Guided Wave Resonant Optical Structures and LED Micro Resonators for Biosensing Applications

Integrated opto-electronic and nanophotonic devices for sensing application in the fields of medicine, microbiology, environmental, safety and defense have attracted considerable attention due to their potential for achieving greater compactness, shorter response times and higher sensitivities as compared to non-optical sensing systems. Optical cavity resonant devices such as Fabry--Perot interferometers have been extensively used in lasing applications and optical sensing has been accomplished through many similar technologies.;Fiber optic and planar waveguide based resonant devices which use evanescent waves for detection of refractive index changes are one of the most widely used approaches for photonic sensors. In this work we investigate the simulations, fabrication and characterization of resonant optical cavity devices for sensing applications. Morphology Dependent Resonances (MDRs) of planar, micro-spherical and micro-cylindrical cavities were reviewed for resonance line widths, spacing between modes, and density of resonances and experimental observations of internal and external field distributions. We focus on planar thin film stacked resonant waveguide geometries, microsphere-waveguide coupled resonances, cylindrical Gallium Nitride (GaN) microdisks for passive detection of Whispering Gallery Modes (WGMs) and electrically pumped active Resonant Cavity (RC) LED disk geometries for Vertical Cavity Modes (VCMs) as structures of interest.;Advances in stacked thin film coupled waveguide sensors enhance the selectivity and sensitivity by measuring the changes of the resonant optical modes and provide an integrated platform for label-free molecular detection. The effective surface loading detection sensitivity of the planar coupled alumina waveguide transducer was determined to be 20 pg/mm2 with a bulk index sensitivity of 5.6x10-4 Refractive Index Units (RIU) for aqueous sucrose solutions. For circular geometry based resonators, as the physical device size approaches the wavelength of light the MDRs are enhanced by retaining longer photon path length times and enhancing detection due to its high Q factors. Circular micro-cavities not only modify the optical resonances but also distribute the resonant frequencies as compared to a planar macro-cavity. The waveguide-coupled microspheres were experimentally detected to have a minimum surface coverage limit of 0.192%. Passive WGMs in GaN micro-disks showed a variation in mode spacing of 3nm to 7nm (lambda2/2piRn) as disk radius was reduced from 4.5microm to 2microm. Micro-cylindrical Distributed Bragg Reflector (DBR) RCLEDs were designed for layer thicknesses and Multi Quantum Well (MQW) placement to enhance VCMs and LED emission output. Experimental and simulated LED spectral minima matched at 432 nm and 451 nm confirming VCMs related to (lambda/2) cavity resonances

Flowy: High performance probabilistic lava emplacement prediction

Lava emplacement is a complex physical phenomenon, affected by several factors. These include, but are not limited to features of the terrain, the lava settling process, the effusion rate or total erupted volume, and the probability of effusion from different locations. One method, which has been successfully employed to predict lava flow emplacement and forecast the inundated area and final lava thickness, is the MrLavaLoba method from Vitturi et al. The MrLavaLoba method has been implemented in their code of the same name. Here, we introduce Flowy, a new computational tool that implements the MrLavaLoba method in a more efficient manner. New fast algorithms have been incorporated for all performance critical code paths, resulting in a complete overhaul of the implementation. When compared to the MrLavaLoba code, Flowy exhibits a significant reduction in runtime -- between 100 to 400 times faster -- depending on the specific input parameters. The accuracy and the probabilistic convergence of the model outputs are not compromised, maintaining high fidelity in generating possible lava flow paths and deposition characteristics. We have validated Flowy's performance and reliability through comprehensive unit-testing and a real-world eruption scenario. The source code is freely available on GitHub, facilitating transparency, reproducibility and collaboration within the geoscientific community

Experimental and Numerical Analysis of Variable-density Flow and Transport Scenarios

Saltwater contamination has received a lot of attention in the past few years with natural disasters such as tsunamis and hurricanes causing widespread groundwater pollution. Groundwater modeling of saline contaminant plumes is complex due to the underlying density effects. The research presented here aims to improve the understanding of variable-density processes under both laboratory and field conditions. New benchmarking datasets were developed for saltwater intrusion (saltwedge) scenarios under controlled laboratory conditions. Three types of datasets- steady-state, transient and flux- were presented for the purpose of verifying the numerical codes. Results from SEAWAT, a widely used variable-density model, were tested against the acquired datasets and shown to match the experimental results. Other variable-density models (SUTRA, SWI) were also tested against the proposed datasets and produced close matches. Image analysis procedure was used to measure the spatial concentration profiles in the experimental tanks during variable-density experiments. A detailed error analysis method was developed to estimate accuracy in the application of image analysis procedure. Also, the proposed error estimation method was shown to be better than the often used methods available in literature. The image analysis procedure was improved based on the results from the analysis and a more accurate concentration dataset was obtained using the improved procedure. Variable-density experiments were conducted to obtain datasets with and without instabilities. The datasets were then modeled using SEAWAT with different numerical parameters. It was shown that MOC (method of characteristics), TVD (total variation diminishing) and regular finite difference methods are not suitable to be used for modeling variable-density scenarios when instabilities can develop as they lead to wrong predictions. Finite difference in conjunction with heterogeneity was found to be the best method. Variable-density flow and transport theory was applied to study two different phenomenon- a) migration of zero-valent iron nanoparticles (ZVI); and b) fate and transport of saltwater trapped in open wells after a saltwater contamination event such as a tsunami or a hurricane

Two dimensional effects of laser interacting with magnetized plasma

Recent advancements in low-frequency short-pulse $CO_2$ lasers and the production of strong magnetic fields have made experimental studies on laser interactions with magnetized plasma a near-future possibility. Therefore, theoretical and numerical simulation studies have been pursued lately in this direction [A. Das, Review of Modern Plasma Physics 4, 1 (2020)] illustrating a host of novel phenomena related to laser energy absorption [Vashistha et al., New Journal of Physics, 22(6):063023 (2020); Goswami et al., Plasma Physics and Controlled Fusion 63, 115003 (2021)], harmonic generation [Maity et al., Journal of Plasma Physics, 87(5) (2021)], etc. However, most of these studies have been carried out in one-dimensional geometry with the laser having infinite transverse extent, and the plasma target was considered cold. This manuscript explores the manifestation of the 2-D and thermal effects on the problem of a laser interacting with magnetized plasma. As expected, additional transverse ponderomotive force is shown to be operative. A finite temperature of the target, along with transverse density stratification generates, leads to diamagnetic drift for the two plasma species. The imbalance of this drift between the two species can be an additional effect leading to an enhancement of laser energy absorption. The Particle - In - Cell (PIC) simulations with the OSIRIS4.0 platform is used to explore these features.Comment: 15 pages, 12 figures, 12 equation

Harmonic generation in magnetized plasma for Electromagnetic wave propagating parallel to external magnetic field

The harmonic generation has always been of fundamental interest in studying the nonlinear nature of any physical system. In the present study, Particle - In - Cell (PIC) simulations have been carried out to explore the harmonic generation of Electromagnetic waves in a magnetized plasma. The EM wave propagation is chosen to be parallel to the applied external magnetic field. The simulations show the excitation of odd higher harmonics of RCP (Right circularly polarized) and LCP (Left circularly polarized) when the incident wave is linearly polarised. The harmonic generation is maximum when the incident EM wave frequency matches the electron cyclotron frequency. When the incident EM wave has a circular polarization, no harmonics get excited. A theoretical understanding of these observations has also been provided. The studies thus show that by appropriately tailoring of plasma parameters EM waves of higher frequencies and desired nature of circular polarization can be generated.Comment: 25 pages, 15 figure

Ion heating in Laser interacting with magnetized plasma

The ion heating mechanism in the context of laser interacting with plasma immersed in a strong magnetic field is studied. The magnetic field is chosen to be strong for laser electromagnetic field propagation inside the plasma to be governed by the magnetized dispersion relation. Both X and RL mode configurations have been studied in detail using Particle - In - Cell (PIC) simulations. It is shown that the energy absorption process is governed by a resonant mechanism wherein the laser frequency matches with an underlying mode in the plasma. For X and RL mode configurations, these correspond to lower hybrid and ion cyclotron resonance, respectively. The absorption, however, is found to be most efficient at frequencies close to but not exactly matching with the resonance frequency. An understanding of the same has been provided. The role of laser polarization has been studied in detail.Comment: 21 pages, 17 figure

ADOPTING INNOVATIVE METHOD AND COMPARATIVE EVALUATION OF SWETHA PARPATI MENTIONED IN AYURVEDIC LITERATURE

In Ayurveda, the study of the therapeutic uses and effects of drugs means Pharmaco-therapeutic is described under the branch of Rasashastra which mainly incorporates inorganic, herbo-mineral and metallic pharmaceutical preparations namely Khalviya Rasayana, Parpati Rasayana, Pottali Rasayana and Kupipakwa Rasayana. This article aims for the comparative assessment of Swethaparpati coming under Parpatikalpa mentioned as per reference of Sidhayogasangraha, AFI with another reference of Rasodharatantra. According to the first two references the ingredients used for the preparation are Suryakshara, Sphatika and Navasadara and as per the third reference ingredients like Tankana and Karpura are added. Here a detailed review of literature has been collected regarding the potential of the above mentioned individual ingredients along with the recent research updates regarding individual ingredients used in the production of Swetha Parpati according to both the references it also incorporate research updates on the formulation Swetha Parpati. This article also aims pharmaceutical standardization of standard method adopted in process of production of Swethaparpati with the alteration made from the usual method adopted in preparation of Parpati Kalpana that will help for developing new improved SOP regarding the formulation. This paper also aims in projecting the improved therapeutic value which could be generated by addition of new ingredients mentioned as per reference of Rasodharatantra

A CRITICAL AYURVEDIC LITERARY REVIEW OF THE PLANT PANASA (ARTOCARPUS HETEROPHYLLUS LAM.)

Panasa (Artocarpus heterophyllus Lam), the well known jackfruit tree is widely distributed all over the world. It is a treasure trove of various ethnomedical uses which are yet to be proven scientifically. Its fruit is very delicious and its leaves, root, latex, seed and wood are reported to have many medicinal properties. Though the plant is renowned for its nutritive values, the useful parts of the plant with rich medicinal values are less utilized for medicinal purposes. The plant is well described in Ayurvedic classics where prime importance has been given to its fruit whereas least references are available concerned to its other useful parts especially the leaf. This forms the literature gap concerned with this drug that hinders its further clinical researches. A compiled review of the classical literature of Panasa is not yet available as a ready reference. Hence it is a herculean task for the researcher to compile the literature which is scattered in various classical books of different era. In this work focus has been made to compile the literature of the plant Panasa (Artocarpus heterophyllus Lam) from the Ayurvedic classics. As this work provides the literature of this plant under a single roof it will be helpful for the scholars in future research works