Hasil untuk "Applied optics. Photonics"

S. Molesky, Zin Lin, Alexander Piggott et al.

Recent advancements in computational inverse-design approaches — algorithmic techniques for discovering optical structures based on desired functional characteristics — have begun to reshape the landscape of structures available to nanophotonics. Here, we outline a cross-section of key developments in this emerging field of photonic optimization: moving from a recap of foundational results to motivation of applications in nonlinear, topological, near-field and on-chip optics. Starting with a desired optical output it is possible to use computational algorithms to inverse design devices. The approach is reviewed here with an emphasis on nanophotonics.

Long Chang, Xiaoshun Jiang, Shiyue Hua et al.

F. Yesilkoy, Eduardo Arvelo, Yasaman Jahani et al.

K. Koshelev, Yutao Tang, K. Li et al.

Nonlinear nanostructured surfaces provide a paradigm shift in nonlinear optics with new ways to control and manipulate frequency conversion processes at the nanoscale, also offering novel opportunities for applications in photonics, chemistry, material science, and biosensing. Here, we develop a general approach to employ sharp resonances in metasurfaces originated from the physics of bound states in the continuum for both engineering and enhancing the nonlinear response. We study experimentally the third-harmonic generation from metasurfaces composed of symmetry-broken silicon meta-atoms and reveal that the harmonic generation intensity depends critically on the asymmetry parameter. We employ the concept of the critical coupling of light to the metasurface resonances to uncover the effect of radiative and nonradiative losses on the nonlinear conversion efficiency.

Krzysztof Tyszka

Abstract A silicon photonic deep optical neural network integrating convolutional and fully connected layers with on-chip optoelectronic nonlinear activations operates with partially coherent light to achieve high-speed, energy-efficient, end-to-end inference. This demonstration establishes a functional and scalable platform for evaluating complete optical neural processing, representing another step toward specialised, ultrafast photonic architectures beyond electronics.

C. C. Wanjura, F. Marquardt

The increasing size of neural networks for deep learning applications and their energy consumption create a need for alternative neuromorphic approaches, e.g., using optics. Current proposals and implementations rely on physical non-linearities or opto-electronic conversion to realise the required non-linear activation function. However, there are significant challenges with these approaches related to power levels, control, energy-efficiency, and delays. Here, we review our scheme [Nat. Phys. 20, 1434–1440 (2024)] for a neuromorphic system that relies on linear wave scattering and yet achieves non-linear processing with a high expressivity. The key idea is to encode the input in physical parameters that affect the scattering processes. Moreover, gradients needed for training can be directly measured in scattering experiments. We propose an integrated-photonics implementation based on racetrack resonators that achieves high connectivity with a minimal number of waveguide crossings. Our work opens the door to a new, easily implementable paradigm of neuromorphic computing that can be widely applied in existing state-of-the-art, scalable platforms, such as optics, microwave and electrical circuits.

Xinyi Xie, Luqman Munir, Yannis Mantas Paulus

Retinal laser therapy has been a mainstay for treating proliferative diabetic retinopathy, retinal vascular disease, and retinal breaks since 1961. However, conventional millisecond photocoagulation can cause permanent scarring and procedure discomfort, motivating the development of damage-sparing approaches that preserve the neurosensory retina. Clinically, panretinal photocoagulation remains effective for proliferative disease but trades off peripheral visual field and night vision. This review synthesizes development, mechanisms, and clinical evidence for laser modalities, including short-pulse selective retinal therapy (SRT), subthreshold diode micropulse (SDM), and pattern-scanning photocoagulation. We conducted a targeted narrative search of PubMed/MEDLINE, Embase, Web of Science, and trial registries (1960–September 2025), supplemented by reference list screening. We prioritized randomized/prospective studies, large cohorts, systematic reviews, mechanistic modeling, and relevant preclinical work. Pulse duration is the primary determinant of laser–tissue interaction. In the microsecond regime, SRT yields retinal pigment epithelium (RPE)-selective photodisruption via microcavitation and uses real-time optoacoustic or OCT feedback. SDM 100–300 µs delivers nondamaging thermal stress with low duty cycles and titration-based dosing. Pattern-scanning platforms improve throughput and tolerance yet remain destructive photocoagulation. Feedback-controlled SRT shows anatomic/functional benefit in chronic central serous chorioretinopathy and feasibility in diabetic macular edema. SDM can match threshold macular laser for selected DME and may reduce anti-VEGF injection burden. Sub-nanosecond “rejuvenation” lasers show no overall benefit in intermediate AMD and may be harmful in specific phenotypes. Advances in delivery, dosimetry, and closed-loop feedback aim to minimize collateral damage while retaining therapeutic effect. Key gaps include head-to-head trials (SRT vs. PDT/SDM), standardized feedback thresholds across pigmentation and devices, and long-term macular safety to guide broader clinical adoption.

P. Clini, R. Angeloni, M. D’Alessio et al.

The paper presents the digital representation and virtual experience of Borgo Storico Seghetti Panichi, a cultural site distinguished by the close interplay between architecture and landscape. The project was developed using an integrated approach that brings together 3D survey techniques, immersive technologies, and Artificial Intelligence (AI). Consolidated techniques such as Terrestrial Laser Scanning (TLS) and UAV-based photogrammetry were adopted to generate accurate 3D models of the Villa, the Roccolo, the Church, and the surrounding historic park. Moreover, preliminary tests with 3D Gaussian Splatting (GS) were conducted to evaluate its potential for photorealistic and real-time visualization in Cultural Heritage (CH) contexts. The different digital representations were embedded in a Virtual Reality (VR) application designed to offer an engaging and educational user experience. The immersive environment includes interactive components such as the digital replicas of the buildings and the historic park, audio narration, and a virtual keyboard connected to a Large Language Model (LLM). This system enables users to formulate questions in natural language and receive dynamic, context-specific responses within the VR environment, fostering active learning and customized exploration. The development process included a structured pipeline from survey data to VR implementation, with specific focus on optimization for standalone headsets. User evaluation tests confirmed the effectiveness of the experience in terms of realism, interaction, and accessibility, while also identifying areas for further improvement.

Huanwen Chen, Wenxing Yu, Xinrong Xu et al.

The propagation of multiple ultraintense femtosecond lasers in underdense plasmas is investigated theoretically and numerically. We find that the energy merging effect between two in-phase seed lasers can be improved by using two obliquely incident guiding lasers whose initial phase is $\pi$ and $\pi /2$ ahead of the seed laser. Particle-in-cell simulations show that due to the repulsion and energy transfer of the guiding laser, the peak intensity of the merged light is amplified by more than five times compared to the seed laser. The energy conversion efficiency from all incident lasers to the merged light is up to approximately 60 $\%$ . The results are useful for many applications, including plasma-based optical amplification, charged particle acceleration and extremely intense magnetic field generation.

Ori Nefesh, Heleni Krelman, K. Levi et al.

The interaction between light and vapors in the presence of magnetic fields is fundamental to many quantum technologies and applications. Recently, the ability to geometrically confine atoms into periodic structures has enabled the creation of chip-scale, micromachined hybrid atomic-diffractive optical elements. However, applying magnetic fields to such structures remains largely unexplored, offering potential for both fundamental and applied insights. Here, we present measurements of an atomic-diffractive optical element subject to magnetic fields. In contrast to the well-known polarization rotation in a Faraday medium, these diffractive atomic elements exhibit additional, rapidly oscillating rotation terms, which we validate both theoretically and experimentally. Moreover, we find that the introduction of spatially varying magnetic fields leads to a reduction in fringe visibility, which can be leveraged for gradiometric applications. Together, these effects establish a chip-scale platform where diffraction and quantum sensing are inseparably co-engineered, unveiling previously inaccessible regimes of atom–photon–magnetic interaction. By probing the magneto-optic response of periodically confined vapors, our results lay the groundwork for integrated smart-cell magnetometers and open new avenues for flat-optics-enabled quantum photonic devices.

P. Yadav, R. Chahal, Aman Singh

Thermophotovoltaic (TPV) systems rely on spectrally selective reflectors to enhance conversion efficiency by maximizing photon flux above the photovoltaic bandgap while suppressing sub-bandgaps thermal losses. This work presents a numerical analysis and simulation of SiO2/TiO2 multilayer photonic crystal Distributed Bragg’s Reflectors (DBRs) tailored to the GaAs bandgap (≈ 872 nm). Transfer Matrix Method (TMM) was applied to investigate optical properties of the structure with layer’s thickness, number of periods, and refractive index contrast. Investigation demonstrate that optimized multilayer design exhibit narrowband reflection peaks centered around 800 – 1000 nm (≈ 200 nm), closely matched to the GaAs photovoltaic cutoff wavelength, with reflectivity exceeding 0.99. Beyond 1000 nm, reflectivity is strongly suppressed, minimizing energy reflections associated with unusable infrared photons. The stability analysis with angular and polarization suggests the robust performance over a wide range of angle of incidences, which are critical requirement for practical and efficient TPV operations. The numerical and simulation findings highlight the potential of SiO2/TiO2 1D photonic crystal thermally stable, tunable selective reflectors, offering a viable pathway for efficiency enhancement in GaAs-based TPV systems. Full Text: PDF References Z. Omair, S. Hooten, V. Menon, P. Oduor, K-K Choi, A.K. Dutta, "Broadband mirrors for thermophotovoltaics", Opt. Express 32, 11000 (2024). CrossRef LaPotin, A., Schulte, K.L., Steiner, M.A. et al. "Thermophotovoltaic efficiency of 40%", Nature 604, 287 (2022). CrossRef T. Inoue, T. Suzuki, K. Ikeda, T. Asano, S. Noda, "Near-field thermophotovoltaic devices with surrounding non-contact reflectors for efficient photon recycling", Opt. Express 29, 11133 (2021). CrossRef C. Juseok, H. Koohee, K. Jung, "Enhanced near infrared reflectance of TiO2/SiO2/TiO2 multilayer structure using a base-catalyzed SiO2 film", Thin Solid Films. 569, 100 (2014). CrossRef A. Kotbi, W.E. Hakim, P. Barroy, et al. "Selecting the state of shape memory alloys by optical filtering", Opt Quant Electron 57, 534 (2025). CrossRef J. Xi, E. Schubert, D. Ye, T. Lu, S.H. Lin, J. Juneja, "Very low-refractive-index optical thin films consisting of an array of SiO2 nanorods", Optics Lett. 31, 601 (2006). CrossRef G. Christidis, O. Fabrichnaya, S. Koepfli, E. Poloni,J. Winiger,Y. Fedoryshyn, A. Gusarov, M. Ilatovskaya, I. Saenko, G. Savinykh, V. Shklover, J. Leuthold, "Photonic response and temperature evolution of SiO2/TiO2 multilayers". J. Mater. Sci. 56 (2021). CrossRef D. Kim, K.M. Kim, H. Han, et al. "Ti/TiO2/SiO2 multilayer thin films with enhanced spectral selectivity for optical narrow bandpass filters". Sci Rep 12, 32 (2022). CrossRef G. Hwang, G. Bak, Y. Kim, S.H. Jung, H. Na, Y.J. Jung, "Highly Reflective Organic/Inorganic Hybrid 1D Photonic Crystals Based on Silane-Functionalized TiO2 Nanoparticles for Colorimetric Humidity and Alcohol Vapor Sensing", ACS Omega 10(32), 36582 (2025). CrossRef S. Chen, T. Zhu, F. Juan, Y. Zhu, J. Xu, K. Chen, "High-temperature stable and efficient broadband solar absorber based on Si/metal plasmonic structures", Solar Energy. 276. 112664 (2024). CrossRef F.K. Mbakop, R.Z. Falama, F. Wu, A. Ayang, S.N. Essiane, L. Leontie, N. Djongyang, F. Iacomi, "Angular dependence of photonic band gap and omni-directional reflection in one-dimensional photonic crystal applied to a thermophotovoltaic device", Results in Optics, 14, 100594 (2024). CrossRef Z. Zhou, O. Yehia, P. Bermel, "Integrated photonic crystal selective emitter for thermophotovoltaics", J. Nano photonics. 10(1), 016014 (2016). CrossRef M.B. Panish, H.C. Casey, "Temperature Dependence of the Energy Gap in GaAs and GaP", J. Appl. Phys. 40(1), 163 (1969). CrossRef M. Suemitsu, T. Asano, T. Inoue, S. Noda, "High-Efficiency Thermophotovoltaic System That Employs an Emitter Based on a Silicon Rod-Type Photonic Crystal", ACS Photonics 7(1), 80 (2020). CrossRef L. Farah, A.B. Hadjira, A. Mehadji, "A Novel 1.31 um Narrow-band TE-Mode filter Design based on PBG Shift in 2D Photonic Crystal Slab", Photonics Lett. Pol., 8(3), 82 (2016). CrossRef N.L. Kazanskiy, M.A. Butt, "One-dimensional photonic crystal waveguide based on SOI platform for transverse magnetic polarization-maintaining devices", Photonics Lett. Pol.,12(3), 85 (2020). CrossRef O.H. Jaworska, S. Ertman, "Photonic Bandgaps In Selectively Filled Photonic Crystal Fibers", Photonics Lett. Pol.,9(3), 79 (2017). CrossRef D.M. Mead, "Wave Propagation In Continuous Periodic Structures: Research Contributions From Southampton, 1964-1995", Journal Of Sound And Vibration, 190(3),495 (1996). CrossRef

Chuanshuo Wang, Chao Meng, Xianglong Mei et al.

Compared to conventional lasers limited to generating static modes, mode-switchable lasers equipped with adjustable optics significantly enhance the flexibility and versatility of coherent light sources. However, most current approaches to achieving mode-switchable lasers depend on conventional, i.e., inherently bulky and slow, optical components. Here, we demonstrate fiber lasers empowered by electrically actuated intracavity microelectromechanical system (MEMS)–based optical metasurface (MEMS-OMS) enabling mode switching between fundamental Gaussian and vortex modes at ~1030 nm. By finely adjusting the voltage applied to the MEMS mirror, high-contrast switching between Gaussian (l = 0) and vortex (l = 1, 2, 3, and 5, depending on the OMS arrangement) laser modes is achieved, featuring high mode purities (>95%) and fast responses (~100 microseconds). The proposed intracavity MEMS-OMS–enabled laser configuration provides an at-source solution for generating high-purity fast-switchable laser modes, with potential applications ranging from advanced optical imaging to optical tweezers, optical machining, and intelligent photonics.

Amirhossein Amjad, Xiaojun Xian

This review has explored optical sensors and their important role in non-invasive transdermal biomarker detection. While electrochemical sensors have been thoroughly studied for biomarker tracking, optical sensors present a compelling alternative due to their high sensitivity and selectivity, multiplex capabilities, cost-efficiency, and small form factor. This review examines the latest advancements in optical sensing technologies for transdermal biomarker detection, such as colorimetry, fluorescence, surface plasmon resonance (SPR), fiber optics, photonic crystals, and Raman spectroscopy. These technologies have been applied in the analysis of biomarkers present in sweat and skin gases, which are essential for non-invasive health monitoring. Furthermore, the review has discussed the challenges and future perspectives of optical sensors in in transdermal biomarker detection. The analysis of various sensor types and their applications highlights the transformative potential of optical sensors in enhancing disease diagnostics and promoting proactive health management.

A. Di Francescantonio, Alessandra Sabatti, H. Weigand et al.

Electro-optical modulation is essential in optical signal processing and laser technology, yet modulators based on the Pockels effect in flat optics lag behind bulk and integrated platforms in efficiency and speed. We bridge this gap realizing a metasurface based on lithium niobate (LiNbO₃) on insulator that leverages on resonances with quality-factor as high as 8000 to achieve fast electrical modulation of both linear and nonlinear optical properties. LiNbO3, well known for its high nonlinear susceptibility and wide transparency window across the infrared and visible spectrum, is employed to realize an asymmetric, one-dimensional array of nanowires, exhibiting resonances with linewidth <0.2 nm. The metasurface achieves a reflectivity modulation around 0.1, with a modulation efficiency, defined as relative modulation per applied Volt, larger than 0.01 V−1 on a −3 dB (−6 dB) bandwidth of about 800 MHz (1.4 GHz). Additionally, we demonstrate more than one order of magnitude intensity modulation of the second harmonic seeded by a continuous-wave laser, with a modulation efficiency of about 0.12 V−1. This dual modulation capability, rooted in the interplay between optical resonances and electric field manipulation, holds significant potential for cutting-edge applications in high-speed photonics, nonlinear optics, and reconfigurable communication systems. A lithium niobate nonlocal metasurface with high-Q (~8000) resonances demonstrates efficient GHz-rate reflectivity modulation (~0.1) and one order of magnitude second harmonic modulation using sub-10V driving voltages, offering promising applications in high-speed nanophotonics.

Aofei Mao, Sarah Fess, Nada Kraiem et al.

Since 2001, 3D microfabrication based on two‐photon polymerization (TPP) has drawn extensive attention and interest in biology, optics, photonics, material science, and high‐energy physics. The in‐volume fabrication capability due to the threshold behavior of two‐photon absorption enables TPP higher flexibility compared with other nanofabrication techniques. However, as determined by the in‐volume fabrication feature as well as various reaction dynamics, the writing characteristics of TPP, such as throughput, accuracy, surface quality, and fabrication capability, are still limited. Herein, a comprehensive study is performed on the spatiotemporal behavior of reaction dynamics during TPP fabrication, mainly focusing on spatiotemporal characteristics of radical diffusion, photothermal effect, microscale mechanics, and voxel stacking process. Based on the study, a nonsequential fabrication method is established to simultaneously improve key writing characteristics of TPP and realize sharp features, high speeds, large overhang structure, and smooth surfaces. The method established in this work can be applied to improve the performance of functional devices for various fields.

Abdullah, Ghauss ur Rahman, J. F. Gómez-Aguilar

Sahil Pontula, Sachin Vaidya, C. Roques-Carmes et al.

Nonlinear optics has become the workhorse for countless applications in classical and quantum optics, from optical bistability to single photon pair generation. However, the intrinsic weakness of optical nonlinearity has meant that large input powers and weak output powers are often a necessity in nonlinear frequency conversion. Here, motivated by recent advances in using non-Hermitian photonics and gain/loss engineering to enable non-reciprocal light transport, we explore how the interplay between non-Hermiticity and optical nonlinearity leads to a fundamentally new regime of nonlinear frequency conversion. We show how non-Hermitian coupling between discrete frequency modes can result in non-reciprocal flow of energy in the frequency dimension, closely resembling the non-Hermitian skin effect (NHSE). Applying our theory to a multimode nonlinear cavity supporting cascaded nonlinear processes, we create an asymmetric infrared (IR) comb that features a ``skin'' frequency mode populated with efficiency exceeding 85\%. Furthermore, we demonstrate how three-wave mixing processes in the non-reciprocal infrared comb we generate enables terahertz (THz) generation exceeding the Manley-Rowe limit. We then show how the non-reciprocal frequency conversion is robust against cavity defects and disorder that cause random fluctuations in the dissipation rate for different modes. Moreover, in certain regimes, the nonlinear, non-Hermitian system supports stable limit cycles that can enable multimode pulsing with picosecond pulse widths and GHz repetition rates. Finally, we explore how the system can be applied to generate simultaneous IR and THz frequency combs, potentially unlocking novel applications in spectroscopy and metrology.

Juanna Jiang, Xinmin Fu, Jie Yang et al.

Due to nontrivial field topologies, polarization vortices carrying polarization singularities have attracted increasing interest in the fields of optics and photonics. However, the conventional methods for generation of polarization vortcies still suffer from the complexity and the heavy bulk. In this work, taking advantage of spin‐decoupled geometric phase in metasurfaces, a novel method is proposed to generate polarization vortices with customizable topological charges. By tailoring spin‐decoupled geometric phases generated by the metasurface, distinct helical phase profiles can be imparted to left‐ and right‐handed circularly polarized components. Consequently, two scalar vortices with different topological charges can be simultaneously generated in the two orthogonal circular polarization components, leading to the generation of the polarization vortices with the needed topological charges and the diverse morphologies. Both simulation and experimental results well demonstrate the method. Owing to the nondispersive feature of geometric phases, the designed metasurface works well in a wide frequency band. The proposed method contributes a reliable and feasible solution for customizing the generation of polarization vortices, which can be further transposed to other frequencies and applied to information encoding and polarization detection etc.

M. Montuori

The technical provisions for protecting built cultural heritage originate from the interdisciplinary disciplines of architecture and engineering, which mutually operate despite encountering specific challenges. Therefore, the lack of adaptable applications capable of integrating the management of complex data originating from various sources has prompted the development of an Internet-of- Things-based application that enables "on-the-fly" data acquisition and information processing from distant locations, records the timeline on a remote desktop, and sends email and brief early warning text messages of alarm when a programmed threshold is exceeded. Furthermore, a dedicated platform is designed to administer and grant users access to a database containing data gathered through the analysis of diagnostic non-destructive methods (i.e., archival documentation, image processing for infrared thermography, acoustic and ultrasonic tomography, and so forth). The system architecture is distinguished by a distributed intelligence consisting of multiple nodes, which enables the remote processing of locally acquired information. The arrangement was strategically planned to optimize the utilization of the wireless digital bus connecting sensors and data storage units. This enables the examination of the case study to be conducted remotely, with all collected data accessible in a suitable semantic web environment. The data can then be analysed and interpreted following the investigation's context. Hence, the present paper aims to provide a detailed vision of the tests conducted on the case study, showcasing the prototype demonstrator's stress test, the analysis layout, and the project's architecture.

Xiaolin Zhuang, Wei Zhang, Kemeng Wang et al.

Active terahertz beam steering based on mechanical deformation of the LCE metasurface tuned infrared pump