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        <title>Advanced Optical Technologies | Applied Photonics section | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/advanced-optical-technologies/sections/applied-photonics</link>
        <description>RSS Feed for Applied Photonics section in the Advanced Optical Technologies journal | New and Recent Articles</description>
        <language>en-us</language>
        <generator>Frontiers Feed Generator,version:1</generator>
        <pubDate>2026-05-13T12:30:33.893+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2025.1739755</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2025.1739755</link>
        <title><![CDATA[Performance analysis of a multi-format compatible all-optical data access method for satellite backbone-networks]]></title>
        <pubdate>2026-01-06T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Xinning Huang</author><author>Yuerong Shen</author><author>Daming Song</author>
        <description><![CDATA[Optical inter-satellite links are a promising technology for constructing satellite backbone networks, owing to their high data transmission capacity and lightweight terminals. To circumvent the data-rate bottlenecks and structural complexity associated with optical-electrical-optical conversion, all-optical signal processing is essential. This paper addresses a common challenge at the relaying nodes of satellite backbone networks: handling concurrent access requests from multiple laser links. We propose and validate an all-optical data access system based on an optical time-lens. The system demonstrates robust performance and high modulation format compatibility. It successfully processes intensity-modulated, phase-modulated, and hybrid-format inputs entirely in the optical domain. The system’s reliability is further confirmed under practical conditions, including uneven wavelength spans and unequal data rates among the accessing links. It achieves bit-error rates below 10−7 and supports optical inter-satellite link transmission distances exceeding 4,500 km, even under hybrid modulation formats. With its simple structure and high compatibility, the proposed system offers a scalable solution for future multi-format satellite backbone networks.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2025.1707828</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2025.1707828</link>
        <title><![CDATA[Near infrared spectroscopy assessment of wrist-based vascular occlusion protocols]]></title>
        <pubdate>2025-12-29T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Vanja Dvekar</author><author>Faraz Sadrzadeh-Afsharazar</author><author>Leah DeVos</author><author>Gennadi Saiko</author><author>Alexandre Douplik</author>
        <description><![CDATA[BackgroundVascular occlusion tests (VOTs) are widely used to assess microvascular function with near-infrared spectroscopy (NIRS), but protocols vary substantially, particularly in occlusion pressure and anatomical site. Most studies focus on the upper arm or thigh, with few studying distal limbs such as the wrist, highlighting the importance of standardizing wrist-based arterial occlusion pressures.MethodsTo address this gap, the present study examined the effects of two fixed occlusion pressures, 150 mmHg and 200 mmHg, applied at the wrist on the local muscle oxygenation dynamics. A total of 21 healthy participants underwent an 8-min experimental protocol comprising a 1-min baseline (no pressure), 3-min occlusion, and 4-min reperfusion period. Muscle oxygenation was continuously monitored from the thenar eminence of the occluded hand using a commercial near-infrared spectroscopy (NIRS) device (Moxy, Hutchinson, USA).ResultsReactive hyperemia responses at the two pressures were compared for five distinct metrics: amplitude of muscle oxygen saturation (SmO2)(p=0.0065), time to maximum SmO2(p=0.235), and three first-derivative features: time to peak slope (p=0.694), peak slope value (p=0.019), and full width at half maximum (FWHM) (p=0.46). Statistically significant differences were observed in amplitude of SmO2, and peak slope value. However, the temporal metrics such as time to max SmO2, time at peak slope value, and FWHM, were not significantly different.ConclusionOverall, this study supports the potential of wrist-based AOP protocols and highlights the importance of selecting appropriate occlusion pressures and anatomical sites to optimize vascular response while minimizing patient discomfort. Given the wrist’s anatomical advantages, incorporating wrist-based occlusion into daily practice and clinical assessments may enhance its translational potential as a pressure occlusion site.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2025.1693523</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2025.1693523</link>
        <title><![CDATA[A fiber-delivered, multi-line nanosecond source for single-shot spectro-polarimetric scattering measurements]]></title>
        <pubdate>2025-11-19T00:00:00Z</pubdate>
        <category>Brief Research Report</category>
        <author>Thomas Livecchi</author><author>Ben E. Urban</author>
        <description><![CDATA[We here describe a nanosecond, multi-line laser source that preserves partial linear polarization after transmission through a 100-m large-core graded-index (GRIN) fiber. The system generates narrow emission lines between 473 and 600 nm, evenly spaced by the silica Raman shift of ∼440 cm-1, from a Q-switched nanosecond pump coupled into the fiber. Despite multimode propagation, the cascaded beams emerge close to diffraction-limited Gaussian profiles due to nonlinear mode self-cleaning, while the residual pump remains multimodal. Across the emission lines, the degree of linear polarization (DoLP) ranges from 0.1 to 0.6 depending on the wavelength. As an application, we demonstrate single-shot, multiwavelength spectro-polarimetric reflectance, simultaneously measuring DoLP at all cascaded lines. To our knowledge, this is the first demonstration of wavelength-dependent polarization retention through a 100-m large-core GRIN fiber.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2025.1560454</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2025.1560454</link>
        <title><![CDATA[Numerical and experimental analysis of a side -polished single-mode fiber for refractive index sensing]]></title>
        <pubdate>2025-10-10T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Muhammad Musavir Bilal</author><author>Ajmal Thottoli</author><author>Marco Grande</author><author>Servando Lopez-Aguayo</author>
        <description><![CDATA[In this paper, we introduce a comprehensive study, based on both numerical and experimental analyses, of side polished-single mode fibers (SP-SMF) to investigate their corresponding evanescent field interaction with air and liquid analytes such as water and isopropanol (IPA). On the one hand, the SP-SMF’s optical properties are numerically studied and analyzed by using the finite element method and the beam propagation method, and we find that the alteration of analytes at the sensing region enhances the change in the refractive index (RI) of the materials. On the other hand, we designed and built an ad-hoc experimental setup to characterize the SP-SMF when air, water, and IPA are introduced into the SP region. The sensitivity is measured as 1.207 V/RIU. The performance in terms of effective RI and transmittance are reported to show how these SP-SMFs can be efficiently used for calculating the liquid RI. The simulation and experimental results display the significant performance of the SP-SMF as a valuable sensing element.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2025.1560084</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2025.1560084</link>
        <title><![CDATA[Progress in integrated and fiber optics for time-bin based quantum information processing]]></title>
        <pubdate>2025-04-11T00:00:00Z</pubdate>
        <category>Review</category>
        <author>Nicola Montaut</author><author>Agnes George</author><author>Monika Monika</author><author>Farzam Nosrati</author><author>Hao Yu</author><author>Stefania Sciara</author><author>Benjamin Crockett</author><author>Ulf Peschel</author><author>Zhiming Wang</author><author>Rosario Lo Franco</author><author>Mario Chemnitz</author><author>William J. Munro</author><author>David J. Moss</author><author>José Azaña</author><author>Roberto Morandotti</author>
        <description><![CDATA[The development of integrated photonic systems, both on-chip and fiber-based, has transformed quantum photonics by replacing bulky, fragile free-space optical setups with compact, efficient, and robust circuits. Photonic platforms incorporating fiber-connected sources of correlated and entangled photon pairs offer practical advantages, such as operation at room temperature, efficient integration with telecom infrastructure, and compatibility with mature and efficient semiconductor fabrication processes for cost-effective and large-scale optical circuits. The stability and scalability of integrated quantum photonics platforms have facilitated the generation and processing of quantum information in the temporal domain within a single spatial mode. Time-bin encoded states, known for their robustness against decoherence and compatibility with existing fiber-optic infrastructure, have shown to be an efficient paradigm for advanced applications like quantum secure communication, information processing, spectroscopy, imaging, and sensing. This review examines recent advancements in fiber- and chip-based platforms for generating non-classical states and their applications as quantum state processors in the time domain. We discuss the generation of pulsed quantum frequency combs using microring resonators and intra-cavity mode-locked laser schemes, enabling co- and cross-polarized quantum photonic states. Additionally, the versatility of these resonator chips for entanglement generation is emphasized, including two- and multi-photon time-bin entangled schemes. We highlight the development of time-bin entanglement analyzers in fiber architectures, featuring ultrahigh stability and post-selection-free capabilities, which enable precise and efficient characterization of two- and higher-dimensional time-bin entanglement. We also review scalable on-chip schemes for quantum key distribution, demonstrating low quantum bit error rates and compatibility with higher-dimensional quantum communication protocols. Further, methods for enhancing temporal resolution in detection schemes, crucial for time-bin encoding, are presented, such as the time-stretch sampling technique using electro-optic modulation. These innovations, relying on readily available, telecom-based fiber-optic components, provide practical, scalable, and cost-effective solutions for advancing quantum photonic technologies. Looking forward, time-bin encoding is expected to play a pivotal role in the advancement of quantum repeaters, distributed quantum networks, and hybrid light-matter systems, advancing the realization of globally scalable quantum technologies.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2024.1501208</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2024.1501208</link>
        <title><![CDATA[Pruning and optimization of optical neural network as a binary optical trigger]]></title>
        <pubdate>2025-01-07T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Bokun Zhao</author><author>Xuening Dong</author><author>Kaveh Rahbardar Mojaver</author><author>Brett H. Meyer</author><author>Odile Liboiron-Ladouceur</author>
        <description><![CDATA[Optical neural networks implemented with Mach-Zehnder Interferometer (MZI) arrays are a promising solution to enable fast and energy-efficient machine learning inference, yet finding a practical application has proven challenging due to sensitivity to thermal noise and loss. To leverage the distinct advantages of integrated optical processors while avoiding its shortcomings given the current state of optical computing, we propose the binary optical trigger as a promising field of application. Implementable as small-scale application-specific circuitry on edge devices, the binary trigger runs binary classification tasks and output binary signals to decide if a subsequent energy intensive system should activate. Motivated by the limited task complexity, constrained area and power budgets of binary triggers, we perform 1) systematic, application-specific hardware pruning by physically removing specific MZIs, and 2) application-specific optimizations in the form of false negative reduction and weight quantization, as well as 3) sensitivity studies capturing the effect of imperfections in real optical components. The result is a customized MZI-mesh topology, MiniBokun Mesh, whose structure provides adequate performance and robustness for a targeted task complexity. We demonstrate in simulation that the pruning methodology achieves at least 50% less MZI usage compared to Clements and Reck meshes with the same input size, translating to at least between 4.6% and 24.2% savings in power consumption and a 40% reduction in physical circuitry footprint compared to other proposed unitary MZI topologies, sacrificing only 1%–2% drop in inference accuracy.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2024.1510954</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2024.1510954</link>
        <title><![CDATA[High-radiance phosphor-converted light sources for fluorescence analysis]]></title>
        <pubdate>2024-12-05T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Jan Müller</author><author>Ingo B. Ramsteiner</author><author>Reinhold Fieß</author><author>Cornelius Neumann</author>
        <description><![CDATA[Introduction/PurposeLaser-excited remote phosphor (LERP) light sources have gained significant importance in lighting and display applications due to their unique brightness and color-rendering qualities. In addition to their well-known advantages in these areas, we found that they also offer largely unexplored potential for sensor applications, such as quantitative fluorescence analysis. This potential is especially relevant when sophisticated optics operating under space and cost constraints require low-etendue sources with highly stable spectral properties. In this paper, we present an example of such an application. The purpose of our research is to assess currently available phosphor materials and design a light source to our particular reference application.MethodsFor this purpose, a characterization setup was developed that compares different phosphors excited by small laser spots, with diameters between 100 μm and 280 μm, in terms of emitted spectral radiance, incident laser power, and irradiance.ResultsThe investigation identified two suitable phosphors, including a phosphor that addresses the gap in the blue and green wavelength ranges. Furthermore, the importance of small laser spots was demonstrated, which allows reducing the laser power to simplify light source design and reduce costs.Discussion/ConclusionThis research proposes a functional set of phosphors for the abovementioned application and, at the same time, presents the current limitations of LERP light sources. We remain confident in the described application field for LERP sources and hope that the needs elaborated in this work will inspire further research and development of novel phosphor materials.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2024.1471239</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2024.1471239</link>
        <title><![CDATA[Multi-task photonic reservoir computing: wavelength division multiplexing for parallel computing with a silicon microring resonator]]></title>
        <pubdate>2024-10-23T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Bernard J. Giron Castro</author><author>Christophe Peucheret</author><author>Darko Zibar</author><author>Francesco Da Ros</author>
        <description><![CDATA[Nowadays, as the ever-increasing demand for more powerful computing resources continues, alternative advanced computing paradigms are under extensive investigation. Significant effort has been made to deviate from conventional Von Neumann architectures. In-memory computing has emerged in the field of electronics as a possible solution to the infamous bottleneck between memory and computing processors, which reduces the effective throughput of data. In photonics, novel schemes attempt to collocate the computing processor and memory in a single device. Photonics offers the flexibility of multiplexing streams of data not only spatially and in time, but also in frequency or, equivalently, in wavelength, which makes it highly suitable for parallel computing. Here, we numerically show the use of time and wavelength division multiplexing (WDM) to solve four independent tasks at the same time in a single photonic chip, serving as a proof of concept for our proposal. The system is a time-delay reservoir computing (TDRC) based on a microring resonator (MRR). The addressed tasks cover different applications: Time-series prediction, waveform signal classification, wireless channel equalization, and radar signal prediction. The system is also tested for simultaneous computing of up to 10 instances of the same task, exhibiting excellent performance. The footprint of the system is reduced by using time-division multiplexing of the nodes that act as the neurons of the studied neural network scheme. WDM is used for the parallelization of wavelength channels, each addressing a single task. By adjusting the input power and frequency of each optical channel, we can achieve levels of performance for each of the tasks that are comparable to those quoted in state-of-the-art reports focusing on single-task operation. We also quantify the memory capacity and nonlinearity of each parallelized RC and relate these properties to the performance of each task. Finally, we provide insight into the impact of the feedback mechanism on the performance of the system.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2023.1261267</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2023.1261267</link>
        <title><![CDATA[Investigation of laser-induced contamination on dielectric thin films in MHz sub-ps regime]]></title>
        <pubdate>2024-01-04T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Marek Stehlik</author><author>Janis Zideluns</author><author>Camille Petite</author><author>Valentin Allard</author><author>Marco Minissale</author><author>Antonin Moreau</author><author>Aude Lereu</author><author>Fabien Lemarchand</author><author>Frank Wagner</author><author>Julien Lumeau</author><author>Laurent Gallais</author>
        <description><![CDATA[High-repetition rate diode-pumped sub-ps lasers are widely used in the industrial sector for high-quality material processing applications. However, for their reliable operation, it is crucial to study the power handling capabilities of the optical components used in these systems. The optical components, such as mirrors, gratings, dichroic filters, and gain media, are designed based on dielectric thin films. When subjected to high-intensity laser radiation, the phenomenon of laser-induced contamination (LIC) can lead to the growth of a nanometric, highly absorbent layer on an irradiated optical surface, which can result in transmission or reflection loss and eventual permanent damage. In this study, we investigate LIC growth on dielectric oxide thin films in an air environment irradiated by MHz sub-ps laser at 515 nm. We examine the effect of thin film deposition method, material, and thickness on LIC growth dynamics. The irradiated spots on the surface are inspected using multiple observation methods, including white light interference microscopy and fluorescence imaging. Our results show that the LIC growth dynamics depend on the laser intensity and irradiation time and can be affected by the thin film deposition method, material, and thickness. These findings could be used to inform the development of more resistant optical components, ensuring long-term reliable laser operation required for industrial applications. The study highlights the need for validating optical components using tests that closely mimic real-world applications and provides insight into the complex processes that lead to LIC.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2023.1237132</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2023.1237132</link>
        <title><![CDATA[Light along curves: photonic shaping tools]]></title>
        <pubdate>2023-07-26T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Daniel Flamm</author><author>Julian Hellstern</author><author>Myriam Kaiser</author><author>Max Kahmann</author><author>Jonas Kleiner</author><author>Christoph Tillkorn</author>
        <description><![CDATA[A structured light concept is reported enabling to distribute a large number of focus copies at arbitrary positions in a working volume. Applying this holographic 3D-beam splitter concept to ultrashort laser pulses allows to deposit energy along accelerating trajectories in the volume of transparent materials. Based on the entirety of the volume modifications created in this way, the material can be separated, for example, to create chamfered glass edges. These photonic tools impress with enormous versatility, which enable equally diverse application strategies ranging from cutting and welding to data storing.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/aot.2023.1237679</guid>
        <link>https://www.frontiersin.org/articles/10.3389/aot.2023.1237679</link>
        <title><![CDATA[Three-dimensional femtosecond laser inscription of type a-based high-efficiency first-order waveguide Bragg gratings]]></title>
        <pubdate>2023-07-25T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Romain Laberdesque</author><author>Laura Loi</author><author>Théo Guérineau</author><author>Alain Abou Khalil</author><author>Sylvain Danto</author><author>Thierry Cardinal</author><author>Lionel Canioni</author><author>Yannick Petit</author>
        <description><![CDATA[A novel type of waveguide Bragg grating (WBG) is demonstrated based on femtosecond laser-induced Type A refractive index modifications, namely based of the photochemistry of silver species in a specialty ortho-phosphate glass matrix. First-order WBGs are reported in the near-infrared and down to 736 nm in the visible. Relative transmission measurements with a 500 µm long WBGs lead to narrow-bandwidth attenuations (sub-nm spectral FWHM) from 2.29 dB to 6.25 dB for periods from 240 nm to 280 nm, respectively. The corresponding estimated backward coupling coefficients show high values from 1.66 mm-1 up to 2.69 mm-1. Additionally, we report on a true 3D helix-shaped WBG that shows an even stronger relative attenuation of 10.3 dB for a 500 µm long WBG, equivalently corresponding to a backward coupling coefficient of 3.7 mm-1. These novel results pave the way for new silver-based laser-inscribed integrated photonic devices, among which the combination of Bragg gratings to form active/passive optical resonators, but also the direct inscription of WBG at the glass interface for enhanced sensing applications.]]></description>
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