopathology we assemble a miniaturized device integrated with the metasurface polarimeter and map polarization state changes in a tissue phantom designed to mimic a biopsy with a cancerous inclusion. The results obtained are compared with those obtained by using a commercial polarimeter, indicating a great potential of metasurface polarimeter based devices and suggesting several possibilities for significant improvement of the current device implementation. We believe that, with these improvements in place, the considered metasurface polarimeter based devices will be ready for practical histopathology applications in clinical environments.
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