BiF3 nanoparticles doped with Yb3+ and Er3+ ions in varying ratios were prepared by co-precipitation method and its upconversion luminescence (UCL) properties were investigated in detail before and after high-intensity laser treatment. Green-to-red ratio (GRR) of luminescence from cubic-BiF3:Yb,Er nanoparticles is found to increase with an increase in laser power for as prepared sample. Unlike this, for conventional Yb,Er doped upconversion nanoparticles (UCNPs) such as cubic NaYF4:Yb,Er and hexagonal-NaYF4:Yb,Er, a decrease in GRR values is observed with an increase in laser power. This has been explained based on the reduced extent of Er3+-Er3+ interaction in BiF3:Yb,Er nanoparticles compared to that existing in cubic and hexagonal forms of NaYF4:Yb,Er, nanoparticles. Reduced interaction is brought about by higher lattice parameter of BiF3 host compared to the NaYF4 host which leads to a lesser extent of cross-relaxation in the former host thereby favoring the population of 4S3/2 and 2H11/2 levels of Er3+. Effect of high-intensity laser (180W/cm2) irradiation on BiF3:Yb,Er nanoparticles resulted in an irreversible five-fold increase in upconversion luminescence intensity and this is attributed to combined effect of partial conversion of BiF3 to cubic Bi2O3 and removal of adsorbed water molecules. These inferences are confirmed by XRD and TEM measurements carried out on laser-treated sample. Improved luminescence intensity from the laser-treated sample is also confirmed by the high-contrast clear images obtained from impressions made using high-intensity laser irradiation on BiF3:Yb,Er nanoparticles. BiF3:Yb,Er nanoparticles showed an excellent thermal sensitivity of 0.3% K−1 at room temperature and the value is comparable with that of conventional β-NaYF4:Yb,Er nanoparticles.

Lab-grown diamond films, vital for advanced electronics and biomedical applications, pose production challenges. This study investigates a simplified method to create fluorescent diamond films and assesses their potential as temperature sensors. Polycrystalline diamond (PCD) films functionalized with NaYF4:Er,Yb upconversion nanoparticles (UCNPs) have been developed, and their temperature sensitivity of luminescence has been evaluated. UCNPs functionalized on surface-treated PCD films (UCNPs-TPCD) exhibit superior temperature sensitivity (S r = 1.08% at 300 K-1) compared with the as-prepared UCNPs and UCNPs coated on the as-grown PCD films (UCNPs-PCD). Surface oxidation of PCD films facilitates uniform UCNP distribution, verified through upconversion luminescence, XPS, IR, and Raman spectroscopy alongside SEM and AFM. An increase in the temperature of the diamond lattice due to 980 nm laser irradiation leads to an increase in the population of the 2H11/2 level of Er3+ and the associated increase in the fluorescence intensity ratio and improved temperature sensitivity of UCNPs functionalized on the treated diamond surface. Hysteresis in luminescence is observed for the first time in PCD films functionalized with UCNPs, attributed to an increased temperature from the absorption of 980 nm light by diamond films.

Engineering a single phosphor for multiple objectives is challenging and essential for innovative technology, enriching productivity and flexibility, lowering cost, minimizing power intake, etc. In this study, a Yb3+,Er3+-activated NaBiF4 nanophosphor synthesized via a thermolysis approach provided significant opportunity to explore the potential of single phosphor in diverse fields including contactless thermometry, plasmon-enhanced upconversion luminescence (UCL), solid-state lighting, and photoswitching probes. The phosphor has been characterized using several standard techniques to unveil the phase, crystal structure, associated functional groups, morphology, crystalline nature, and optical properties. A 5-fold enhancement in UCL intensity was observed from Yb3+,Er3+:NaBiF4@SiO2@Ag. Upconversion luminescence thermometry of Yb3+,Er3+:NaBiF4 based on thermally coupled energy levels (TCELs) 2H11/2 and 4S3/2 was studied via the fluorescence intensity ratio (FIR) technique. Thermometric parameters based on the ratio of Er3+ transitions (2H11/2 -> 4I15/2 and 4S3/2 -> 4I15/2) results in ln I 520/I 540 = 3.88-1086.83/T and Delta E similar to 755.34 cm-1. Results revealed Delta T = 0.4 K at 297 K, and maximum relative sensitivity (S r) and absolute sensitivity (S a) values are 1.23% K-1 (at 297K) and 0.173% K-1 (at 397K), respectively. The energy transfer and thermal quenching process were demonstrated mechanistically. The Commission Internationale de l'Eclairage (CIE) chromaticity diagram confirms the suitability of this material as a green light emitter. The unprecedented photostability and photoswitching behavior has been addressed by a photoelectrochemical cell experiment under light and dark conditions. Results suggest that Yb3+,Er3+-activated NaBiF4 is the most promising high-quality luminescent nanophosphor, reflecting the realm of scientific evolution and providing applications in luminescent thermometers, plasmon-enhanced UC luminescence, solid-state lighting, and fast switching photodetectors.

Non-lanthanide based NaBiF4 host have evoked remarkable interest due to unique luminescent property and potential applications. Current synthetic methods are not environment friendly and causes pollution. This is the first report mentioning green synthetic innovative route to develop upconversion, crystalline, and temperature sensing material. Here, we deigned ultrasonic assisted green approach for successful synthesis of beta-NaBiF4:Yb3+, Er3+ (size -25-100 nm) using Tabernaemontana divaricata leaves extract without any surfactant. Characterization techniques such as XRD, SEM, TEM, XPS, EDX, and PL unveiled its properties. Green and red upconversion emissions (lambda ex = 980 nm) were two-photon absorption process. The possible energy transfer and thermal quenching mechanism is discussed. Using thermally coupled levels (2H11/2 and 4S3/2) of Er3+, FIR based temperature sensing revealed Delta E -841 cm -1, linear response (R2 -0.99), outstanding relative sensitivity (Sr max similar to 1.4 % K-1 @294 K), good absolute sensitivity (Sa max similar to 0.29 %K-1 @ 398 K) and a low temperature resolution (delta Tmin = 0.35 K) over temperature range 294-398 K.

A two-dimensional electrostatic particle-in-cell code is developed with an adaptive mesh feature to investigate the dynamics of photoplasma in M-type electrode configurations. This adaptive mesh is designed by using a one-dimensional pseudo mesh, where at the starting of each pseudo cell the quasineutrality and density of charged particles are checked, which decides the coarseness of the actual computational mesh. Through this developed particle-in-cell code, the ion extraction process from a finite-size photoplasma is simulated for parallel plate and M-type electrode configurations. Subsequently, the ion extraction time from the photoplasma is investigated by using the different potential waveforms, i.e. constant and two-step potential. On the basis of this numerical hypothesis, it is observed that the efficacy of M-type configuration is better than the parallel plate electrode configuration. Moreover, ion collection efficiency is also improved using a two-step potential waveform.

The ion extraction from laser-induced photoplasma in an electrostatic field is investigated by a 2.5-D-electrostatic particle-in-cell (PIC) code. The external electrostatic field is applied by a plate–grid–grid–plate (PGGP) electrode configuration. In this configuration, two additional grids are introduced in a parallel plate electrode configuration. Basically, these grids are kept at more negative potential than the cathode, and therefore, the grid extracts the ion, whereas plates collect the ions. Through such biasing, the sputtering of the already collected ions on the collecting plate can be avoided. The present investigation emphasizes on spatiotemporal evolution of photoplasma in the PGGP electrode configuration. Subsequently, investigate the performance of this electrode configuration with different biasing of electric potential. Finally, it compares the performance of PGGP with parallel plate and M-type electrode configurations. Based on this comparative analysis, an improved design of the PGGP electrode configuration is suggested. In addition, it also explains modeling aspects of different electrode geometries using 2.5-D-PIC, which includes the boundary conditions for Poisson’s equation, particle boundary conditions, and grid designing.

The ion-extraction process from a finite-size photoplasma is simulated by using a two-dimensional electrostatic particle-in-cell code. To investigate the impact of different electrode configurations on the ion extraction process the parallel plate, wire-type, II-type, and M-type electrode configurations are used. The present study compares the ion extraction time of these electrodes and provides a quantitative audit of the photoions. Through this, it is observed that the M-type electrode configuration extracts more ions in less time than the other electrode configurations. Subsequently, this study quantifies the ion collection on different electrodes, which can be further utilized to design the electrode configuration. Moreover, it gives a systematic study of the ion extraction process in an electrostatic field with different electrode configurations.

Water is being considered as an economical, safe and environmental friendly alternative solvent for dye lasers. However, the use of water in dye laser is restricted due to the formation of non-emissive aggregates of dye molecules. In the present study we have explored the possibility of the use of commercially available surfactant molecules for the water based laser of Pyrromethene 597 (PM597) dye, which has emerged as an alternative for more commonly used Rhodamine dyes in dye laser systems. Our studies show that in water, PM597 forms non-emissive aggregates which can be dissociated into monomeric dye molecules by adding common surfactants. Further, the high microviscosity in the micellar media retarded energy wasting ring puckering process in the excited state of the dye leading to the increase in its emission yield and excited state lifetime to a significant extent. It has been demonstrated that the emission yield and excited state lifetime in surfactant solution is relatively higher than in ethanol, the most commonly used organic solvent for dye lasers. Lasing action has been demonstrated in the aqueous solution of dye and lasing efficiency is found to be comparable to ethanol.

This paper describes a detailed theoretical analysis of the ionization lineshape based on numerical integration of coupled differential equations of motion for an optical double-resonance (ODR) ionization scheme. The results of the optimization studies, to identify laser intensities of both the excitation steps for efficient and selective ionization of Yb-168 isotope are presented. The evaluated saturation intensities are found to agree well with earlier reported experimental results. Quantitative estimation of interference of the neighboring isotopes on the selective ionization is carried out by taking into account the finite laser bandwidths. The dependence of Autler-Townes doublet peaks of neighbouring isotopes on the spectral bandwidth of the excitation lasers and their consequent influence on the ionization lineshape is discussed elaborately. The studies indicate that accurate and quantitative prediction of the selectivity and ionization efficiency is feasible by inclusion of realistic experimental conditions. The theoretical results indicate that the degree of enrichment of 91 is feasible for the low abundant Yb-168 isotope with an ionization efficiency of <= 32%. (C) 2021 Elsevier Ltd. All rights reserved.

In this article, a 1-D electrostatic particle-in-cell (PIC) code is developed in an object-oriented paradigm with a computationally improved Poisson Solver. The performance of a Poisson solver plays a vital role in the computational cost of an electrostatic PIC. Therefore, to reduce the overall cost of the system, the Gauss–Seidel with a modified Chebyshev acceleration scheme is implemented as a Poisson solver. This method is designed by altering the standard Chebyshev acceleration scheme and executed with the optimal spectral radius. A separate program is written to optimize the spectral radius and to investigate its impact on the rate of convergence. Subsequently, a comparative analysis of this solver with the Gauss–Seidel, Gauss–Seidel with successive over-relaxation, and Gauss–Seidel with the Chebyshev acceleration factor is carried out, which implies that the modified solver converges fast. This article also provides the object-oriented architecture, including some key features of C++. The developed code is benchmarked with the two-stream instability, which evolved self-consistently. The performance of the overall code is evaluated by considering up to two million particles on two different CPUs and it is observed that the standard CPU is capable to solve the 1-D PIC problem. This code is implemented to study various characteristics of a finite-size photoplasma like plasma sheath formation, ion phase response, and electron dynamics when it is subjected to a uniform electric field.

Plasma is the fourth state of matter. Broadly, it can be classified into two categories first one is natural occurring plasma and another one is laboratory plasma. Laboratory plasma has variety of application in the field of material synthesis, controlled fusion, thruster, plasma-based lighting and display systems. In this paper an exhaustive literature survey on generation of laboratory plasma is provided. The objective of this paper is to provide an overview of various plasma generation methods that include plasma generation using electrical fields, electron beams and laser beams.

Gain extraction dynamics of co amplification of multi signal amplification in a pulsed dye amplifier is theoretically studied using four level rate equations. Generic multi signal amplification in dye gain media and gain competition among amplifying signals were studied for two gain media of rhodamine 6 G and DCM laser dyes. Wavelength and power depended gain competition of one signal on other co amplifying signals for dual and three wave amplifiers were evaluated. This study will be useful for implementing compact multi wavelength oscillator and amplifier system.

Characteristics of an efficient spectral beam combination of two dye laser beams with wavelength difference of less than 10 nm are presented. Two dye laser oscillator beams were spatially and temporally combined with reduced losses before their co-amplification in a common power amplifier. Yellow and green beams of 9 kHz (pulse repetition rate) copper vapour laser (CVL) Master Oscillator Power Amplifier (MOPA) Chain were utilised to pump Rh 101 dye laser oscillators and DCM dye common amplifier respectively. The characteristics of green beam pumped DCM dye common amplifier were studied at various pump power and input power ratios. Combination losses for this configuration were 40% relative to individually amplified configuration. Input-output characteristics of the common amplifier were determined at various input power ratios. Composite dual wavelength dye laser beam having total power of 7.35W at 38.4 W pump power with extraction efficiency 16.5% was demonstrated.

In this study, Bi3+ incorporation in NaYbF4 :Er lattice and its influence on upconversion luminescence properties have been investigated in detail using techniques such as temperature-dependent luminescence, Fourier transform infrared spectroscopy and X-ray diffraction (XRD). The study was carried out to develop phosphors with improved upconversion luminescence. From photoluminescence and lifetime measurements it is inferred that luminescence intensity from NaYbF4 :Er increases with Bi3+ addition. The sample containing 50 at.% Bi3+ ions exhibited optimum upconversion luminescence. Increased distance between Yb3+ -Yb3+ and Er3+ -Er3+ due to Bi3+ incorporation into the lattice and associated decrease in the extent of dipolar interaction/self-quenching are responsible for increase in lifetime values and luminescence intensities from Er3+ ions. Incorporation of Bi3+ into NaYbF4 :Er lattice reduced self-quenching among Yb3+ -Yb3+ ions and this facilitated energy transfer from Yb3+ to Er3+ . This situation also explains decrease in the extent of temperature-assisted quenching of emission from thermally coupled 2 H11/2 and 4 S3/2 levels of Er3+ . Based on Rietveld refinement of XRD patterns it was confirmed that a maximum of 10 at.% of Bi3+ added was incorporated into the NaYbF4 :Er lattice and the remaining complex co-exists as a BiOF phase. These results are of significant interest in the area of development of phosphors based on Yb3+ -Er3+ upconversion luminescence.

Although aqueous dye lasers are much sought after, they have been of no practical use, as laser dyes show a strong tendency for aggregation in water, thus diminishing their optical output. Contributing towards this shortcoming, we studied the noncovalent interactions of two prominent laser dyes, namely, rhodamine 6G and rhodamine B, with a water soluble macrocyclic host, sulfobutylether-β-cyclodextrin (SBE7 βCD). Spectral changes in the absorption and fluorescence behavior of dyes in presence of the SBE7 βCD host indicated adequate complex formation between dye and host (K∼104  M-1 ). A combination of various photophysical parameters evaluated from measurements such as Job plot, changes in the fluorescence lifetime/anisotropy values, and favorable thermodynamic parameters from isothermal titration calorimetric measurements adjudicated a 1 : 1 stoichiometric complex formation between dye and SBE7 βCD host. Consequently, SBE7 βCD prevents dye aggregation/adsorption and present rhodamine dyes in their monomeric forms with enhanced fluorescence yield and brightness. These vital parameters were utilized to optimize and demonstrate cost-effective supramolecular broad-band and narrow-band aqueous dye laser systems with improved lasing efficiencies (∼25 % higher for the SBE7 βCD : RhB system and ∼10 % higher for SBE7 βCD : Rh6G system), better beam profile, and enhanced durability compared to the respective dyes in optically matched ethanol solutions.

The thermo optic coefficient for the commonly used dye solvents such as ethanol, demineralized water and their mixtures has been measured using a simple interferometric technique. A Michelson interferometer based sensor measures the change in the optical path length due to increased solvent temperature in one of the arm length of interferometer. The temperature coefficient of refractive index for ethanol has been obtained from the change of the wavelength of single mode dye laser with solvent temperature. The value of the thermo optical coefficient for ethanol obtained by two methods is matched. The aim of this study is to measure the thermo optic constant of the commonly used dye solvent for the high repetition rate pulsed dye lasers.

Characteristics of a multi wavelength dye laser in two cascaded grating resonator configurations are presented. DCM dye dissolved in ethanol, was transversely pumped by second harmonic of Nd:YAG laser and four wavelength, independently tunable, collinear dye laser operation was obtained in Cascaded Grazing Incidence Grating cavity (CGIG) and Hybrid CGIG with fourth grating in Littrow angle (HCGIG) configuration. Gain competition effect of all the sub-cavities was fully characterized and wavelength zones of operation were identified for each cavity for sustaining four wavelength operation. Overall efficiency of the oscillator was measured to be around 2% in CGIG and 7% in HCGIG.

An efficient fiber optic based high average power pulsed laser beam delivery system was developed for dye laser pumping. A novel fiber coupling technique was designed for minimizing thermal damage at the fiber ends along with reduction in Fresnel losses.

Spectrally stable dye lasers play an important role in techniques based on high resolution spectroscopy and atomic spectroscopy. The spectral purity of a dye laser is affected when the pump power to it is increased beyond the threshold. When the pump power is increased beyond the threshold, two mode oscillations occur which decrease the spectral purity of the dye laser. The effect of higher pump pulse energies on transient thermal effects has been studied using a computational fluid dynamics (CFD) model and the disturbances to the laser cavity have been studied using commercially available ray tracing software. The change in the cavity length was determined from the CFD model for several dye concentrations and pump powers. The results of the CFD model have been verified by published results and experimental results from our system. Our study shows that in the longitudinally pumped single mode laser change in the cavity length is a more dominant disturbance than thermal blooming. Our model is useful for the design of the dye cell.

A simple technique had been demonstrated for measuring flow-induced fluctuations in the single longitudinal mode (SLM) pulsed dye laser. Two prominent frequency components of 10.74 Hz and 48.83 Hz were present in the output of the Nd:YAG-pumped SLM dye laser. The flow-induced frequency component of 48.83 Hz was present due to the revolution per minute of the motor attached to the magnetically coupled gear pump. The time average bandwidth of 180 MHz has been obtained for this SLM dye laser. The effect of pump pulse energy on the bandwidth of the SLM dye laser was studied. The bandwidth of the SLM dye laser was increased to 285 MHz from 180 MHz, when the pump pulse energy was increased to 0.75 mJ from 0.15 mJ for a constant dye flow velocity of 0.5 m/s.