The Speakers

ABSTRACT | Distributed Fiber Optic Sensing (DFOS) is an advanced sensing technology for measuring and monitoring physical parameters across large areas. In this talk, a comprehensive overview of key technologies that form the foundation of DFOS: Brillouin-based DFOS such as  Brillouin Optical Time Domain Reflectometry (BOTDR), Brillouin Optical Time Domain Analysis (BOTDA), and Rayleigh-based Distributed Acoustic Sensing (DAS) will be explained. Each of these technologies will be explored in terms of their principles, operational mechanisms, and unique advantages for real-time, high-resolution sensing over long distances. The second part of the talk will focus on the advancement of DFOS technology in Malaysia, from its early research stages to its potential applications in various sectors. We will explore several techniques that have been proposed to improve the signal processing, sensor sensitivity, noise management. While field-deployable systems are still under development, this presentation will highlight ongoing research efforts aimed at pushing the technology towards practical deployment. 

ABSTRACT | This study presents the development and performance evaluation of a broadband wavelength-interrogated Long-Range Surface Plasmon Resonance (LRSPR) sensor for the sensitive detection of high-viscosity liquids, including edible oils and oil mixtures. The sensor's extended propagation distance of surface plasmons allows for precise detection of refractive index changes in high-viscosity samples. Initially, the sensor was applied to the detection of the carcinogen dinitrochlorobenzene in edible oils, where it demonstrated a strong correlation (R² = 0.9536) between wavelength shifts and contaminant concentration. The sensor achieved high sensitivity (0.0153 nm/ppm) in palm oil samples, with a superior figure of merit (FOM) and resolution, surpassing conventional surface plasmon resonance (SPR) systems. Further investigation explored the sensor's performance across temperatures ranging from 30°C to 70°C. The results revealed that at higher temperatures, the resonance wavelength shifted to shorter wavelengths (blue shift), while the full width at half maximum (FWHM) increased and the peak intensity decreased, indicating a broader and less intense spectral response. The broadband LRSPR sensor reliably detected high-viscosity oil mixtures, with increased sensitivity for concentrations ranging from 0% to 45% at elevated temperatures. At lower temperatures, detection capability was limited due to the increased viscosity of the samples. These findings demonstrate that broadband LRSPR is a promising technique for detecting and monitoring high-viscosity liquids, offering potential applications in industrial processes, environmental monitoring, and quality control, where temperature variations are common.

ABSTRACT | The development of high-sensitivity optical sensing devices is critically dependent on the incorporation of well-engineered sensing materials. Polysaccharides and metal-organic frameworks (MOFs) have attracted significant attention due to their outstanding physicochemical properties and structural tunability. This presentation highlights critical considerations in the design of such materials for the sensitive recognition of target analytes, emphasizing both physical and chemical modifications that enhance their performance. By tailoring their structures—particularly through the introduction or modification of functional groups—these materials can be optimized to enhance interactions with analytes, such as hydrogen bonding, coordination, or electrostatic attraction. The integration of polysaccharides and MOFs with optical sensing platforms is expected to improve detection sensitivity in complex environments. This talk underscores the role of structural design in transforming these materials into high-performance components of optical sensors. 

ABSTRACT | Optical sensors play a crucial role in environmental monitoring and material science, providing valuable spectral data for advanced analytical applications. However, traditional analytical methods without machine learning often rely on linear assumptions, manual feature selection, and limited data integration, making them less effective for capturing complex relationships in material performance. These limitations hinder the accurate prediction of photocatalytic efficiency, especially when dealing with diverse nanocomposite structures and varying environmental conditions. This study explores the potential of Transformer-based machine learning (ML) models for analyzing copper-based nanocomposites in photocatalytic dye degradation. Unlike conventional ML approaches that rely solely on either tabular or image data, our framework integrates both data types to enhance predictive accuracy. The objectives of this research are to develop a comprehensive dataset of copper-based nanocomposites and their photocatalytic efficiency, design machine learning models to predict degradation performance, and evaluate their performance against existing predictive methods. Our methodology involves dataset curation, feature extraction, and training transformer models with multi-modal data integration. Comparative analysis with traditional models demonstrates that the proposed approach significantly improves prediction accuracy, offering a robust tool for optimizing nanocomposite design in environmental applications.

ABSTRACT | Molybdenum disulfide (MoS2), a layered two-dimensional (2D) transition metal dichalcogenide (TMDC), exhibits strong light–matter interactions, tunable bandgaps, and remarkable optical anisotropy, making it a compelling candidate for emerging photonic and optoelectronic applications. The intrinsic defects in MoS₂, particularly sulfur vacancies, play a central role in determining its electronic, optical, and electrochemical properties. However, achieving precise control over defect concentration, crystallinity, and conductivity remains a significant synthesis challenge. This work reports on the controlled fabrication of MoS2 thin films using vapor-phase sulfurization and radio-frequency (RF) sputtering, focusing on tuning film quality through variations in temperature, sulfurization time, and chamber pressure. Emphasis is placed on key findings from the dual approach: (1) the modulation of electrical and optical properties via growth temperature, pressure, and sulfurization time, and (2) the correlation between Raman-active defect modes and conductivity type transitions (n-type ↔ p-type). Transitions between n-type and p-type conductivity are linked to sulfur vacancy dynamics, while morphological studies reveal enhanced grain compaction and surface uniformity under optimized processing conditions. By correlating synthesis conditions with electrical, morphological, and defect-related behavior, this work demonstrates the potential of MoS2 not only as a functional layer in thin-film photovoltaics but also as an active material for photodetectors, waveguides, and modulators. Supported by recent literature on nonlinear optics, exciton–plasmon coupling, and hybrid nanophotonic integration, MoS2 emerges as a tunable, scalable platform for next-generation light-based technologies.

ABSTRACT | The accurate and real-time monitoring of oxygen concentration is vital in various fields including environmental monitoring, biomedical diagnostics, industrial process control, and aquatic ecosystem management. This study presents the development and characterization of an optical fiber oxygen sensor utilizing luminescent probes as the sensing element. The sensor is based on the principle of luminescence quenching, whereby the intensity or lifetime of luminescent emission from specific dyes decreases in the presence of molecular oxygen. In this work, a ruthenium-based complex was immobilized on the tip of a silica optical fiber using a sol-gel matrix, forming a stable and sensitive sensing layer. The optical setup comprises a blue LED as the excitation source, a bifurcated fiber optic system for simultaneous excitation and signal collection, and a photodetector connected to a spectrometer for emission analysis. The sensor's performance was evaluated in terms of sensitivity, response time, repeatability, and long-term stability under varying oxygen concentrations in both gaseous and aqueous environments. Experimental results demonstrate a clear correlation between the luminescent intensity and the oxygen concentration, with high sensitivity observed in the low oxygen concentration range. The sensor exhibited a response time of less than 10 seconds, good linearity, and minimal signal drift over time. Additionally, the probe showed excellent selectivity, with negligible interference from humidity or temperature fluctuations under controlled conditions. The findings confirm the feasibility and reliability of using luminescent probe-based optical fiber technology for oxygen sensing applications. The developed sensor is compact, cost-effective, and suitable for integration into portable monitoring systems. Future work will focus on further miniaturization, multiplexing for multi-parameter sensing, and deployment in real-world environmental and biomedical settings.

ABSTRACT | A supervised machine learning (ML) algorithm is proposed for measuring refractive index (RI) values both below and above the RI of the fiber material using a multimode interference (MMI) fiber sensor. The sensor is constructed by splicing a coreless multimode fiber (CMF) segment between two single-mode fiber (SMF) leads. Measurement of low and high RI regimes is accomplished through the decision tree (DT) regression algorithm. The trained model algorithm demonstrates a wide dynamic range in RI measurement, covering the ranges of 1.30–1.39 (low RI regime) and 1.46–1.55 (high RI regime) without any RI ambiguity, achieving model accuracy of 99.77%. The guided and leaky modes mechanisms within the all-silica-based structure of the CMF are fundamentally insensitive to temperature, making it highly practical for deployment in conditions with varying temperatures without the need for any compensating scheme. This work highlights that AI-powered MMI optical fiber sensors represent the next generation of photonic sensing systems, offering highly accurate, wide-range refractive index measurements with enhanced robustness against temperature variations.

ABSTRACT | Tapered microfibers are attracting significant interest due to their potential to improve optical trapping efficiency in nanotechnology and biomedical fields. The primary aim of this study is to fabricate various tapered microfiber structures, including bi-tapered fibers, micro-peanut probes, and one-sided tapered probes, using heating-pulling and cleaving methods. These structures are designed to strengthen the evanescent field for optical trapping applications. To optimize surface plasmon resonance generation, the fabricated tapered fibers are coated with noble metals—gold nanoparticles and platinum thin films—using drop casting and sputtering techniques, respectively. The hybrid coating of gold nanorods and platinum on the micro-peanut probe structure successfully excites surface plasmon polariton by up to 90%. In conclusion, the enhanced tapered probe, featuring a plasmonic-based micro-peanut structure, effectively generates strong evanescent waves for optical trapping applications.

ABSTRACT | Nanomaterials are widely used for dye degradation due to their high surface-to-volume ratio and efficiency. Magnetic nanomaterials can be easily retrieved after the degradation process and reused multiple times, enhancing sustainability. Zinc Oxide/Iron Oxide magnetic nanocomposite was synthesized using a two-step laser ablation in liquid (LAL) technique. First, an iron target was ablated in deionized water to obtain a colloidal iron oxide solution. Next, a zinc target was ablated in this iron oxide solution to synthesize the ZnO/Fe₂O₃ nanocomposite. The produced nanocomposite was characterized using UV-Vis spectroscopy, XRD, EDX, and TEM analysis. It was then utilized as a photocatalyst to degrade methylene blue dye under a UV light source, and its photodegradation efficiency was evaluated. The same photocatalyst was also tested in successive degradation cycles to assess the decline in photodegradation efficiency per cycle. The results demonstrate that the magnetic ZnO/Fe₂O₃ nanocomposite synthesized via laser ablation in liquid is a sustainable and effective solution for dye degradation.

ABSTRACT | Hydrogen is widely recognized as a clean energy carrier, yet its flammability and invisibility pose significant safety challenges in industrial and environmental contexts. This talk explores recent advancements in optical fiber hydrogen sensors enhanced with nanostructured materials, specifically molybdenum trioxide (MoO₃) and emerging MoS₂-based nanocomposites. Leveraging tapered fiber geometries and innovative material engineering, these sensors offer high sensitivity, selectivity, and rapid response—critical features for early leak detection and emission monitoring. The presentation will share key insights into fabrication techniques, sensing performance, and the material–structure relationship. While current work focuses on standalone systems, future integration with IoT frameworks will be discussed as part of a vision for real-time, networked environmental monitoring. This research reflects the evolving intersection of photonics, nanotechnology, and sustainable energy technologies.

ABSTRACT | The integration of functional nanomaterials into surface plasmon resonance (SPR) sensor interfaces offers promising routes to improve sensitivity in metal ion detection. This work explores the use of carbon-based nanomaterials such as carbon quantum dots, multiwalled carbon nanotubes, and nanocrystalline cellulose to engineer thin film structures on gold surfaces. Characterization using AFM, FTIR, and UV-Vis spectroscopy confirms their impact on surface morphology and optical behavior. Experimental results demonstrate improved interaction with metal ions, supporting the potential of nanomaterial-enhanced SPR sensors for environmental sensing applications.

ABSTRACT | Ultrafast pulse laser generation in photonics has gained significant interest in fundamental science and various industries, such as telecommunications, sensing, industrial processing and medicine. Passively Q-switched and mode-locked fiber lasers are recent developments that produce efficient pulse lasers by incorporating gain medium, saturable absorber (SA) materials and SA hosts. In this research, tapered fibers were fabricated and characterised using the flame-brushing technique, with a tapered waist of approximately 7 µm.

ABSTRACT | A label-free optical biosensor presents an innovative solution for biochemical detection, besides tapered optical fiber (TOF), Tilted fiber Bragg gratings (TFBGs) have been shown to have distinctive properties that enable the creation of highly precise sensors, especially in biochemical realm, while maintaining cost efficiency in both manufacturing and signal interrogation. This review compares both the TFBGs and TOF, Emphasizing the latest developments in their fabrication techniques, sensing mechanisms, and limitations. Most recent achievements of both will be discussed through examples from the literature. Pros and cons will be assessed and discuss the potential advantages of combining both structures.

ABSTRACT | A novel, compact directional inclinometer uses femtosecond laser-inscribed edge-core parallel gratings (ECPGs) on opposing sides of a fiber core. The ECPGs exhibit opposite reflection intensity responses to fiber curvature. A hinge-based structure with a metal load translates inclination into this curvature, which is then measured by monitoring the reflected intensities. Differential signal processing mitigates bending loss and input light intensity fluctuations. The sensor demonstrates good stability and durability, with a linear sensitivity of 0.148 dB/° (R² = 0.997) over an inclination range of ±80°.

ABSTRACT | A decade ago, dark pulse was defined as “A solution looking for a problem”. To date, dark pulse has proven its potential in telecommunication, sensing and other industries. Dark pulse exhibits extraordinary propagation properties which draws research interest in dark pulse as a replacement for bright pulse. The research on development of dark pulse was slow after it was first demonstrated as it required careful selection of laser cavity parameters. Here, we present the progression dark pulse generation and to classify them accordingly as Nonlinear Schrodinger Equation (NLSE) dark pulse, Cubic-Quintic nonlinear Schrodinger Equation (CQNLSE) dark pulse and domain wall (DW) dark pulse.

ABSTRACT | Palm oil is a globally important commodity, with Indonesia and Malaysia as the leading producers. Malaysia, in particular, upholds sustainability through initiatives such as the Malaysian Sustainable Palm Oil (MSPO) certification. Despite these efforts, the industry continues to face challenges related to environmental impact, climate variability, and the need for consistent quality control across production processes. To address these issues, INSPECTRA—a real-time, inline Near-Infrared (NIR) spectroscopy analyzer—has been introduced as an advanced solution for crude palm oil (CPO) quality monitoring. The system enables rapid, non-destructive, and reagent-free measurement of critical quality parameters, including free fatty acids (FFA), oil content, water content, and non-oil solids. INSPECTRA integrates chemometric modelling and predictive algorithms for real-time classification and quantification, enhancing the accuracy and efficiency of the quality assessment process. Its inline optical sensor probe is engineered to withstand high temperatures and pressures, making it suitable for continuous industrial monitoring. By minimizing manual sampling and providing reliable, real-time data, INSPECTRA supports process optimization, reduces operational costs, and aligns with both MSPO and Roundtable on Sustainable Palm Oil (RSPO) standards. Beyond palm oil, its adaptable design offers potential applications in agriculture and food processing, reinforcing its value as a versatile tool for sustainable production and environmental stewardship.

ABSTRACT | This talk presents recent advances in confocal and fluorescence optical imaging using two imaging configurations: a fibre cantilever-based endoscopic scanner and a standard non-scanning microscope setup. The developed mixed-mode imaging system employs single- and multimode fibre pair for light delivery and back-scattered signal detection. Additionally, the with the multiwavelength reflectance techniques, this operation could enhance contrast and spatial detail across both platforms. Imaging of cellular and plant samples demonstrates the complementary strengths of each modality—cladding mode for bright cellular imaging, multimode core for surface profiling, and carbon quantum dots (CQDs)-based fluorescence for enhancement of visualisation of the target sample. In the standard microscope configuration, confocal reflectance and fluorescence imaging enable detailed structural visualisation of the target sample. Additionally, the integration of multi-wavelength reflectance confocal microscopy allows for multispectral imaging and enhanced morphological analysis. For the endoscopic scanner, a passive aperture reflector was introduced to enable real-time feedback control of resonance frequency and cantilever tip position, improving scanning stability and image fidelity. Together, these innovations highlight the potential of hybrid optical imaging systems in delivering comprehensive, high-resolution visualisation for biomedical and cellular imaging applications.

ABSTRACT | Accurate vibration detection is critical in engineering and industrial applications, yet traditional sensors often face limitations in sensitivity and frequency selectivity, particularly under harsh conditions. This study explores the performance of Fiber Bragg Grating (FBG) sensors coated with Polydimethylsiloxane (PDMS) for detecting small-scale vibrations, aiming to overcome the limitations of bare FBG sensors such as reduced sensitivity and instability at higher frequencies. PDMS was selected as the coating material due to its favorable mechanical and optical properties, potentially enhancing the sensor's responsiveness to mechanical strain. The experimental setup involved a cantilever-based system, with vibration frequencies ranging from 0 to 100 Hz. An Amplified Spontaneous Emission (ASE) light source (wavelength range: 1530–1600 nm) and an Optical Spectrum Analyzer (OSA) were used to monitor Bragg wavelength shifts corresponding to vibrational inputs. Comparative analyses were conducted between PDMS-coated and bare FBG sensors to evaluate improvements in sensitivity, frequency resolution, and signal stability. Results showed that PDMS-coated FBG sensors demonstrated improved spectral stability and reduced optical power loss across the tested frequency range. The coating enhanced the mechanical robustness and environmental resistance of the sensors, making them more suitable for long-term and high-demand applications. However, a slight trade-off in sensitivity was observed, suggesting the need for further tuning of coating thickness and material composition for frequency-specific applications. This research highlights the potential of PDMS-coated FBG sensors for reliable vibration monitoring in structural health diagnostics, industrial machinery, and fault detection systems. By enhancing durability without significantly compromising performance, PDMS-coated FBGs represent a promising advancement in optical fiber sensing technology for use in complex and dynamic environments.

ABSTRACT | Formaldehyde (CH₂O), a toxic, colorless, and flammable gas, is widely used in various industries and household products. Prolonged exposure to formaldehyde poses serious health risks, including irritation of the respiratory tract and an increased risk of cancer. Current formaldehyde detection methods often suffer from limitations such as low sensitivity, high cost, and impracticality for broad adoption in residential and industrial settings. This research explores the development of a novel formaldehyde sensing solution utilizing tapered optical fibers (TOFs) coated with Rhenium Disulfide (ReS₂). The study focuses on fabricating TOFs with precise heating length 3mm and waist diameter (5µm and 10µm) using the heat and pull method and characterizing TOF with ReS₂ coatings. The TOFs performance has been tested by using tunable light source and optical power meter. Experimental evaluations are carried out by exposing the TOFs to formaldehyde vapor at concentrations of 1%, 2%, 3%, 4%, and 5% at different relative humidity conditions of 30% to 90%. Results depicted that the 5µm TOF has better stability and sensitivity for formaldehyde sensing as compared to 10µm TOF. Additionally, coating the TOF with Rhenium Disulfide (ReS₂) improved the sensitivity by 60-80%. The optimized sensor achieved the sensitivity of -0.05839 dB/%RH and linearity over 95%. The measurements showed excellent stability when all tested concentrations on both TOFs were maintained for 600 seconds at 90% RH. This proves that it’s demonstrated the precise formaldehyde sensing for environmental sensing applications.