PHOTOPTICS 2025 Abstracts

Area 1 - Lasers

Short Papers

Paper Nr:	22
Title:	Slice Reconciliation in Continuous-Variable Quantum Key Distribution Using Discrete Modulation
Authors:	Margarida Almeida, Armando N. Pinto and Nuno A. Silva
Abstract:	Information reconciliation is a critical component of Continuous-Variable Quantum Key Distribution (CV-QKD) systems. This particular step of the CV-QKD system significantly affects the extraction key rate. Previous studies that incorporate higher-order discrete modulation (DM) while accounting for the information reconciliation step in the computation of the extraction key rate of CV-QKD systems have focused on multidimensional reconciliation. However, higher-order DM formats, such as 64-Quadrature Amplitude Modulation (QAM), enable higher signal-to-noise ratios (SNRs) where slice reconciliation is known to outperform multidimensional reconciliation. In this work, we compare the performance of multidimensional reconciliation and slice reconciliation in DM-CV-QKD systems. Our findings demonstrate that slice reconciliation delivers superior performance at metropolitan distances. At 20 km, using slice reconciliation with 3 slices of code rates 0, 0.01, and 0.6 increases the key rate by more than 400 times when compared to multidimensional reconciliation with a code rate of 0.05. This significant performance boost more than compensates for the higher computational time associated with slice reconciliation. With the proper optimization of the number of slices, and of the code rate per slice, slice reconciliation is a valid option for real-world implementations of DM-CV-QKD systems using higher-order constellations.
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Area 2 - Optics

Full Papers

Paper Nr:	28
Title:	Evaluation of Resin Molds Change in Design and Polymerization by Using a Wavefront Sensor
Authors:	Kazumasa Tatsumi, Kentaro Saeki, Shin Kubota, Yoshikatsu Kaneda, Kenji Uno, Kazuhiko Ohnuma and Tatsuo Shiina
Abstract:	Advances in molding technology have made it possible to produce plastic molded products with complex shapes. In contact lens manufacturing, a double-sided molding method using resin molds is employed, where the front and back designs are replicated through injection molding. However, shape changes in the resin molds caused by heat treatment (polymerization) during the manufacturing process affect lens characteristics. This study proposes a method using optical techniques to clarify the influence of mold design and polymerization on resin mold shapes. Five types of resin molds were measured using a wavefront sensor, which allows for high-accuracy, non-contact measurement. Wavefront aberrations and radii of curvature were evaluated, and results showed that polymerization caused slight deviations from the design values and changes in shrinkage rates. This method demonstrated its effectiveness in measuring and evaluating resin molds for contact lens production. Furthermore, the proposed method has wide-ranging applications, including quality control in lens manufacturing and evaluating the transfer accuracy of metal molds.
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Paper Nr:	29
Title:	OCT Image Inspections of Indicator Plant Leaves Under Environmental Stresses
Authors:	Hayate Goto and Tatsuo Shiina
Abstract:	In recent years, environmental pollution has intensified, raising concerns about the health impacts on humans and plants. In this study, we evaluate the indicator plants that can indicate environmental conditions by Optical Coherence Tomography (OCT) which can make tomographic images quantitatively and non-invasively observation. Trifolium repens, commonly known as white clover, which is prevalent in Japan, serves as an indicator plant for ozone, suggesting that OCT measurements of Trifolium repens enabled the estimation of ozone concentration. However, to evaluate whether the changes observed inside leaves are specific to ozone, it is necessary to also differentiate other environmental stresses. In this study, we compared the OCT measurement results of Trifolium repens grown under ozone stress and water stress. The analysis focused on variations in tissue thickness, interference light intensity, and texture of the OCT images, while also considering the stability of the analytical parameters. Differences were observed in the trends of changes in palisade tissue thickness and interference light intensity under ozone stress and water stress. Although variations under those stresses were observed in the results of texture analysis, these were not as significant as those in thickness and intensity. This result indicates that plants induce specific changes within their leaves due to different stresses, confirming the potential of OCT measurements for environmental assessments.
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Paper Nr:	34
Title:	Independent Real and Imaginary Spectral Analysis for Improving the Brillouin Frequency Shift Resolution in the Differential Cross-Spectrum BOTDR (DCS-BOTDR) Fiber Sensor
Authors:	Ain Nabihah Mohammad Rihan, Mohd Saiful Dzulkefly Zan, Yosuke Tanaka, Mohd Hadri Hafiz Mokhtar, Norhana Arsad and Ahmad Ashrif A. Bakar
Abstract:	We propose a technique to improve Brillouin gain spectrum (BGS) acquisition in a Brillouin optical time domain reflectometry (BOTDR) fiber sensor by independently analyzing the real and imaginary components of the Brillouin backscattered signal through fast Fourier transform (FFT) analysis. This technique aims to enhance Brillouin frequency shift (BFS) resolution in our previously proposed differential cross-spectrum BOTDR (DCS-BOTDR) method. Using an intensity modulation scheme to generate a probe pulse pair, we conducted temperature sensing experiment by heating an 8 m section at the far end of a 1.2 km fiber at 70°C. The experimental results showed a significant reduction of BGS width from 128 MHz to around 53 MHz with the real spectrum component. Consequently, this has resulted in the enhancement of the BFS resolution to 1.49 MHz using the real spectrum and 1.51 MHz with the imaginary spectrum. We have also achieved 40 cm spatial resolution measurement and reduced the processing time from 7.21 s to 7.08 s, demonstrating an improved efficiency and accuracy for distributed temperature measurement in BOTDR sensor.
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Paper Nr:	35
Title:	Analysis of the Influence of Atmospheric Turbulence on Laser Wireless Power Transmission
Authors:	Guan Huang, Chao Geng and Xinyang Li
Abstract:	Laser Wireless Power Transmission (LWPT) technology has significant applications in many fields, such as emergency rescue, remote power supply for aircraft, and space solar power stations. As the beam transmission distance increases, the effects of atmospheric turbulence become significant. However, this issue has not yet been specifically discussed. In this paper, theoretical analysis and numerical simulation experiments are carried out to study the effect of atmospheric turbulence on the performance of LWPT. The results show that the power transmission efficiency of LWPT is determined jointly by the mean and uniformity of the beam intensity. Under the influence of moderate atmospheric turbulence (with C2n of 8.6×10−16m−2/3), the maximum power of the photovoltaic array will be seriously affected (from 100% to less than 0.5%), and simply compensating for the tilt aberration will not make a significant difference. The conclusion of this paper shows the importance of adaptive optics (AO) systems in future long-range LWPT links.
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Paper Nr:	39
Title:	Phase Combining Strategies for Polarization-Independent Demodulation in a DAS Using Homodyne Detection with Delayed Self-Mixing in a Non-Stabilized Mach-Zehnder Interferometer
Authors:	Almaz Demise, Fabrizio Di Pasquale and Yonas Muanenda
Abstract:	We investigate a suitable polarization diversity algorithm for mitigating polarization fading in phase demodulation in a φ-OTDR based on a delayed Mach-Zehnder interferometer (MZI) and a polarization-diversity 90-degree optical hybrid. The intermediate components of the signal are combined using four different strategies employing weighing factors calculated from the SNR of the in-phase component and visibility of backscattering amplitude in the slow and fast axes to suppress polarization fading in distributed dynamic phase measurements. We compare the algorithms in terms of suitability for suppressing fading and added computational times. The proposed technique uses a single compact amplifier at the source and employs delayed self-mixing in an unbalanced MZI, thereby relaxing the requirement of temperature and phase isolation in the receiver interferometer. Experimental results show that, while all combining strategies mitigate fading, the selection of higher SNR of the in-phase component at the far end yields the best results in terms of ease of computation and could accurately detect weak acoustic signals at the end of a 10-km sensing fiber with a frequency of 2 kHz in the presence of fading in a single polarization.
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Short Papers

Paper Nr:	25
Title:	Advancing Detector Shielding with Thermo-Optic Defocusing in PMMA Integrated on Silicon Nitride
Authors:	Soon Thor Lim, Thomas Ang, Zifeng Yuan, Thanh Xuan Hoang, Dewen Zhang, Ching Eng Png, Aaron Danner and Gandhi Alagappan
Abstract:	This study develops an on-chip optical power limiter (OPL) based on the thermo-optic defocusing effect in PolyMethyl-Methacrylate (PMMA) to protect an avalanche photodiode (APD) from high optical power damage. The OPL is designed to operate within a reduced power range of 0.1 mW to 10 mW by adjusting waveguide dimensions, taper widths, and free-space region (FSR) lengths. Detailed calculations, modelling, and simulations are presented, demonstrating the efficacy of the OPL in limiting optical power reaching the APD, preventing damage and ensuring stable performance in high-power applications.
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Paper Nr:	30
Title:	Early Dental Caries and Demineralization Measurements by Using Portable OCT Scanner
Authors:	Serioh Okaneya and Tatsuo Shiina
Abstract:	There is an increasing need in dental research and clinical practice for accurate measurements of teeth. Currently, methods such as x-rays and quantitative light-induced fluorescence (QLF) are used, but there are problems such as the effects of radiation and limitations in resolution. Optical Coherence Tomography (OCT) used in this study uses near-infrared light, which has no effect on the human body and provides very high resolution in the range of tens of micrometers. OCT allows for non-invasive imaging, making it safer for repeated use and ideal for monitoring caries progression over time. In this study, we developed a portable OCT scanner specialized for dental use and measured and evaluated early caries and demineralization.
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Paper Nr:	31
Title:	Broadband Infrared Imaging for Enhanced Gas Leak Detection
Authors:	Jianzhi Fan, Jing Zhou, Qi Zhao, Dong Luo and Wei Chen
Abstract:	This paper presents a passive broadband infrared imaging system designed for gas leak detection. The system utilizes an optical design optimized for the 3–14 µm range, including a wide-spectrum lens and an uncooled infrared camera. The broadband capability enables the detection of various gases across a wide spectral range. To identify gas leaks, a novel adaptive gas leakage detection algorithm based on YOLOX and traditional image processing techniques is developed. The system’s performance is validated through field experiments with SF6 and CO2 gases, showcasing its ability to accurately detect and segment gas leakage regions. Furthermore, the study investigates the potential for gas composition analysis using the system’s broadband imaging. Future work aims at optimizing the optical design and enhancing detection sensitivity for improved efficiency.
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Paper Nr:	43
Title:	Microstructure, Extinction Coefficient, and Chlorophyll Content of Philippine Bamboo Leaves by a Portable TD-OCT Scanner
Authors:	Jumar Cadondon, Edgar Vallar, Maria Cecilia Galvez and Tatsuo Shiina
Abstract:	Bamboo is one of the most utilized non-timber forest products in the Philippines. Common bamboo leaf infections are caused by sunlight, and nutrient deficiency. In this study, we have developed a portable time domain-optical coherence tomography (TD-OCT) to study in vivo leaf microstructure changes in Philippine bamboo (Bambusa spinosa). TD-OCT analysis shows unique features among different layers of the leaves specifically on the epidermis and palisade layers when the unhealthy part is compared to the healthy part. Extinction coefficient from the A-scan analysis showed significant difference from unhealthy part (1.03 ± 0.20 mm-1, N =12, p<0.05) and healthy part (0.72 ± 0.27 mm-1, N =12, p<0.05). In addition, RGB data was compared for both unhealthy and healthy part of the bamboo leaves. A red shift is observed from the unhealthy part of the leaves. It is also observed by a decrease of 60% in chlorophyll-a content of the unhealthy part as compared to the healthy part. Same inverse correlation is also observed when the extinction coefficient is compared with the chlorophyll content.
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Paper Nr:	45
Title:	The Role of Self-Focusing During the Laser Microstructuring in the Volume of Fused Silica
Authors:	Anna V. Bogatskaya, Ekaterina A. Volkova 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 cylindrical coordinates with a rate equation for the density of charge carriers in the conduction band. Our results indicate that a dense plasma formation near the focal plane effectively scatters and reflects the laser pulse. The coherent interference between the incident and scattered laser waves creates regions of intense field ionization, resulting in periodic plasma nanostructures along both the ρ- and z-axes. We also examine the impact of nonlinear refractive index effects, which lead to pulse self-focusing. We should note that similar subwavelength, divergent structures in material modification regions have been observed in recent experiments conducted under comparable laser focusing conditions.
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Paper Nr:	50
Title:	Light Communication Technology: An Enabling Technology for Sustainable Wired and Wireless Solutions
Authors:	D. Chiaroni, S. Leroux, M. Fleschen, B. Berde, F. Abdeldayem, N. Serafimovski, H. Nikol, N. Delaunay, B. Béchadergue, B. Azoulay, S. Cordette, S. Clement, J. Tabu, C. Lepers and H. Haas
Abstract:	Optical wired and wireless technologies are analysed in this paper to address sustainable solutions for vertical markets. After a description of the context, of the different technologies adopted, of use cases and their associated services, this paper demonstrates through a comparative analysis with a classical Ethernet LAN interconnecting Wi-Fi access points for a fixed network, that optical technologies in a heterogeneous context can provide key added value services in a sustainable way.
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Area 3 - Photonics

Full Papers

Paper Nr:	17
Title:	Design and Simulation of a Vertical Waveguide Based Polarization Color Routing Device
Authors:	F. Ali, B. Figeys, O. Shramkova, R. MacCiarnain, X. Rottenberg, R. Gehlhaar and J. Genoe
Abstract:	We present a high index vertical-waveguide based optical device which offers polarization and color routing with sub-micron spatial resolution over the visible spectrum (400-700 nm). The device exploits a polarization, color splitting principle to effectively separate orthogonal linear polarization states, colors of the incident light beam respectively. Finite difference time domain simulations are performed to optimize the design parameters and analyse the device performance under different illumination conditions. The unique ability to simultaneously manipulate polarization and color with remarkable efficiency can allow a new era for high-resolution optical imaging devices.
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Short Papers

Paper Nr:	14
Title:	Effect of Phase Mismatch on the Dynamics of Bragg Solitons in a Semilinear Coupled Bragg Grating System with Cubic-Quintic Nonlinearity
Authors:	Etu Podder and Javid Atai
Abstract:	We investigate the dynamics of quiescent Bragg solitons in a dual-core fiber Bragg grating system with a phase shift between the gratings where one core has cubic-quintic nonlinearity, and the other is a linear core. Since cubic-quintic nonlinearity is present in one core, our system demonstrates the existence of two distinct and disjoint families of quiescent Bragg solitons within the specified bandgap, classified as Type 1 and Type 2 solitons. Both types of quiescent solitons have been analyzed numerically to assess their stability. The stability analysis reveals that the presence of the phase mismatch between Bragg gratings enhances the overall stability for Type 1 solitons and leads to the formation of stable Type 2 solitons.
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Paper Nr:	18
Title:	MILI: Biophotonics Technology for In-Situ, Fast, Accurate and Cost-Effective Milk Analysis
Authors:	Panayiota Demosthenous, Maria Aspri, Maria Moyseos and Marios Sergides
Abstract:	Contaminated milk poses serious health risks to consumers, highlighting the need for efficient detection methods. Currently, the dairy industry relies on precise but time-consuming laboratory methods that require specialized personnel. The work presented here aims to address this by developing a fast, cost-effective and reliable system for detecting common contaminants in milk at the farm level. The MILI device is based on state-of-theart biophotonics, combining customised biosensors, optical analysis, electronics, and software modules. The detection method relies on the use of fluorometry, where the signal originating from labelled antibodies bound to specific analytes (antibiotics and toxins) is measured. Two different chromophore molecules suspended in buffer and milk solutions were used to test the detection capabilities of the device with excitation/emission wavelengths at 562 nm/584 nm and 650 nm/665 nm, respectively. We describe the different modules of the device and present a detailed experimental work performed to validate the device operation and extract performance parameters such as the limit of detection in terms of chromophore concentration, accuracy, sensitivity, and specificity. The obtained results demonstrate reliable detection of low chromophore concentrations (<100 pM), with repeatability and robustness confirmed under different conditions, making the MILI system an ideal candidate for rapid, cost-effective contamination detection device.
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Paper Nr:	19
Title:	Advancing Chloride Ion Detection in Edible Oils: Enhanced Sensitivity with NCQD/Ag Nanotriangles via Localized Surface Plasmon Resonance
Authors:	Muhammad Qayyum Othman, Mohd Hafiz Abu Bakar, Nur Hidayah Azeman, Nadhratun Naiim Mobarak and Ahmad Ashrif A. Bakar
Abstract:	Chloride ion detection in edible oil is crucial for food safety and preventing harmful compounds like 3-MCPD during refining. This study presents a novel method utilizing Nitrogen-Doped Carbon Quantum Dots (NCQDs) combined with Silver Nanotriangles (AgNTs) through Localized Surface Plasmon Resonance (LSPR) for chloride ion detection. The chemical properties of AgNT-NCQD enhance sensor performance by improving stability and biocompatibility while providing new binding sites for chloride ions. LSPR allows precise monitoring of the interaction between AgNT-NCQD and chloride ions, resulting in a distinct LSPR peak for accurate detection. The synergy between surface plasmon resonance and NCQDs increases sensitivity, with significant LSPR peak shifts upon chloride exposure. This technology offers a wider dynamic range and lower detection limits, demonstrating excellent selectivity for chloride ions in edible oil. The enhanced properties of NCQDs make this sensing platform vital for food quality assurance and consumer health protection.
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Paper Nr:	23
Title:	All-Fibre Comb Filter with Narrow Bandwidth Based on a Dual-Pass Mach-Zehnder Interferometer
Authors:	Li Wei
Abstract:	A theoretical analysis of an all-fibre comb filter with narrow bandwidth is presented, based on a dual-pass Mach-Zehnder interferometer (DP-MZI) with two variable ratio couplers. While the DP-MZI has previously been used to construct a flattop comb filter via the reflection port, in this work it is employed as a narrow bandwidth comb filter through the transmission port. Two conditions are newly derived to determine how to choose the coupling ratios to optimize the optical performance of the proposed comb filter. First, to obtain a lossless narrow-bandwidth filter, the coupling ratios of the two couplers must be equal. Second, to achieve maximum extinction ratio, these coupling ratios are equal to 0.146 or 0.854. The impact of the coupling ratios on bandwidth and extinction ratio is investigated. It is shown that the 3-dB bandwidth can be further reduced by tuning the coupler ratios near the optimal value. This unique property is highly desirable for applications in fibre lasers, optical sensing technology and reconfigurable optical systems.
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Paper Nr:	42
Title:	Millimeter Wave Imaging Using Up-Conversion Detection Method with Glow Discharge Detector and Photoreceiver Combination
Authors:	Arun Ramachandra Kurup, Daniel Rozban, Amir Abramovich, Yitzhak Yitzhaky and Natan Kopeika
Abstract:	This paper presents an advanced photonic detection system for high-resolution millimeter-wave (MMW) imaging, utilizing an up-conversion detection method with a Glow Discharge Detector (GDD) and a photoreceiver to capture detailed images of metallic objects. The system employs a 105 GHz MMW beam, generated by a custom transmitter, which illuminates the object. Reflected MMW radiation is collected by a large spherical mirror and directed to the GDD, where the MMW signal is up converted to an optical signal. The GDD’s response to MMW incidence produces a measurable increase in light intensity, detected by a low-noise photoreceiver equipped with a Si-PIN photodiode, enhancing the sensitivity and accuracy of the detection process. The GDD-photoreceiver assembly is mounted on motorized linear stages, enabling precise vertical and horizontal scanning in patterns, which facilitate the creation of grayscale MMW images. Data acquisition is conducted through a dedicated platform that translates the detected signals into clear, high-quality images. This system showcases significant advancements in photonic detection for MMW imaging, offering enhanced resolution and sensitivity, which are advantageous for a range of applications.
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Paper Nr:	49
Title:	Increasing Power Output of Quantum Cascade Lasers (QCLs) Added with AlAs/InAs Layers Through Bandgap Engineering
Authors:	Shigeyuki Takagi, Hirotaka Tanimura, Tsutomu Kakuno, Rei Hashimoto, Kei Kaneko and Shinji Saito
Abstract:	We applied bandgap engineering to n-type semiconductor quantum cascade lasers (QCLs) and investigated the effects the following methods to increase the power output of structures reported in the literature. Three types of structure were investigated: (1) the AlAs/InAs structure that promotes the formation of population inversion by promoting electron transport leakage, (2) the structure with a thin barrier layer that enhances electron transport, and (3) the structure with an active region with reduced Al composition that assists in the formation of population inversion. The gains and wavelengths of these structures were calculated using a simulator that uses a nonequilibrium Green's function. The results showed that the AlAs/InAS structure had the highest gain. On the basis of the simulation results, two types of QCL, the reference structure and the AlAs/InAs, structure were fabricated. The peak output of the laser in the AlAs/InAS structure increased 1.73 times, compared with that in the reference structure. The validities of investigating the increase in power output by bandgap engineering and simulating QCL characteristics were demonstrated.
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Paper Nr:	52
Title:	Improved Viewing Angle and Light Extraction Efficiency of Microcavity OLED with Corrugated Capping Layer
Authors:	Byung Doo Chin, Jeong-Yeol Yoo and Sung Min Jo
Abstract:	Simple and low-cost materials and process for the formation of light extraction layer of organic light emitting diodes (OLED) are important. However, in case of microcavity-driven OLED, microscale structure for improved light extraction of devices is not easily applicable due to the sever interference with efficiency and viewing angle limitation. In this work, various type of periodic and non-periodic corrugated pattern array for OLEDs were formed by soft lithographic process or spontaneous self-assembly after thermal annealing. Improvement of top emission OLED with microcavity-driven high efficiency were observed, while the angular dependence of light emitting spectra (viewing angle characteristics) was reduced at devices with larger features of corrugated non-periodic capping layer structure. Optical properties of devices were investigated in terms of the scale of periodic patterns and optical cavity effect. Methods in this work could be utilized as an effective tool for managing microcavity-driven performance of high efficiency OLEDs.
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Paper Nr:	119
Title:	Simulation and Experimental Validation of a Silicon Photonics Ring Assisted Mach-Zehnder Interferometer Filter
Authors:	Ana Clara Marques, Pedro Cabrita, Maria João Carvalhais, Catarina Novo, Mário Lima, Francisco Rodrigues and António Teixeira
Abstract:	This paper presents a comprehensive study on the simulation and laboratorial validation of ring assisted Mach-Zehnder interferometers (RAMZIs) for use as optical filters in demultiplexing systems in optical communication. The study explores the integration of a Mach-Zehnder interferometer (MZI) and an optical ring ressonator (ORR) to achieve a flat-top spectral response. The ORR and MZI are independently simulated before combining them into a RAMZI structure. The experimental results, obtained from a fabricated PIC on a SiOI platform, closely align with simulated spectrum, demonstrating the validity of the proposed model.
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