Table of contents

19–20 September 2022, Penang, Malaysia

The Photonics Meeting is an annual event organized by the Optical Society of Malaysia (OSM) in celebrating UNESCO International Day of Light. For this year, the 5^th Photonics Meeting 2022 (PM22) was held on 19^th and 20^th of September 2022 in collaboration with Universiti Sains Malaysia. PM22 with the theme "Exploring photonics breakthrough for humanity" has attracted 26 contributors that covers various topics on photonics including optical materials, laser physics, fiber optics and colorimetry. PM22 has been honoured with presentation from world renowned scientists from industry as well as international research laboratory and universities as the plenary and keynote speakers. PM22 would like to extend its great appreciation to all the committee members who have work diligently to ensure the smooth deliverance of this scientific event. Due to the Covid19 pandemic, the conference was fully conducted virtually through Cisco Webex platform hosted by School of Physics, Universiti Sains Malaysia. Each participant was given 10 minutes for their presentation and another 5 minutes for question and answer session. All submission has been thoroughly reviewed by the experts in the respective field and presented in this volume of Journal of Physics: Conference Series.

List of Editors, Keynote Speaker, Plenary Speaker, Organizing Committee are available in this Pdf.

All papers published in this volume have been reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing Publishing.

• Type of peer review: Single Anonymous

• Conference submission management system: Morressier and CMT

• Number of submissions received: 27

• Number of submissions sent for review: 26

• Number of submissions accepted: 26

• Acceptance Rate (Submissions Accepted / Submissions Received × 100): 96.3

• Average number of reviews per paper: 1

• Total number of reviewers involved: 14

• Contact person for queries:

Name: Ahmad Fairuz Omar

Email: fairuz_omar@usm.my

Affiliation: Universiti Sains Malaysia

A novel chalcone based pyrene (E)-1-(4-(1H-imidazol-1-yl)phenyl)-3-(1,5a1-dihydropyren-1-yl)prop-2-en-1-one (EIPDP) has been successfully synthesized by Claisen-Schmidt condensation reaction. The molecular structure was optimized using density functional theory (DFT) at B3LYP/ 6-311++G(d,p) basis set. In addition, molecular electrostatic potential (MEP) was obtained to study the intramolecular charge transfer (ICT) by introducing electrophilic and nucleophilic sites on the compound surfaces. Absorption UV-Vis spectra were performed experimentally and theoretically to study the electron transitions of the EIPDP. Further, the excitation states were characterized using the hybrid exchange-correlation functional of Coulomb Attenuated Method-Becke, 3-parameter, Lee-Yang-Parr (CAM-B3LYP) with the Integral Equation Formalism Polarizable Continuum Model (IEFPCM) in Dimethyl sulfoxide (DMSO) solvent at the same basis set. The nonlinear optical (NLO) properties were investigated using Z-scan techniques with continuous wave (CW) laser at 630nm. The NLO findings disclosed that the third-order nonlinear optical parameter (χ³) for the title compound is in the order of 10⁻⁶ esu.

In current study a careful and dedicated observation was done to investigate the effect of the externally applied optical field on electrolysis of water to produce hydrogen. As optical field sources, the green and red diode pumped solid state lasers (DPSSL) were utilized. Due to its non-absorbance characteristics in water, the green laser has had the largest impact on the generation/production of hydrogen. In order to dissociate hydronium and hydroxide ions during orientation toward polarisation of water, the electrical field's intensity must be high enough. The mechanism of optical field to expose the hydrogen production in water electrolysis has the capability to break the autoprotolysis and generate the auto-ionization. However, the presence of a sacrificial agent and a laser source combined to produce a better effect, resulting in a five-fold increase in hydrogen output compared to ordinary water electrolysis. UV-Vis and the gas chromatography was performed for supporting the research claim. The gas chromatogram was indicating a clear peak at retention time 1.47 minutes with abundance 338878 a.u. which predicts the purity and abundance of produced hydrogen.

In this work, dip coating process (DCP) was used to synthesize TiO2 nanoparticles (NPs). The photocatalytic nanostructured heterojunction was formed on ZnO nanoseeds (NSs) layer grown by radio frequency (RF) sputtering on flexible Teflon (PTFE) substrate. Series of characterizations and analyses reveal the morphology, optical, and structural properties of the nanocomplexes. These include several identified peaks observed by XRD. While, UV-Vis reflectance spectroscopy, photoluminescence (PL), and FTIR were utilized to determine the opto-characteristics, and to observe the presence of functional bonds involved in the growth of the heterojunction thin film. Based on the presented results, the heterostructures relying on a flexible substrate are believed to be highly promising for photocatalytic applications.

Prevention of stress in the asymptomatic stage of the plants could result in improved crop management. In this study, the water and light stress of three oil palm seedlings (Elaeis Guineensis) was examined by assessing the leaves' colour using CIELAB colour space. The oil palm seedlings were subjected to water stress for 33 days and then to water and light stress from 55 to 78 day (for 25 days). The variation of the colour of the leaves due to water stress was discussed in detail. The approach used in this study to identify the drought stress may allow for differentiating mild environmental and severe drought stress in oil palm plants and may be used for remote field-scale estimation of plant stress resistance and health.

In analytical process, measurement of concentration of solution based on colorimetric sensing is normally performed using commercial devices such as colorimeter and spectrophotometer. This approach has several disadvantages such as involving a large volume of reagent and analyte during testing and measurement, unextendible and expensive. Such problem can be solved by replicating its function using a simple optofluidic device with capability of carrying out colorimetric testing with low volume of analyte and reagent. Other benefits of optofluidic devices platforms includes ability to be expanded for automated sensing and mixing for various analytical based reaction. The measurement device works based on the absorbance of absorbance of light, which is related to Beer-Lambert law principles with LED and photodiode as its main optical components. The samples were prepared for concentration ranges between 0.2 to 2.0 M for testing. As a result, it is observed that these concentrations produce a linear voltage calibration curve with correlation coefficient, R² equal to 0.9944. By using the obtained calibration curve, the final absorbance calculation gives an acceptable linear absorbance concentration with R² equal to 0.9751 for the tested samples. As a conclusion, these microfluidic platforms not only have a good measurement performance, but also have advantages in terms of its portability and have potential to be implemented for real time application.

High resistivity silicon is increasingly becoming one of the subjects of interest in optimizing the performance of MIS photodetectors as it offers better bias responses compared to low resistivity silicon. The incorporation of thin AlN as the tunnelling insulator in MIS structure utilizing high resistivity silicon has shown promising photocurrent to dark current ratios, suggesting potential integration of the structure. In this work, the MIS structure on high resistivity silicon with AlN tunnelling insulator is simulated and empirically modelled using previous experimental work. The effects of substrate resistivity and AlN thickness are then evaluated. Simulation work shows good agreement with the previous experimental work, except for the photocurrent characteristics in the inversion region, where the recorded values are 10⁷ magnitude lower than the reported experimental values. The photocurrent characteristics for MIS structures on high resistivity silicon is recorded to be higher than the structures on low resistivity silicon. Meanwhile, both dark current and photocurrent increases with decreasing AlN thickness up until 1 nm. Lastly, no conclusive evidence from this simulation work to show any tunnelling behaviour in the inversion region for all cases.

This paper presents on the design and analysis of Dense Wavelength Division Multiplexing Passive Optical Network (DWDM-PON) which is the upcoming trend technology nowadays to transmit up to 40 Gbps data. Various modulation techniques such as Non-Return Zero (NRZ), Return-Zero (RZ) and duo binary coding are simulated in this DWDM-PON. Using OptiSystem software, DWDM-PON is designed and simulated for 32 channels with spacing of 100 GHz and bit rate of 10 Gbps. An Erbium Doped Fiber Amplifier (EDFA) and Dispersion - Compensating Fiber (DCF) is deployed in the DWDM design. It is found that duo binary modulation technique gives the best performance with minimum BER of 2.66x10^-19. From the simulation result, it also found that the proposed DWDM PON design is suitable to be deployed for current network.

The dosimetric properties of synthetic ZnO/Ag/ZnO multilayer film are investigated. The proposed dosimeter was prepared by radio frequency and direct current RF/DC sputtering and irradiated with X-ray doses up to 4 Gy. The properties of thermoluminescence (TL) such as glow curve, dose-response, homogeneity batches, sensitivity, minimum detectable dose (MMD), precision, kinetic parameters (activation energy E, frequency factor S), and percentage depth dose (PDD) were studied. The thin film appeared to have an excellent linear response, and the sensitivity was almost twice the commercial TLD. The readout of the homogeneity and PDD are the same properties of TLD-100. These desirable qualities demonstrated the versatility of this novel synthetic thin film in applications involving radiation detection.

Zinc oxide (ZnO) nanorods were formed on a glass substrate using chemical bath deposition (CBD) method for three hours at 96 °C. Doping of aluminum (Al) was realised by dipping into aluminum nitrate solution. XRD spectra shows reduced (002) peak related to the crystallinity of the synthesized ZnO with increasing doping concentrations. Doping with 35 mM exhibited highest Al concentration of 11.78 %. An apparent shift in bandgap energy with increasing doping concentration provides further evidence of doping occurring in the sample. Random lasing was observed at a pumping threshold of 9.0 mW and spectral width of 1.09 nm. Overall results indicate promising potential for random lasing to occur in ZnO nanorods doped under ex-situ doping conditions.

A tapered plastic optic fiber (POF) was developed and demonstrated for monitoring different concentrations of limonene. The working mechanism of the sensor was dependent on the evanescent field interaction between light and the POF tapered region. The tapered POF was fabricated using a polishing-etching method to accomplish different waist diameters of 0.7 mm, 0.65 mm, 0.6 mm, 0.55 mm, and 0.5 mm in a 2 cm sensing region. The experiment was carried out with a blue LED with a wavelength of 400 nm and the output voltage was observed. As the concentration of the limonene solutions increased from 20% to 40%, 60%, 80%, and 100%, the refractive index also increased to 1.39, 1.41, 1.43, 1.44, and 1.47, respectively. The sensitivity of the sensor increased as the tapered waist diameter was reduced. The key benefits of this sensor are its ease of handling and fabrication in comparison to other types of sensors.

The precipitation-spin coating technique is employed to prepare nanostructure ZnO quantum dot (QD) films at different thicknesses. The X-ray diffraction analysis reveals the polycrystalline thin film growth along (101) plane and crystallinity improvement with thickness rise. The increase in thickness causes an increase (5.14 - 7.73 nm) and a decrease (3.39- 3.22 eV) in grain size and bandgap respectively. At optimized thickness, the ZnO QD thin film exhibits 72 % transmittance with the lowest resistivity of 16.24 x 10^-2 Ωcm and highest carrier mobility of 15.38 cm²/Vs rendering it viable for potential utilization as an electron transport layer for perovskite devices.

To improve the Brillouin frequency shift (BFS) resolution measurement and processing time of the differential cross-spectrum Brillouin optical time domain reflectometry (DCS-BOTDR) fiber sensor, our team suggests employing the ensemble machine learning (EML) technique. Because it gave the best BFS resolution compared to the other T_L cases, we used the BFS distribution data recorded by the pulse duration T_L =14 ns case as ground truth to train the EML model in this work. After that, we tested the EML model for T_L =4, 60, and 90 ns cases. We improved the BFS resolution for all T_L situations by approximately 2.85 MHz, comparable to our resolution when T_L was equal to 14 ns. This result demonstrates that the EML algorithm is reliable, efficient, and highly accurate in its predictive capabilities. Additionally, we have documented a rapid processing time of approximately one second. In addition, we have successfully demonstrated 20 cm spatial resolution measurement for T_L =60 and 90 ns, which was not previously possible with the usual DCS-BOTDR signal processing method.

Surface plasmon resonance (SPR) sensors have many applications in detecting toxic gases, water pollutants, and biomarkers of many diseases. Surface plasmon resonance sensors are a good candidate for future sensing platforms due to their high sensitivity and fine resolution. However, the challenges of high cost, cross-sensitivity, and large amount of generated data need to be addressed to unlock surface plasmon resonance potential. Machine learning (ML) algorithms can address these challenges. In this short review, recent studies integrating the algorithms of Artificial Intelligence (AI) and Machine Learning (ML) with (SPR) sensing mechanisms for bio-detection applications are presented here. This short review shows how the integrated approach can help mitigate some of the challenges faced by traditional SPR sensing.

In this study, minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were estimated for three types of zinc oxide (ZnO) nanoparticles on a Gram-positive bacterial species: Streptococcus mutans. The structural properties of these nanoparticles, designated as ZnO-A, ZnO-K, and ZnO-Ax, were characterized using the techniques of field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. Both MIC and MBC were evaluated using a series of dilutions (serial dilution) in a 96-microtiter plate following the standard method CLSI M100-Ed32. The commercial ZnO-K nanoparticle had the largest average crystallite size, i.e., 42 nm followed by ZnO-A (37.5 nm), and ZnO-Ax (37.8 nm). ZnO-Ax was synthesized via post-oxygen annealing, while ZnO-A was prepared via energy combustion. All three ZnO nanoparticles yielded a similar MIC value, i.e., 0.156 mM, in S. mutans. However, the colony-forming unit (CFU/mL) at 0.156 mM varied among the ZnO particles. The ZnO-Ax nanoparticle had the lowest colony number in S. mutans, suggesting that the ZnO-Ax gave better inhibition towards the bacteria, probably due to its high surface area and O: Zn ratio (1.09) that enhanced the generation of reactive oxygen species generation for antibacterial activity compared to ZnO-A and ZnO-K.

This work demonstrate Neodymium Oxide (Nd₂O₃) film as a passive saturable absorber (SA) for pulse generation within C-band region. The saturable absorber was fabricated from Nd₂O₃ powder, and polyvinyl alcohol (PVA) was used to form a film. The all-fiber ring cavity configuration was used in the experiment. The Q-switching operated with the pump power from 60 mW to 120 mW. The repetition rate increases from 52 kHz to 77 kHz, while the pulse width shown decrement of 7.4 µs to 5.3 µs. The signal-to-noise ratio obtained of the fundamental frequency is 64 dB. The maximum output power and pulse energy are 3.6 mW and 4.6 nJ respectively. The maximum peak power obtained is 0.87 mW.

Light Fidelity (Li-Fi) is a wireless technology that utilizes light emitting diodes to convey data. Li-Fi has emerged as a promising alternative to radio frequency communication technology in recent years. This paper examines the performance characterisation between NRZ-OOK and carrier-less amplitude-phase modulation (CAP-2, CAP-4 and CAP-8), within a simulated Li-Fi environment. For the parameters of interest, the eye pattern, bit error rate (BER) and constellation diagram are reported. As no distance is specified in the simulation, the BER for CAP is zero, allowing an ideal transmission to be emulated. The scatter diagram increases as the number of CAP modulations increases. For the eye pattern, CAP modulation provides a better visual representation of how noise might affect system performance compared to OOK modulation.

The growth of ZnO nanorods (NRs) have been performed by chemical bath deposition (CBD) method on ITO glass substrate. The optical properties along with the structural of ZnO NRs were studies by Field Emission Scanning Electron Microscope (FESEM), energy-dispersive X-ray (EDX), X-Ray Diffraction (XRD), and UV-Visible (UV-Vis) analysis. A 100 nm of Cu metal and Pd metal were deposited on top of synthesized ZnO NRs via sputtering. The electrical properties including I-V characteristics, rectifying ratio, Schottky Barrier Height (SBH) and ideality factor were investigated. Difference in work function for both metals resulting in different I-V characteristics, hence different value of rectifying ratio, SBH and ideality factor. The Cu sample possessed rectifying ratio, SBH and ideality factor of 1.07, 0.66 eV and 6.1 respectively, while Pd sample exhibits 87.84, 0.43 eV and 5 respectively. These intriguing values made possible for these metals to potentially serve as contact for ZnO-based optoelectronics devices, e.g LED, and random laser.

We present the growth of ZnO nanorods (NRods) prepared by chemical bath deposition on 100 nm and 200 nm ZnO seed layer sputtered on glass substrate. The structural and optical properties of ZnO NRods were investigated by Field Emission Scanning Electron Microscope (FESEM), energy-dispersive X-ray (EDX), X-Ray Diffraction (XRD), and UV-Visible (UV-Vis) analyses. Random lasing (RL) emission behaviour was characterized by pulsed-wave micro-photoluminescence (pw µ-PL) analysis. Changed in seed layer thickness on 100 nm and 200 nm, allowing for greater particle size of ZnO NRods to form, while maintaining the preferred diffraction of self-organized growth direction with high-quality c-plane. The reduction in optical properties of ZnO NRods also lowering random lasing emission threshold toward higher excitation power density from 37.86 kW/cm² to 95.40 kW/cm².

Self-image interference in a single mode-no-core-single mode fiber plays an important role especially for length optimization before acting as a sensor. The interference can be observed through optical simulation software. Past literature has successfully demonstrated the interference via COMSOL Multiphysics®, but the simulation was not restricted to the use of important domains and settings such as perfectly matched layer and surrounding domain causing imprecise simulation results. This paper proposes a simulation of self-image interference in a single mode-no-core-single mode fiber by using the wave-optics module in COMSOL Multiphysics® software. The beam propagation method is used to observe the self-image interference for different self-image indexes ranging from one to four indexes while the self-image length is obtained from the theoretical calculation before a simulation is carried out. The results show that accurate results can be obtained with restricted simulation settings. The number of the self-image index and self-image length produced by the simulation are similar to the calculation. The self-image point is located exactly at the calculated length with a four-decimal point 0.0000 difference, thus overcoming the limitation of the simulated previous work. In the future, the simulation settings and results can be used for reference to simulate the single mode- no-core-single mode fiber structure.

The phenol red is commonly used in cell culture medium as visual pH indicator by changing its color from darker red color to the orange-yellowish color as the pH is changing from neutral to acidic level. The color change of phenol red is hardly to be determined by using naked eyes that will be interpreted differently by different person. Thus, this study is executed to develop a specialized colorimeter for phenol red pH measurement by using Raspberry Pi as a microcontroller unit, green LED as a light source and photodiode in tandem with capacitor as a light sensor. The Raspberry Pi calculated the capacitor charging time which is in relative to the amount of light sensed by the photodiode. Based on the results, the capacitor charging time can be related to the pH value by using non-linear relationship with high accuracy of R² = 0.8946 and RMSE = 0.4447. This study successfully introduced the development of low-cost system for phenol red pH measurement by applying the capacitor charging time which is in correspond with the absorbance value.

Squeezed states of light in a three-channel nonlinear coupler with second-order nonlinearity using the phase space method and the analytical perturbative method is reported in this paper. The system is studied under the frequency mismatch condition, where the frequencies of the pump mode are not common. The effect of frequency mismatch on the generated squeezed states is investigated. We have found that the frequency mismatch does significantly affect the behavior of the generated squeezed states only at higher values of linear coupling between the waveguides. By increasing the frequency mismatch, the squeezing pattern also evolves from a collapses-revivals-like squeezing into a constant oscillation.

Using the quasiprobability positive P of phase space representation, we examine the features of squeezing over two octaves of frequency difference with each octave integrating two-channel nonlinear waveguides. The second harmonic coupling of the light fields is taken into account in the current arrangement. We discovered that single-mode squeezing is decreased by second harmonic coupling.

Surface plasmon resonance sensors have numerous applications in the discovery of poisonous gasses, water toxins, and the biomarkers of numerous infections. Surface plasmon sensors are a great candidate for future detecting stages due to their high sensitivity and fine resolution. A surface plasmon resonance sensor is also built for food safety using a Kretschmann setup with a gold coated prism. The setup was used to detect the analyte solution with concentrations 0%-3%. The sensor showed a good response and stability.

New type plasmonic sensitizer, titanium nanoparticles (Ti NPs) shown potential in enhancing photoluminescence of rare-earth ions (REIs) as doped into magnesium zinc-sulfophosphate (MZS) glass for optical to optic application. Here, neodymium ions (Nd³⁺)-doped MZS glass with Ti NPs inclusion gone heat treatment (HT) at 450°C for 6 and 12 hours in order to tune the NPs size and tailor their plasmonic strength. The sample was characterized using X-ray diffractometer (XRD), high-resolution transmission electron microscope (HRTEM), and photoluminescence (PL) spectrometer. Heat treatment (HT) grows Ti NPs with a mean size ≈ 16 nm. The SPR bands are probed around 585and 739 nm. The SPR band intensities change with HT duration. The NIR PL bands were perceived around 878 nm, 1050 nm and 1322 nm corresponding to ⁴F_3/2→⁴I_9/2, ⁴F_3/2→⁴I_11/2 and ⁴F_3/2→⁴I^13/2 transitions, accordingly. The PL transition ⁴F_3/2→⁴I_9/2 (878 nm) and ⁴F_3/2→⁴I_13/2 (1322 nm) is enhanced about 1.44 and 1.52 times respectively, after 12 hours HT. The results show that HT enhances PL through SPR amplification. These findings may be useful in developing solid-state lasers and optical materials.

This research is to study the possibility of fabricated zinc borosilicate glass doped with neodymium trioxide (ZnO-B₂O₃-SiO₂:Nd₂O₃) to be a new material candidate for TLD. TGA analysis is an analytical technique used to determine a thermal stability of materials and its fraction of volatile components by monitoring rate heat flow to and from a sample and the weight changes, as temperature is changed at a constant rate. Data obtained is used to determine temperature of transitions and melting points of substances. Glass Transition Temperature (Tg) for the glass TLD sample produced obtains are between 369.01 °C - 371.74 °C and maximum annealing and reading temperature are set to be 350 °C that are below the minimum T_g values. X-Ray Diffraction (XRD) analysis has proven the samples fabricated are amorphous. Effective atomic numbers (Z_eff) are in the range of 20.44-21.60. Glass TLD samples showed good linearity with TL response and faced 45.22%-59.37% fading after 30 days. Glass TLD samples also have been tested for their reproducibility ability for 6 cycles of annealing, irradiate and reading process and the reading showed a small range of different.