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On behalf of the conference committee, I feel extremely glad to welcome all experts and participants to the International Laser Technology & Optics Symposium 2019, iLATOS 2019. We thank all participants for your continuous support to iLATOS conference series. We are so excited to have you all here to participate to our iLATOS 2019, organized by Laser Center, Universiti Teknologi Malaysia.

iLATOS 2019 provides a binding platform for all academicians, researchers, and experts to get together to share current knowledge and findings in the area of, but not limited to laser technology and optics fields. We hope that the conference could provide a meaningful networking and collaborative ties among researchers in their fields.

Finally, I would like to express my gratitude towards you all who sincerely contributed to this event in order to make it a success. This wouldn't have been possible without the support of each and every one present here.

iLATOS 2019 is an international forum for researchers, academicians, engineers and industry players from various fields of laser & electro optics with different experiences and backgrounds. iLATOS 2019 creates opportunities to present research results, discuss current issues and exchange views that may create mutual interest. Furthermore, it also acts as a bridge to transfer research & development output to the applications which match the industrial requirements as well as user's expectations. iLATOS 2019 offers a comprehensive view of theoretical and experimental laser research and applications. Articles cover every aspect of modern laser physics and quantum electronics, emphasizing physical effects in various media (solid, gaseous, and liquid) leading to the generation of laser radiation; peculiarities of propagation of laser radiation, problems involving impact of laser radiation on various substances and the emerging physical effects, including coherent ones; the applied use of lasers and laser spectroscopy; the processing and storage of information.

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

Color concentration is a key parameter to mark lubricant product specifications. Lubricant color does not necessarily indicate product quality, but the grade's color range can indicate possible contamination by another product. This study aims to design a side-polished fiber to measure color concentration in lubricants. The sensor is obtained by stripping the cladding of 1 mm polymer optical fiber. The side-polished fiber weaken light intensity due to the absorptive properties of color concentrate for visible light. The light source in this study is tri-color LED and the OPT101 as a light detector. Light passing through the fiber is converted by the detector into a voltage output. The results showed that the sensor is capable of detecting the concentration of color with measurement ranging from 10 mg/L to 200 mg/L. The output voltage of sensor's sensitivity is up to 0.039 (mg/L)/mV, 0.042 (mg/L)/mV and 0.047 (mg/L)/mV for the red, green and blue light sources respectively. The average linear correlation is 97.3 % in liquid lubricants. The designed sensor could be applied in ASTM D-1500 for color scale measurement of lubricant oil products.

Pure spherical-like SnO₂ and agglomerated spherical SnO₂/TiO₂ nanostructures (NS) films were effectively synthesized via hydrothermal route and modest combination of pulse laser ablation besides hydrothermal (PLAL-H) methods, respectively. The as-prepared samples were deposited on glass substrates at growth temperature 100 °C and characterized by FESEM, X-ray diffraction, and UV-Vis absorption and Photoluminescence (PL) measurements. Both samples exhibit a pure tetragonal rutile and anatase polycrystalline structure. The PL spectrum of pure SnO₂ Ns reveals five emission peaks in UV and visible regions. In contrast, a red shift in UV emission peak was clearly observed in SnO₂/TiO₂ nanocomposite spectrum and disappeared all visible emission peaks. Moreover, the samples as photocatalysts films were examined under sunlight irradiation driven photodegradation of methylene blue (MB) dye. The findings exposed that the photodegradation efficiency toward MB dye at maximum irradiation time 150 min was mostly similar around 21.5 % of both as-growth films.

This study investigates the effect of radiation doses of 4.78MeV energy of alpha particles emitted from radium radioactive source (Ra²²⁶), which gives an equivalent dose rate of (5mrem/h) with an activity of (60KBq ), on the optical properties of 350nm thickness of the ZnO thin films doped 6% rate of indium (In) that prepared by spray pyrolysis technique. The study of the optical properties included energy gap, reflectivity, absorption coefficient, refractive index, extinction coefficient, real and imaginary insulation constant by recording the transmission and absorption spectra of photons have wavelength range of 300-1000nm before and after exposing the thin film to α-particles to radiation doses of 125, 250 and 500mSv by exposing them to different time periods. When ZnO:6%In thin films exposed to radiation dose, the results generally showed decreasing of the energy gap value, a slight variation in the values of reflectivity, absorption coefficient, refractive index, extinction coefficient, real and imaginary insulation constant at the low dose (125mSv), and a significant variation in the values of these properties at higher doses (250, 500mSv) with a variation in behavior of the curves with the increasing of doses values.

Every single day, a large amount of fish dies from infection such as hyperoxia-induced gas bubble disease consequences by unusual dissolved oxygen (DO) level due to the natural occurrences and human-caused processes of supersaturated water. We are concentrating on the issue of sustainability – an issue of great importance and where this interdisciplinary area has the potential to make a profound impact. We need to step up our game by introducing DO sensing and monitoring at a large scale to overcome this global environmental issue. DO is known as oxygen saturation, one of the most critical parameters in accessing water quality, and necessary to be kept at a sufficient level for the survival of many forms of aquatic biodiversity. Hence, this review article mainly focuses on the potential of optical glass micro-fibre transducers for DO sensing and monitoring, and its contribution toward water security impacts - as part of the Sustainable Goals Development blueprint. The growing body of literature associated with five main work packages i) research motivation of water security, ii) research market analysis discussing the perspective on size, share, growth, trends, and forecast, iii) typical approach on characterising DO level as compared to the optical glass micro-fibre based transducers, iv) conventional design of the optical glass micro-fibre based transducers and v) mechanism of light modulation characteristic in the optical glass micro-fibre based transducers, are highlighted in order to gain a better understanding on the development and progress of optical glass micro-fibre as a transducer for DO sensing and monitoring that can change our life for the better. Finally, several recommendations for future work are presented at the end of this study for the reference of future readers.

Discovery of materials which exhibit large real third-order optical nonlinearities have recently become the topic of a broad scientific interest, due to its potential applications in many areas especially in the field of all-optical signal-processing. Here in this work, we report a preliminary investigation on the third-order nonlinear optical (NLO) response of different type of trace metal ions in nitric acid standard solution. A facile and rapid single beam z-scan technique incorporating 532nm diode pump solid state laser was employed to study the response of Lead (Pb), Cadmium (Cd), Mercury (Hg), Zinc (Zn), Aluminum (Al) ions towards NLO properties. Nonlinear refraction (NLR) response of the heavy metal samples were recorded from closed-aperture output and the maximum values of nonlinear refractive index, n₂ for all Pb, Cd, Hg, Zn, Al were recorded at 1.96355×10⁻⁹, 3.38228×10⁻⁹, 9.36907×10⁻⁹, 8.67559×10⁻¹⁰,3.28211×10⁻⁹ cm²W⁻¹ respectively. Based on the experimental findings, the negative sign of the nonlinear refractive index values successfully indicates that the samples exhibit nonlinear self-defocusing effect, which is further expected to have potential applications in all-optical devices.

A non-contact fiber optic displacement sensor was used for sugar concentration sensing. A concentric fiber optic bundle and sucrose solutions were used as the fiber probe and sugar samples respectively. Concentration of samples used were in the range of 9% to 33% weight percentages. The fiber probe was displaced above the sample surfaces and displacement curves were recorded. There were two peaks were observed in the displacement curve for each sample. The distance between peaks increases linearly as concentration increases and it was used to evaluate the sensing performance. In term of the performance, the sensitivity and linearity obtained were 0.08295 mm/% and 96% respectively.

Solar cells lose high percent of their capacity as a result of insufficient solar radiation, due to changing of the solar angle of projection during the day. Thus this research aims to increase the cell efficiency by a novel method which is based on collecting rays in the convex focus and dispersed in the concave lens, to make the rays always perpendicular on cells. To achieve this purpose, glass balls with a diameter of 10 mm were used and arranged on the cell area. This work found an obvious increasing in the cell efficiency, where it is possible to have an increasing in generating voltage by an estimated 7.53%, and the current 1.086% by this novel method.

In this work, Fibre Bragg Grating (FBG) and no-core fibre (NCF) sensors been investigated in different surrounding refractive index (SRI). FBG with 1550 nm wavelength attached with 5 cm length of NCF is used as SRI sensing probe. The sensitivity of the system was evaluated in different types of solutions which are ethylene glycol (18 % EG, 40 % EG, 60 % EG, 80 % EG, 100 % EG) and glycerol at room temperature. The dependence of the FBG and NCF wavelengths shift in spectral response versus different SRI has shown a linear relationship. The sensitivities of the system were 14.02 nm/RIU and 84.10 pm/RIU for FBG and NCF respectively.

Fiber Bragg grating (FBG) becomes one of the favourable sensing elements in current technology. In this study, FBG was chosen as the temperature sensor to validate the performance in different liquid samples and surrounding refractive index (SRI). FBG was chosen for the purpose due to its super sensitive sensor, low in cost, minimal of data loss, and other outstanding advantages. The experiment was done in difference sample of liquids, SRI, and condition. The sensitivity of FBG in air, water, and stingless bee honey were recorded at 10.6892 nm/°C, 10.6247 nm/°C, and 13.3985 nm/°C respectively.It shows that FBG is suit as a temperature sensor in different medium and SRI.

Tapered optical fiber immobilized with glucose oxidase (GOD) has been proposed for glucose recognition. Single mode fiber (SMF) is fabricated by tapering using flame-brushing technique to improve the sensitivity and limit of detection of optical fiber based glucose sensor. Taking the benefits from the free amine groups in 3-aminopropyltriethoxysilane (APTES), the enzyme, GOD are functionalized on the tapered region of SMF through covalent interaction. The pH value of the immobilized enzyme, GOD is the critical parameter for glucose sensing. The lower pH value of buffer solution, which is pH3 shows the highest intensity which is 2949.08 compared with intensity peak of pH5 and pH7 which is 2873.9 and 2700.43 respectively.

Despite considerable research the evidence around the wide applications in the nanomedicine and nanophotonic area of gold-silver (Au–Ag) nanocolloids remains equivocal and under exploration. Due to their physical properties, enhanced permeability, high fluorescent, surface area to volume ratio, retention effect, localized surface plasmon resonance (LSPR) and controlled perfusion of drugs, made Au–Ag nanoparticles is over interested. Hence, we produced Au–Ag nanocolloids using nanosecond pulse laser ablation in liquid (NPLAL) technique. Targets of Au and Ag were submerged individually inside the cubic vessel fulfilled by 8 mL of glycol liquid media and vertically ablated with different pulse laser ablation (PLA) energy (50, 100, 150 and 200 mJ). The influence of the PLA energy (at fundamental wavelength 1064 nm) on the optical properties, morphology, particle size distribution, and chemical structure of the obtained colloidal Au–Au NPs was established. UV-Vis and FTIR spectrophotometers have been utilized to determine the absorbance characteristics and chemical functional groups of Au–Ag nanostructures, respectively. The attained of Au-Ag nanostructure exhibits a single-surface plasmon resonance (SPR) band, positioned between SPR bands of the monometallic and a surface bonding functional group (e.g. carboxyl or hydroxy groups). The proposed technique can be a basis for the developing complex compositions/colloids with unique and optimal physical properties may use for developing future nanomedicinal and nanophotonics.

Owing to the sensing applications, titania nanoparticles (TNPs) are synthesized by sol-gel route at low temperature (80 °C). For pH sensing response, four different pH dyes (phenol red, bromophenol blue, cresol red, and phenolphthalein) mixture is immobilized within TNPs. Thermal and structural behaviour of synthesized TNPs is observed by Thermo-gravimetric analysis (TGA), Fourier transmission infrared spectroscopy (FTIR), and Field emission scanning electron microscopy (FESEM). Thermally stable co-dyes immobilized TNPs confirms void-free surface morphology with heterogeneous chemical bonding. Furthermore, prepared sensing device has linear response with determination coefficient (R2) ∼ 0.97 and sensitivity is calculated as ∼154 I/pH at 431 nm. The response is optimized at pH 11.

Demand for rare earth ions (REIs) doped inorganic glasses have been ever-increasing for diverse photonic applications. Synthesis of these glasses needs the appropriate choice of suitable host matrices, modifiers, and REIs as dopants to improve their spectroscopic traits. In this realization, a new series of magnesium-zinc-sulfophosphate glasses were prepared with varied europium ions (Eu³⁺) doping contents (0 to 2.0 mol%). Such melt-quench synthesized glasses were characterized at room temperature by diverse analytical techniques to determine their physical and optical properties. XRD pattern of as-quenched samples confirmed their amorphous nature. Densities of the glass system were observed to increase from 2.540 to 2.788 g.cm⁻³ with the increase in Eu³⁺ doping contents from 0 to 2.0 mol% which were attributed to the generation of more bridging oxygen atoms and enhanced network compactness. Photoluminescence (PL) emission spectra of glasses exhibited four characteristic peaks positioned at 593, 613, 654 and 701 nm assigned to corresponding ⁵D₀→⁷F₀, ⁵D₀→⁷F₂, ⁵D₀→⁷F₃, and ⁵D₀→⁷F₄ transitions in Eu³⁺, in which the intensity of the peak at 613 nm (red) was highest. Emission intensities of all peaks were enhanced with the rise in Eu³⁺ content up to 1.5 mol% and quenched thereafter. It was affirmed that the physical and optical traits of these glass compositions can be improved by adjusting the Eu³⁺ doping contents. The proposed glass compositions may be potential for the development of varied photonic devices especially for eye safe solid-state red laser and fibre sensors.

We have successfully fabricated and demonstrated a simple, cost-effective and easy to use of fiber Bragg grating (FBG) based on single mode, and multimode fiber which have been employed for temperature monitoring. The study purposely compared the performance of two types of FBGs; single mode FBG (SM-FBG) and multimode FBG (MM-FBG). The FBGs sensor is fabricated by phase mask technique which being exposed to ArF excimer laser with 20 mm uniform grating length and 99% reflectivity. The proposed FBG is studied for temperature monitoring starting at room temperature until 120 °C, and the configurations with SM-FBG and MM-FBG achieved a sensitivity of 10.9 pm/°C and 13.23 pm/°C, respectively whereas linear response correlation coefficient of 0.98229 and 0.99929. These show the MM-FBG has better sensitivity to be used in sensor applications.

In this work, we have successfully fabricated the fiber Bragg grating (FBG) with 1 cm and 3 cm grating length, respectively. The different grating length fabricated by adjusting the slit aperture in order to control UV light transmission while inscribing on the single mode fiber. Then the FBG was demonstrated through different grating length over temperature sensor to determine the differences for temperature sensing. The range for temperature The measured sensitivity of 1 cm and 3 cm grating length is 0.0103 nm/°C and 0.0132 nm/°C respectively at the same value of applied temperature. As a results, the shorter grating length, 1 cm has higher sensitivity response compared to 3 cm grating length over temperature sensing.

A non-adiabatic tapered fiber sensor coated with humidity-sensitive graphene oxide (GO)/Poly (vinyl) alcohol (PVA) nanocomposite film for humidity sensing application was proposed. GO/PVA film was deposited onto the tapered region by dip-coating technique. The surface morphology of the coating film was characterized through Field Emission Scanning Electron Microscope (FESEM). When exposed to percent relative humidity (RH) ranging from 20 to 99.9 % RH, the sensor exhibited sensitivity for both untapered and tapered fibers at −0.00132 ± 0.00043 a. u (%)⁻¹ and 0.00106 ± 0.00008 a. u (%)⁻¹, respectively. The contribution of GO/PVA composite film in enhancing sensor sensitivity was proven, which was 0.00624 ± 0.00033 a. u (%)⁻¹ with percentage of sensitivity boosting up to 15.86 % when compare to the uncoated ones.

The aim of this study is to investigate the volatile organic compound released by stingless bee honey stored at room temperature (≈24°C) for 10 days and how yeast can influence the stingless bee honey quality. A newly harvested stingless bee honey is divided into 8 samples with each containing 100 ml. Each sample is filled into a glass bottle and 8 samples are considered for 8 different days of evaluation. Gas produced by the samples are collected and analyzed using FTIR coupled with White Gas Cell. The spectrum analysis is done by comparing the spectrum of volatile compound with the infrared fingerprint spectral characteristics from Infrared Analysis Inc. database library via Perkin Elmer's spectrum software. Ethanol, methanol, methane, carbon dioxide, water vapour, and ethyl acetate were found to be released by the stingless honey samples. The bands area were identified in order to calculate the concentration of volatile compounds in the honey's gas. The trend of each of the volatile gasses can be seen from Day-1 until Day-8 of evaluation. To study the presence of yeast, 10 g of stingless bee honey is incubated overnight in nutrient broth followed by centrifuging 1.5 ml of the culture broth repeatedly to obtain cell pellet for VPSEM analysis. VPSEM results indicated that morphology of yeast found in the honey sample. Ethanol concentration found to decrease by time however detailed analysis revealed that sample with the presence of yeast shows an increase of ethanol deliberated by the stingless bee honey. This result affirmed that the presence of yeast may facilitate the further alcoholic fermentation in stingless bee honey by which affecting the sensory value of the stingless bee honey.

In the modernized era, the air conditioners are an integrated part of comfort living especially in hot climates. They are used to control the interior spatial temperature, relative humidity, degree of cleanliness, and speed of air streaming. The automatic controllers are the key elements of the modern air conditioning systems that ensure the reliable operation, improved quality, low operation cost, and better security. Thus, the realization, design, and application of the controller systems require the exact specifications of the involved processes. In this regard, controllers based on the fuzzy logic (FL) are prospective for air conditioners due to the easy accessibility of different output levels. Furthermore, using the FL it is possible to scale and control the users' air processing demand depending on the temperature and relative humidity of the space. Based on these factors, this paper reports the design and performance evaluation of a FL based controller useful for air conditioners when implemented in the classroom setting. This FL based control system can reduce the complexity of programming thereby can be executed on general microcontrollers utilized in the control panels of classroom air conditioner. The results revealed the outperforming nature of the FL based controllers over other traditional controllers used to adjust the indoor temperature and relative humidity by air conditioners.

Achieving highly efficient visible red emission with high color purity from the rare earth ions doped glasses containing metallic nanoparticles is of scholastic significance in the quest of novel laser glass host. Stimulated by this demand, we synthesized some new class of silver nanoparticles (Ag – NPs) embedded europium ions (Eu³⁺) doped boro – telluro – dolomite glasses (hereafter coded as BTDEAx, where x = 0.0, 0.1, 0.3, 0.5, 0.8 and 1.0 mol%) by convectional melt quenching method. These glasses were optically characterized using UV – Vis – NIR absorption and photoluminescence (PL) spectroscopy's to ascertain their lasing candidacy. The absorption spectra of the Eu³⁺ ion free sample (BTDA0.8) disclosed a single surface plasmon band characteristic of Ag – NPs at 464 nm. Meanwhile, the visible emission intensities (excited with 467 nm wavelength) of the glasses due to Ag – NPs inclusion were greatly intensified. Of all glasses, the sample prepared with 0.8 mol% of Ag NPs (BTDEAg0.8) revealed highest PL intensity enhancement. Furthermore, the attainment of high color purity (97.037 %) detected from the CIE diagram with chromaticity coordinates (0.63765, 0.36094) close to ideal red color phosphor (0.67, 0.33) indeed approved the suitability of the proposed glasses for solid state red laser construction.

Optical fibre sensor (optrode) depending on a transmittance was presented as a valuable sensitive sensor for several applications. Thus, the development of a wide-area detection system for continuously monitoring structural changes, together with a capability for non-destructive evaluation and early warning, is an important task the sensitive fibre was preparing by removing the cladding from several places and modified by different chemical solutions. The transmittance spectrum used to measure the pH of distilled water that contains HCL and NaOH in a range between 2 to 12. The special design of this sensor made it a perfect for laboratory and industrial usage, only 25 cm of modified fibre was enough to measure the pH in real time with a sensitivity 0.015-0.2 1/pH. The results showed this sensor can work in different solutions and it gives accurate results at any conditions.

Tapered optical fiber (TOF) sensor based on localized surface plasmon resonance is demonstrated for refractive index sensing application. The single-mode fiber (G652D) with 10/125 µm of core/core-cladding diameter was tapered by flame brushing method and achieved a waist diameter of approximately 15µm. Mercapto group (-SH) of 3-mercatoptopropyltrimethoxysilane (MPTMS) was utilized for immobilization of gold nanoparticles (AuNPs) by self-assemble monolayer (SAM) method on fiber surface. Evanescent field at the TOF sensing region excites the localized surface plasmons of AuNPs, with average mean diameter 15 ± 2 nm as evidence by scanning electron microscopy (SEM). The effect on deposition time was examined on three different samples; S1, S2 and S3 with 24h, 48h and 72h of coating time respectively. TOF sensor performance was evaluated with surrounding refractive indices ranges from 1.3324 to 1.4254. The sensing mechanism is based on the modulation of output light signal that represent by transmission shifting spectra. The optimum sensitivity was obtained for S2 at 18 nm/RIU with good repeatability, reversibility and stability.

Electron Swarm Parameters in plasma gas mixtures of Co₂ have been calculated. Studies focused on four gas mixtures with Co₂, He, and N₂ in the ratio 5%: 55%: 40%, 2.5%: 45%: 52.5%, 10%: 50%: 40% and 40%: 40%: 20% respectively. Calculations of the electron energy distribution function f (ε), drift velocity V_d, mobility μ, electron diffusion D, D/μ, electron average energy <ε> and electric field E in the range of electric field to gas number density ratio E/N from 1×10⁻¹⁹ to 5×10⁻¹⁵ at 300 ⁰K were reported in this work. The theoretical calculations shown helium has a good effect on the electrons transition parameters of Co₂ laser. Furthermore, at low energy, the total collision rate is increasing slowly for higher electron energy.

In this research, the simulation of lateral distribution function (LDF) of Cherenkov radiation was performed using CORSIKA software for two hadronic models QGSJET and GHEISHA. This simulation was performed for several elementary particles such as protons, iron nuclei, electrons and gamma quanta, in the range of energies 1-20 PeV for three zenith angles 0°, 20° and 30°. A parameterization of Cherenkov light LDF was performed for that simulated curves using Lorentzian function. The comparison between the obtained results for LDF of Cherenkov light with that measured with Yakutsk EAS array gave a good agreement within the distances of 100-1000 m from the shower axis.

The simulation of the extensive air showers was performed by investigating the longitudinal development parameters (N and Xmax) by using AIRES system version 19.04.0. The simulation was performed at the energy range (10¹⁸-10²⁰ eV) for different primary particles (such as primary proton and iron nuclei) and different zenith angles. The longitudinal development curves of EAS are fitted using Gaussian function that gave a new parameters for different primary particles and different zenith angles at the energy range (10¹⁸-10²⁰ eV). The comparison between the obtained results, the parameterized longitudinal development using Gaussian function that gave a new parameters for different primary particles with the experimental measurements (AUGER experiment) that gave a good agreement for primary proton and iron nuclei at the energy 10¹⁹ eV for θ = 0˚.

We have successfully generated a Q-switched ytterbium-doped fiber laser pulses using few layers of Molybdenum Selenide (MoSe₂) as saturable absorber (SA). The setup was a ring fiber laser cavity with few-layer MoSe₂, deposited onto a fiber ferrule using an optical deposition technique. A stable pulses started at input power of 68.8 mW with repetition rate ranging from 14.2 kHz to 34.0 kHz was achieved with highest pulse energy, shortest pulse width and highest output power of 3.6 nJ, 4.4 µs and 0.12 mW were observed, respectively.

We have demonstrated an ultrafast mode-locked pulses generation by sandwiching graphene thin film between fiber ferrules in a simple erbium-doped fiber laser (EDFL) ring cavity setup. The incorporation of graphene thin film acted as a saturable absorber (SA) and had generated a stable mode locked pulse with repetition rate of 8.3 MHz, narrowest pulse duration of 1.38 picoseconds and 1558.8 nm wavelength.

Five-layer slab a waveguide combined with a metamaterial has been studied. The central layers were the metamaterial and a normal material in the core of waveguide. The dispersion relation, field formulas, power formulas and the power flux formula has been derived. The waveguide property was controlled by changing the permittivity and permeability and thicknesses of the layers. The presence of metamaterial contributes to cut-off the mode TE_o and other modes were propagated to backward. The stopping light was determined using the power flux value. However, the negative values of it refer to the backward direction of propagation. Furthermore the stopped light can be achieved in a certain value of power. Our results found it is good for different applications in communication and controlling.

In this work, the influence of samples temperature and laser energy on the optical emission spectra and plasma parameters of laser-induced breakdown spectroscopy for aluminum and copper metallic target is investigated. The samples are uniformly cooled down to −70 °C and heated up to 200 °C by an external liquid nitrogen and ceramic heater, respectively. The plasma formed is generated by ablating the surface targets using Nd:YAG laser with laser energies of 100 mJ, 200 mJ and 300 mJ. The emission spectra at ambient atmospheric pressure are recorded using HR4000 spectrometer. From these spectra, plasma temperatures and electron densities are determined by using Boltzmann plot and Stark broadening methods, respectively. A significant increase in the peak intensity of spectral lines is observed with increase in the laser energy as well as sample temperature for both elements. Both of these parameters have shown a clear influence on dynamics of laser-induced plasma for each species. In brief, both laser energy and sample temperature affect the emission intensity, temperature and density of the laser-induced plasma generated from aluminum and copper samples.

In this paper, the effect of Nd:YAG laser wavelength and energy on the synthesis of gold nanoparticles is reported. Gold nanoparticles colloidal solutions were prepared by pulsed laser ablation of gold target in deionized water. The Nd:YAG laser with repetition rate of 1 Hz was assigned to supply energy at fundamental and second harmonic wavelengths i.e., 1064 nm and 532 nm, respectively. Synthesized nanoparticles were characterized using particle size analyzer (PSA). Four different laser energies were used to ablate the samples and synthesize gold nanoparticles. The average size of gold nanoparticles was found to decrease with increasing laser energy. The gold nanoparticles of smaller size were obtained when the target was ablated with 532nm wavelength of Nd:YAG laser. Higher laser energies and efficient absorption of 532 nm wavelength resulted in size reduction by fragmentation of colloidal nanoparticles.