PHOTOPTICS 2026 Abstracts

Area 1 - Lasers
Full Papers Short Papers
Area 2 - Optics
Full Papers Short Papers
Area 3 - Photonics
Full Papers Short Papers

Area 1 - Lasers

Full Papers
Paper Nr: 17
Title:

Experimental Investigation of Surface Topography Evolution During Laser Remelting Using Statistical Amplitude Distribution Analysis
Authors:

Evgueni V. Bordatchev, Srdjan J. Cvijanovic and Remus O. Tutunea-Fatan
Abstract: Surface finish is a critical quality factor in fabricated components. Surface polishing by laser remelting (SP-LRM) is an advanced technique that improves surface quality by melting and redistributing a thin surface layer without altering the overall structural form. This paper introduces a statistical digital twin of the LRM process and demonstrates the applicability of statistical amplitude distribution characteristics for analysing surface topography evolution. The thermodynamic transformation of the initial surface is examined using cybernetic and machine learning approaches, addressing two key LRM components: the remelting and resolidification of both the bulk material and the surface topography. LRM experiments were performed on flat and ground surfaces of H13 tool steel samples using laser powers of 25 W and 100 W. The resulting topographies were characterized by roughness average, averaged transverse (W-shape) profile, transverse roughness profile, and probability density function. Redistribution of molten material, along with surface quality changes, was comparatively analysed. Results show that the relative contribution of bulk versus surface topography transformation strongly depends on laser power. At low power (e.g., 25 W), surface quality is dominated by transformation of the initial topography, enabling statistically reliable modelling and digital identification. Statistical amplitude distribution analysis thus provides deeper insight into molten material redistribution and advances the scientific foundation of LRM technology.
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Short Papers
Paper Nr: 25
Title:

Periodicity Control of Laser-Induced Periodic Surface Structures through a Thin Film on Si Substrate
Authors:

Reina Miyagawa, Takahito Inoue, Hiyori Uehara and Ali Rezvani
Abstract: Ultrashort-pulse laser processing enables precise microfabrication with minimal thermal damage. In this study, we investigated the period control of laser-induced periodic surface structure (LIPSS) on Si substrates by introducing thin oxide films. Al₂O₃ and TiO₂ films with thicknesses of 30–200 nm were deposited by atomic layer deposition, and femtosecond laser irradiation was performed under various pulse numbers (N = 18–1000) and powers (50–300 mW). The results show that the LIPSS period decreases with increasing film thickness for both Al₂O₃ and TiO₂ films, while the influence of laser power on the period is relatively small. For example, the LSFL period decreased from 797 nm to 712 nm through a 200 nm TiO₂ film at 300 mW (N = 100). These findings suggest that the dissimilar thin films affect the LIPSS period, offering a pathway to more controllable periodic nanostructures.
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Paper Nr: 53
Title:

Comparison of Heat Dissipation Characteristics between Edge-Emitting and Surface-Emitting QCLs
Authors:

Shigeyuki Takagi, Hirotaka Tanimura, Tsutomu Kakuno, Rei Hashimoto, Kei Kaneko and Shinji Saito
Abstract: The thermal resistance of edge-emitting and surface-emitting Quantum cascade lasers (QCLs) was evaluated using 3D thermal flow analysis and measurements of static method. Edge-emitting QCLs excite laser light in a narrow ridge region on the order of 10 µm, while surface-emitting QCLs excite laser light in a mesa region on the order of mm. 3D simulation results indicated that the total thermal resistances of the QCL device were 13.3 W/K for the edge-emitting QCL and 8.2 W/K for the surface-emitting QCL, respectively. On other hand, measurement results showed values of 12.0 K/W for the edge-emitting QCL and 8.5 K/W for the surface-emitting QCL. The simulation results were in good agreement with measurement results for both device structures. Based on these results, a surface-emitting QCL equipped with a photonic crystal was fabricated and a laser output of 1.1 W was obtained.
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Area 2 - Optics

Full Papers
Paper Nr: 22
Title:

Evaluation of Injection Molding Conditions for Resin Molds Using Reflective Wavefront Sensor
Authors:

Kazumasa Tatsumi, Kentaro Saeki, Shin Kubota, Yoshikatsu Kaneda, Kenji Uno, Kazuhiko Ohnuma and Tatsuo Shiina
Abstract: Injection molding technology has seen remarkable advancements in recent years. With the development of precision molding, it has become possible to reproduce complex and fine geometries, leading to increased demand in applications such as optical lenses and medical devices. In the field of contact lens (CL) manufacturing, a method known as a double-sided molding method is commonly used, in which a pair of resin molds-male and female-replicating the front and back surface designs are employed to form the lens. The creation of highly precise resin molds that match the design specifications is essential for successful lens formation, making injection molding a critical factor. This study aims to evaluate the impact of injection molding conditions and mold design on the quality of resin molds by developing a reflective wavefront sensor specifically designed for mold measurement. The system enabled the evaluation of micrometer-scale deviations and shrinkage caused by differences in design and molding parameters with Zernike coefficients. The proposed method demonstrated sufficient measurement efficiency for evaluating resin molds in CL production. Furthermore, this approach has broad applicability, including feedback for optimizing molding conditions, quality control in lens manufacturing, and assessment of replication accuracy in mold fabrication.
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Paper Nr: 23
Title:

Linking Air Pollution to Internal Plant Responses Using a GLCM Texture Analysis of OCT Images under Ozone Stress
Authors:

Hayate Goto and Tatsuo Shiina
Abstract: Comprehensive monitoring of air pollution provides valuable insights for improving crop quality and yield. In urban areas, ozone, the main component of photochemical oxidants, can reach high concentrations due to dense traffic networks, requiring effective countermeasures. This study focuses on indicator plants, which reflect environmental stress through their own physiological responses. Using non-destructive, non-contact Optical Coherence Tomography (OCT) for plant, we measured white clover leaves(indicator plant for ozone) exposed to two ozone concentrations in an incubator. Traditional metrics such as palisade tissue thickness and strength showed changes with ozone exposure, but these two parameters alone are not enough to distinguish the various stress effects. The purpose of this study is to explore an alternative analytical approach by applying the Gray Level Co-occurrence Matrix GLCM) as texture analysis to OCT images. This method enables quantification of internal structural changes from multiple perspectives. Results showed that tissue thickness increased and strength decreased with ozone damage. GLCM contrast values tended to decrease under low ozone and increase under high ozone. These findings suggest that texture analysis provides complementary structural information beyond conventional metrics, enabling accurate evaluation and differentiation of ozone stress in plants.
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Paper Nr: 49
Title:

Optimization of Solar Furnace Performance in Parkent (Uzbekistan): Analysis of Heliostats Locations Based on Laser Scanning
Authors:

Shakhzod Takhirov, Sultan Kudratov, Akbar Normo‘minov, Odilkhuja Parpiev, Zhavohir Shermatov and Ravshan Shamansurov
Abstract: The paper presents the results of the analysis of the laser scanning project conducted on the site of the solar furnace in Parkent (Uzbekistan). This solar furnace consists of a main parabolic reflector and 62 heliostats that reflect sunlight onto it. The laser scanning was conducted with a terrestrial laser scanner, enabling the generation of a precise digital 3D model of this unique object. As a result, the current locations of all heliostats relative to the main reflector were determined with high accuracy. These locations may differ from the design-prescribed locations due to construction tolerances and/or soil settlement under each heliostat. All these imperfections can negatively affect the furnace's performance. To study the effect of these imperfections, as an example, the last five heliostats of the array are selected. This paper focuses on these heliostats and evaluates their performance based on their current location and orientation.
Short Papers
Paper Nr: 12
Title:

Photonic Continuity: Sustainable Wired and Wireless Photonics from Kilobits per Second (Kbps) to Petabits per Second (Pbps)
Authors:

Olivier Bouchet, Yanes Yahoui, Guillaume Vercasson, Vincent de la Broise, Irene Kolokytha and Sokratis Barmpounakis
Abstract: Optical wireless communication has been present for more than half a century, from home remote control to data laser link between satellites, without mentioning the military applications which have clearly understood this technology’s potential. The paper presents a general view of this field, including fiber optic development up to passive optical network, and then focuses on the latest addition in this area - Fiber Wireless (FiWi) offering a very high-speed wireless solution and the opportunity of a sustainable all-optical network (AON).
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Paper Nr: 52
Title:

Different Regimes of Plasma Self-Organization under the Subpicosecond Laser Pulse Exposure: The Role of Avalanche
Authors:

Anna V. Bogatskaya, Ekaterina A. Volkova, Maria P. Verteletskaya and Alexander M. Popov
Abstract: In this study we perform 3D self-consistent numerical simulations of a focused laser pulse exposure in the bulk of fused silica. The model combines the second-order wave equation in the cylindrical frame with a rate equation for the density of charge carriers in the conduction band. We examine the effect of avalanche ionization and the role of reflective coatings on the laser plasma self-organization. We show that by using reflecting coatings one can manage the complex pattern of laser field distribution in the focal area thereby controlling the profiles of plasma microstructures.
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Paper Nr: 63
Title:

OCT Characterization and Spectral Chlorophyll Index Measurement of Plant Leaves During Senescence
Authors:

Jumar Cadondon, Hayate Goto, Seiroh Okaneya and Tatsuo Shiina
Abstract: Leaf senescence involves progressive structural and biochemical changes that are difficult to quantify using traditional, destructive techniques. This study explores the combined use of Optical Coherence Tomography (OCT) characterization and spectral chlorophyll index (SCI) measurement to non-invasively monitor leaf microstructural and pigment alterations throughout the senescence process. OCT imaging was employed to assess changes in leaf internal architecture, including layer thickness, mesophyll integrity, and scattering patterns. SCI values were obtained through reflectance-based spectral analysis and fluorescence spectroscopic methods to estimate chlorophyll degradation with enhanced sensitivity. Results showed a consistent decline in SCI values corresponding with OCT-detected structural deterioration, such as reduced tissue cohesion and increased scattering heterogeneity. Strong correlations between OCT parameters and chlorophyll index trends indicate that microstructural breakdown closely parallels pigment loss during aging. The integration of OCT imaging with spectral and fluorescence-based chlorophyll metrics offers a robust, real-time, and non-destructive approach for evaluating leaf senescence, with potential applications in plant physiology research, crop monitoring, and precision agriculture.
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Paper Nr: 47
Title:

Visible Light Communication System Using Short Fluorescent Plastic Optical Fibers as Omnidirectional Antennas
Authors:

Bettina Fanzeres Cordoniz Buckingham Maia, José Roberto Moraes de Andrade, Patrick Couceiro Frizzini Vieira, Ivan Landerson das Chagas Pinheiro, Ricardo Marques Ribeiro and Alexandre Castro de Toledo Santos
Abstract: This paper presents the development and experimental evaluation of a visible light communication (VLC) system employing digital NRZ-OOK modulation and a low-cost micro-controlled platform (Arduino Uno). The receiver architecture is based on fluorescent plastic optical fibers (FPOFs) operating as omnidirectional optical antennas. This study focuses on evaluating the capabilities and limitations of FPOFs for low-frequency optical transmission in short-range applications. Experimental results confirm the feasibility of the “fluorescent optical antenna” concept, achieving 100% data integrity (BER < 10⁻⁵) in a perpendicular configuration (90° relative the line-of-sight), a condition under which conventional VLC systems typically fail. Four commercially available FPOFs (named IFO Red, R-3, O-2, and Y-11) were characterized, showing comparable performance after applying an adaptative threshold scheme to stabilize the detection process, achieving a data rate of 24.35 bytes/s. The findings validate the use of FPOFs as efficient angular converters for robust short-range optical communication and highlight their potential for low-cost and low-data rate VLC receiver systems.
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Area 3 - Photonics

Full Papers
Paper Nr: 61
Title:

Buried Graphene: Unlocking High-Performance on-Chip Near-Infrared Photodetection
Authors:

Teresa Crisci, Luigi Moretti, Mariano Gioffrè, Mario Iodice, Giuseppe Coppola, Babak Hashemi, Mohammed Mammeri, Francesco Giuseppe Della Corte and Maurizio Casalino
Abstract: This work introduces a monolithically integrated photodetector incorporating graphene and tailored for near-infrared wavelengths around 1.55 µm. The device relies on a multilayer waveguiding platform formed by crystalline silicon combined with hydrogenated amorphous silicon and an embedded graphene sheet. Locating graphene inside the optical guiding region strengthens the coupling between the propagating mode and localized states at the graphene–amorphous silicon boundary. Under optical excitation, these states inject carriers into graphene, leading to a modulation of the thermally assisted current across the graphene–silicon Schottky interface. This detection mechanism has been named SPARK. A CMOS-compatible fabrication flow has been implemented to ensure scalability while maintaining graphene quality, as verified by Raman characterization. The photodetector achieves a peak responsivity of 1.9 A/W at 1535 nm, yielding an external quantum efficiency exceeding unity (153%) and a noise equivalent power of 113 fW/Hz¹ᐟ². The proposed process avoids the need for deep-submicron patterning, offering significant fabrication tolerance. Furthermore, the responsivity increases as the optical input power decreases, highlighting the suitability of this device for low-power optical sensing and monitoring within integrated photonic platforms.
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Short Papers
Paper Nr: 16
Title:

Design and Evaluation of Real-Time Signal Processing in a Long-Range Distributed Acoustic Sensing (DAS) Using CloudSim
Authors:

Abdusomad M. Nur, Yalemzewd Negash Shiferaw and Yonas Muanenda
Abstract: The processing of raw traces in a long-distance Distributed Acoustic Sensing (DAS) for real-time monitoring requires the careful design of computational resources to guarantee requisite dynamic performance. In this work, we will focus on the design of a system for the performance evaluation of cloud computing systems for diverse computations on long-range DAS spanning up to a distance of 110-km with meter-scale spatial sampling and resolution employing the CloudSim framework. The results reflect that, although a larger number of computations is required as the fiber length increases, the overall speed of computation achieved with a particular configuration of Virtual Machines (VMs)is still suitable for continuous real-time monitoring. In addition, the impact of the VM parameters on computation time is explored, highlighting the importance of resource optimization in the design of the computations in a long-range DAS system for efficient performance. The study also observes a notable trend of lower processing time overhead for additional samples per trace, showing the scalability of the cloud-based processing of data in a DAS when the length of the fiber increases.
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Paper Nr: 15
Title:

Moving Bragg Solitons in a Semilinear Grating-Assisted Coupler with Cubic-Quintic Nonlinearity and Phase Mismatch
Authors:

Etu Podder and Javid Atai
Abstract: We investigate the dynamics of moving Bragg solitons in a semilinear grating-assisted coupler, in which one core exhibits cubic-quintic nonlinearity while the other is linear, with a phase mismatch between the gratings. The linear spectrum of the system was analyzed to identify the existence range of solitons. Moving soliton solutions were then determined using systematic numerical methods. Due to the presence of fifth-order nonlinearity in the system, two distinct and disjoint families of moving Bragg solitons – referred to as Type 1 and Type 2 – are found within the central bandgap. We conducted a stability analysis for both types of solitons to evaluate the stabilizing effects of soliton velocity, phase mismatch, and other system parameters. Our results indicate that increasing the phase shift, leads to the stabilization of both Type 1 and Type 2 moving solitons.
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Paper Nr: 55
Title:

Design and Optimization of a Compact, Broadband, Polarization-Independent, and Low-Loss Y-Junction Optical Adiabatic Switch
Authors:

Mohamed Mammeri, Maurizio Casalino, Teresa Crisci, Lakhdar Dehimi and Francesco G. Della Corte
Abstract: Optical switches are fundamental building blocks for signal routing in photonic integrated circuits (PICs). Among the various switching architectures, Y-junction adiabatic switches are considered promising candidates due to their broadband operation range and polarization-independent property. However, the adiabatic switch typically requires a long coupling length to satisfy the adiabaticity criteria, which leads to a large device footprint. In this work, we applied a monotonic optimization approach to systematically reduce the length of the adiabatic tapered waveguide used in the adiabatic switches. This approach relies on identifying the regions of low and high phase matching between the tapered waveguides through overlap analysis, which allows for controlling the adiabaticity angle more efficiently resulting in a significantly shorter device. Lumerical Finite-Difference Eigenmode (FDE) solver was used to calculate the modes overlap, while the device performance was evaluated using Eigenmode Expansion (EME). The results show a significant reduction of the tapered waveguides length by approximately 38% compared to the reference device, while simultaneously improving the switching performance of the device. The device was evaluated over a broadband wavelength range of 1500–1600 nm. The optimized switch achieved an extinction ratio of 33.8 dB and 43.73 dB for the TE mode at wavelength of 1500 nm and 1600 nm respectively. While in TM mode the ER obtained are 20.5 dB and 24.83 dB for the same wavelengths. These results unveil the effectiveness of the proposed optimization approach for realizing compact, high-performance adiabatic optical switches suitable for integrated photonic platforms.
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