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Delivered an Invited talk on “NIRF & Atal Ranking of Institution and Achievements (ARIIA)”, as pa... more Delivered an Invited talk on “NIRF & Atal Ranking of Institution and Achievements (ARIIA)”, as part of the webinar organized by Arasu Engineering College, Affliated to Anna University, Accredited by NBA Accredited by NAAC and Recognized by UGC under 20) and 12(B), Chennai Main Road, Kumbakonam 612 501, Tamil Nadu on 19-02-2021.

I have highlighted the need for NIRF Ranking, the steps to be taken, Importance of Indexed Publications

inproceedings by Narayan Krishnaswamy (Dr. Narayan K)

In this work, the design and optimization of compact taper is presented to enable coupling of inf... more In this work, the design and optimization of compact taper is presented to enable coupling of infrared light in the C-band with the nano-photonic silicon-on-insulator (SOI) integrated optical waveguide. The proposed compact taper results in ∼ 96% transmission efficiency for the taper length of ∼ 5 µm and ∼ 99.5% transmission efficiency for the taper length of 10 µm. The use of the proposed compact taper significantly reduces the foot print of optical coupler (grating and proposed compact taper) to (10 × 5) µm 2 with ∼ 96% transmittance and (10 × 10) µm 2 with ∼ 99.5% transmittance. The end-toend coupling loss is less than 0.01 dB in the C-band. The compact taper along with grating presented in this work can be used as an efficient optical coupler for mode coupling from fibre to SOI singlemode optical waveguide in high density optical integrated circuits operating at 1550 nm.

In this work we present a Comparative analysis between SOI waveguide and graphene based waveguide... more In this work we present a Comparative analysis between SOI waveguide and graphene based waveguide at visible wavelength, significant reduction in losses is observed in graphene based waveguide making it suitable for integrated optical biosensors.

In this work modeling of two dimensional fluorescence based bottom emitting Organic Light Emittin... more In this work modeling of two dimensional fluorescence based bottom emitting Organic Light Emitting Diode (OLED) using Moth eye Anti Reflective Coatings (ARC) is presented. The Finite Difference Time Domain (FDTD) mathematical modeling has been used to analyze the light extraction efficiency from fluorescence based Organic Light Emitting Diode (OLED). The OLED structure has been simulated by using 2D Moth-eye Anti Reflective coatings. The Finite Difference Time Domain (FDTD) method is used to model and simulate the OLED structure. An enhancement of Light Extraction Efficiency (LEE) has been achieved by inserting Moth-eye Anti Reflective coatings on the surface of the glass substrate which reduces reflection and increases the transmission. Comparative study is carried out between hexagonal photonic crystals and Moth eye Anti reflective coatings by placing these nanostructures on the substrate of OLED. The improvement in the far field intensity of OLED structure is achieved by optimizing the angular distribution of light through the substrate with moth eye anti reflective coatings.

Analysis of various SOI waveguide Bragg gratings subjected to MEMS actuation is reported in this ... more Analysis of various SOI waveguide Bragg gratings subjected to MEMS actuation is reported in this work. For communications and sensor applications, ridge waveguide based design is found to have better performance than rib based design.

Finite Difference Time Domain modelling of 2D-Photonic crystals is presented. The photonic band s... more Finite Difference Time Domain modelling of 2D-Photonic crystals is presented. The photonic band structure is analyzed to find the effects of Bloch vectors. The Organic Light Emitting Diode enhances Light extraction efficiency using photonic crystals.

In this work, a ring resonator is designed with two rings for the sensing application. The wavegu... more In this work, a ring resonator is designed with two rings for the sensing application. The waveguide is designed with 400nm wide and 180nm high. Both the rings are designed with 3.1µm radius each. The straight waveguide couples with the ring at 1550nm wavelength. The mode profiles and the spectrum of resonances are observed at mid-infrared wavelength, 1550nm. The measurements of the mode profile, refractive index and spectral properties of the design facilitate to monitor and modify the optical properties of the ring resonator structure. The phase shift in the resonance is observed, which can be implemented in the design of the sensor based ring resonator. In sensing applications the small size of ring resonator plays an important role, the interaction length of ring resonator with few tens of centimeters or even longer gives better sensing performance. Ring resonator offers enhanced light intensity near its surface with the enhancement being proportional to the Q-factor, which is due to the circulating nature of the resonant light. The coupling between the straight waveguide and the ring at 1550nm wavelength and is simulated using Lumerical FDTD. In optical sensors, a thin layer is attached to one of the ring surface, to observe the phase shift in the resonance. Since the refractive index of the thin layer on top of the ring structure is different from the surrounding medium which is typically water based, a change of index happens at the surface of the sensor which is measured for detecting the presence of additional layer in the cover medium. Hence the ring resonator structure can be implemented for bio-sensing application.

In this paper, a detailed simulation, modeling and analysis of photonic crystal cavity quantum do... more In this paper, a detailed simulation, modeling and analysis of photonic crystal cavity quantum dot laser is discussed. A photonic crystal structure is Nano device can be implemented as a biosensor. A waveguide coupled H1 cavity based photonic crystal is represented in which, these are separated structurally by orthogonal dipole mode coupling. Construction of cavity is achieved by piercing a slab Ta 2 O 2 (Refractive Index 2.0995) with air holes to form hexagonal lattice. The photonic crystal cavity quantum dot laser has two modes at 1430nm and 1491nm. Here a quantum dot is placed at a middle of the Nano photonic crystal cavity. Population inversion is achieved in a very short time because of the maximum field amplitude of 1e7V/m.

In this work, a ring resonator is designed to study the resonance characteristics. The resonance ... more In this work, a ring resonator is designed to study the resonance characteristics. The resonance characteristics of the ring resonator dependency on the ring diameter, waveguide width and the gap between the ring and waveguide are considered to be 6μm, 15μm and 0.1μm respectively. The resonance frequency, free spectral range (FSR), Quality (Q) factor of the resonances are determined. In this simulation, a liquid crystal (LC) is placed as a covering medium for biosensing application. Liquid crystal based Ring resonator is simulated at 1550nm wavelength.

Your article is protected by copyright and all rights are held exclusively by Springer Science+Bu... more Your article is protected by copyright and all rights are held exclusively by Springer Science+Business Media, LLC, part of Springer Nature. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to selfarchive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

† This paper is an extended version of our paper published in: Venkatesha, M.; Vismaya, K.R.; Pra... more † This paper is an extended version of our paper published in: Venkatesha, M.; Vismaya, K.R.; Prashanth, A.U.; Vyshnavi, M.; Narayan, K. Modeling and Analysis of SOI Grating Coupler for Bio-sensing Applications. Abstract: The design, modeling, and analysis of a silicon-on-insulator (SOI) grating coupler integrated with a microfluidic channel for lab-on-a-chip applications are presented. The grating coupler was designed to operate at 1310 nm. The simulated SOI structure consisted of a 220 nm top-Si device layer with an integrated waveguide, grating coupler, and a buried oxide layer of 2 µm. A rectangular microfluidic channel was deposited on the SOI optical grating structure for light and fluid interaction. The fluidic flow through the device was driven by centrifugal and Coriolis forces. The grating structure was designed to achieve a maximum coupling efficiency at the optimized injection angle of the light source. The sensitivity of the grating structure could be analyzed and evaluated using the change in coupled power as a function of the effective refractive index and was found to be 0.928 × 10 −6 RIU. The SOI optical grating structure along with the micro fluidic channel on top could be effectively used as an absorbance-based lab-on-a-chip biosensor.

In this work modeling of double layer motheye anti-reflective coating (DLAR) on organic light emi... more In this work modeling of double layer motheye anti-reflective coating (DLAR) on organic light emitting diode (OLED) is presented. Finite difference time domain method (FDTD) and Fresnel reflection theory is used to study the reflection and transmission of light of Organic Light Emitting Diode (OLED) using Anti-reflective coatings (ARC). The double layer motheye anti-reflective coatings are incorporated on the surface of glass substrate of an OLED. This is done to reduce the losses existing in OLEDs substrate-air interface. The refractive index (RI) of the top and bottom layer of ARC is engineered and the thickness of the top and bottom layer anti-reflective coatings is modelled using Fresnel's reflection theory. The effect of double layer motheye ARC on OLED for enhanced far field intensity is analysed. It is found that the far field electric intensity of DLAR based OLED has a significant enhancement compared to OLED with Single layer Antireflective coatings on the glass substrate.

In this work, a ring resonator is designed and analyzed for the spectral properties. A ring and a... more In this work, a ring resonator is designed and analyzed for the spectral properties. A ring and a bus waveguide is designed with a core width of 0.2µm and cladding width of 2µm respectively. The bus waveguide is designed with a height of 14.4µ, width of 2µm and a layer thickness of 900nm is considered. The structure is simulated with a wavelength of 1.55µm. The core refractive index of 2.5 and the cladding refractive index of 1.5 is considered in the design. The separation between the ring and bus waveguide considered in the design is 0.72µm. A perfect electric conductor is considered at the boundaries of the ring and the bus waveguide. The meshing of the structure is done, which involves the finite element method (FEM). The power at the input port is given as 1W. The coupling of the light in the core of the bus and ring waveguide is observed. Which will give a better limit of detection, and is required for biosensor. An increase in the transmittance is observed by reducing the radius of the ring, various ring circumference is considered for the analysis. A small ring structure is taken for consideration, as the smaller ring will be useful in the bio-sensing application, which can further be fabricated for a point of care devices.

The effects of anti-reflective coatings (ARC) on organic light emitting diode (OLED) optical char... more The effects of anti-reflective coatings (ARC) on organic light emitting diode (OLED) optical characteristics are reported in this paper. The light output produced from the OLED is not 100%. But the emitted light is trapped due to various Modes. The losses at the glass air substrate interfaces of an OLED are addressed in this work. The Anti-Reflective coatings increase the light output by reducing OLED reflections at the interface between glass and air. The Finite Difference Time Domain (FDTD) method and the Fresnel theory have been used to design the device and study the effects on OLED of the Single Layer Anti-Reflective Coating (SLAR) and Double Layer Anti-Reflective Coating (DLAR). The thicknesses and refractive indices of the layers of the anti-reflective coatings were optimized. We also compared the light out coupling power efficiency of the SLAR coated OLED with that of an OLED with a DLAR coating and also with Conventional OLED. The results show that the enhancement in light output efficiency of the DLAR coated OLED was slightly higher than that of the SLAR coated OLED.

Personal wearable medical devices and sensors have become more popular which results in better re... more Personal wearable medical devices and sensors have become more popular which results in better resources optimization and a better systematic monitoring or health condition. The ability to extract quantitative information in living cells without actual biopsy (disturbance in the structure of the cell) can be used to study and monitor morphological and physiological changes such as pre-cancerous or cancerous conditions. Basically, light scattered from a cell depends on the size of the cell, structure of the cell and the properties of the incident light. It is also termed as "optical biopsy". Such Mie scattering based Lab-on-a-Chip (LOC) sensor device if implemented can be used for early diagnosis of terminal diseases such as cancer. Gold nano particle acts as a sensor on this wearable device. Mie scattering based nonlinear optical phenomenon is used for cancer detection. This work involves modelling, simulation and analysis of a nano sensor using Discontinuous Gallerkin Time Domain method (DGTD). Light is used from arbitrary shaped objects at various incident angles. The Mie solution to Maxwell's equations describes the scattering of an electromagnetic plane wave by a homogeneous sphere. Mie scattering theory has been used to determine whether scattered light from tissue corresponds to healthy or cancerous cell nuclei using angle resolved low coherence interferometry. Gold nanoparticle has been used in biological applications and it is necessary to know the co-efficient of scattering and co-efficient of absorption. Mie scattering has no upper limits with respect to size of the particle.

Papers by Narayan Krishnaswamy (Dr. Narayan K)

Nanosphere structure are the suitable and efficient nanoparticle for the biological application i... more Nanosphere structure are the suitable and efficient nanoparticle for the biological application in designing the refractive index-based sensors. Modeling and analysis of Nanosphere structure is simulated. Nanosphere structure acts as a surface plasmon device. The Gold nanospheres are commonly used nano devices. The UV visible spectrum wavelength from 300nm-900nm is applied. The Mie scattering algorithm and dipole approximation methods are the modeling methods used. The cross-section efficiency and sensitivity of the nanosphere based refractive index sensor is analyzed. The mathematical analysis is conducted using discrete dipole approximation method. These are the part of the theory of scattering of light by nano particles which has homogenous and spherical in size. The Riccati-Bessel functions are used in the Mie calculations.

I have highlighted the need for NIRF Ranking, the steps to be taken, Importance of Indexed Publications

Wireless Personal Communications, Jun 20, 2022

Analysis of microcantilever beam and ARROW microcantilever waveguides are presented in this work.... more Analysis of microcantilever beam and ARROW microcantilever waveguides are presented in this work. The microcantilever is simulated by using the silicon nitride material. Electric voltage applied creates the deformation in the cantilever beam. The deformation leads to displacement of the beam. The displacement is due to bending of the cantilever tip. The integration of MEMS cantilever and ARROW waveguide results in the ARROW microcantilever waveguide. The ARROW microcantilever waveguide quality factor, electric filed intensity and sensitivity analysis are the three important parameters presented. The quality factor is obtained by varying the air gap distance between cantilever waveguide and output waveguide. Through this simulation using FDTD sensitivity up to 73.78 nm/RIU has been achieved for the microcantilever arrow waveguide.

Micromachines

This research focuses on enhancing the optical efficacy of organic photovoltaic cells, specifical... more This research focuses on enhancing the optical efficacy of organic photovoltaic cells, specifically their optical absorbance and electrical parameters. The absorbance of photons in organic solar cells (OSCs) was studied by incorporating an optical space layer and triple core-shell square-lattice nanostructures. For better chemical and thermal stability, a dielectric-metal-dielectric nanoparticle can be replaced for embedded metallic nanoparticles in the absorption layer. The 3D (finite-difference time-domain) FDTD method was used to analyze the absorption and field distribution in OSCs using 3D model morphology. Firstly, an optimization of thickness of the optical spacer layer was analyzed and secondly, the impact of adding triple core-shell nanostructures at different levels of an OSC were studied. The photovoltaic properties such as short circuit current density, power conversion efficiency, fill factor, Voc were investigated. The proposed design has demonstrated an improvement of...

2022 International Conference on Futuristic Technologies (INCOFT)

Materials Today: Proceedings, 2021

Lithium manganese oxide thin films have been deposited on nickel (Ni) and platinum (Pt) coated st... more Lithium manganese oxide thin films have been deposited on nickel (Ni) and platinum (Pt) coated stainless steel substrates at room temperature using powder target by Radio Frequency (rf) reactive magnetron sputtering. The samples are exposed to heat treatment at 500°C to form crystalline phase. Nickel and platinum thin film coatings have been carried out using direct current (DC) sputtering. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical characterizations have been carried out. XPS spectra indicate the presence of all elements present in the powder target. A discharge capacity of 54 mAh mm À1 cm À2 and 48 mAh mm À1 cm À2 has been obtained from charge discharge studies in the potential range 2.0 to 4.4 V for the thin film samples deposited on Ni and Pt coated SS substrates correspondingly Charge discharge cycles are conducted up to 40 cycles.

Lecture notes in electrical engineering, Sep 12, 2022

Microsystem Technologies, 2022

Design and analysis of high-sensitivity optical MEMS accelerometer based on waveguide Bragg grati... more Design and analysis of high-sensitivity optical MEMS accelerometer based on waveguide Bragg grating integrated with Crab-leg beam for low frequency applications is presented in this paper. Crab-leg beam are used to suspend the proof-mass to decrease spring stiffness with low device footprint. A waveguide Bragg grating is positioned on the shin of crab-leg to maximize strain sensitivity. To compensate for the temperature dependence of Bragg spectral properties, a reference grating positioned on the proof-mass is used. Due to excellent linear response, high-sensitivity of 184 pm/g and low fundamental frequency, the proposed accelerometer is suitable for microgravity and seismometry applications.

Clinical Biophotonics

Personal wearable medical devices and sensors have become more popular which results in better re... more Personal wearable medical devices and sensors have become more popular which results in better resources optimization and a better systematic monitoring or health condition. The ability to extract quantitative information in living cells without actual biopsy (disturbance in the structure of the cell) can be used to study and monitor morphological and physiological changes such as pre-cancerous or cancerous conditions. Basically, light scattered from a cell depends on the size of the cell, structure of the cell and the properties of the incident light. It is also termed as “optical biopsy”. Such Mie scattering based Lab-on-a-Chip (LOC) sensor device if implemented can be used for early diagnosis of terminal diseases such as cancer. Gold nano particle acts as a sensor on this wearable device. Mie scattering based nonlinear optical phenomenon is used for cancer detection. This work involves modelling, simulation and analysis of a nano sensor using Discontinuous Gallerkin Time Domain method (DGTD). Light is used from arbitrary shaped objects at various incident angles. The Mie solution to Maxwell’s equations describes the scattering of an electromagnetic plane wave by a homogeneous sphere. Mie scattering theory has been used to determine whether scattered light from tissue corresponds to healthy or cancerous cell nuclei using angle resolved low coherence interferometry. Gold nanoparticle has been used in biological applications and it is necessary to know the co-efficient of scattering and co-efficient of absorption. Mie scattering has no upper limits with respect to size of the particle.

Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology

Chemosphere

Although amitraz is one of the acaricides most commonly applied within beehives, to date, its tim... more Although amitraz is one of the acaricides most commonly applied within beehives, to date, its time-dependent oral toxicity in honeybees has not been investigated, due to amitraz's instability in aqueous media. In aqueous media such as honey, amitraz rapidly forms a continuously changing tertiary mixture with two of its major hydrolysis products, DMF and DMPF. The contribution of each hydrolysis product to the overall oral toxicity of this acaricide is not known. Therefore, we aimed to characterize the depletion and formation kinetics of amitraz and its hydrolysis products in 50% sucrose solution provided to caged honeybees, including the calculation of the 50% lethal oral concentration (LC50) of amitraz. We sought to determine the contribution of each component of the mixture to the overall observed toxicity. We also investigated the time- and concentration-dependent toxicity of the amitraz mixture and its hydrolysis products. A novel approach based on the analysis of the areas under the depletion and formation curves of amitraz and its hydrolysis products revealed that DMPF, amitraz and DMF accounted for 92%, 7% and 1% (respectively) of the overall toxicity of the mixture. The chronic oral LC50 of amitraz was 3300 μmol/L, of similar magnitude as that of the non-toxic hydrolysis product DMF. The toxicity of DMPF and the mixture decreased over time; whereas the toxicity of DMF increased over time. Amitraz's instability in aqueous media and the highly toxic profile of DMPF, suggest that DMPF is the actual toxic entity responsible for amitraz's toxicity toward honeybees.

Journal of Modern Optics

Let R = k[x1,. .. , xn] be a polynomial ring over a field k of characteristic zero and R be the f... more Let R = k[x1,. .. , xn] be a polynomial ring over a field k of characteristic zero and R be the formal power series ring k[[x1,. .. , xn]]. If M is a D-module over R, then R ⊗R M is naturally a D-module over R. Hartshorne and Polini asked whether the natural maps H i dR (M) → H i dR (R⊗R M) (induced by M → R ⊗R M) are isomorphisms whenever M is graded and holonomic. We give a positive answer to their question, as a corollary of the following stronger result. Let M be a finitely generated graded D-module: for each integer i such that dim k H i dR (M) < ∞, the natural map H i dR (M) → H i dR (R ⊗R M) (induced by M → R ⊗R M) is an isomorphism.

Proceedings of the 7th International Conference on Photonics, Optics and Laser Technology, 2019

Journal of Nanophotonics

Abstract. A simulation and analysis of a ring resonator-based sensor are presented. The ring reso... more Abstract. A simulation and analysis of a ring resonator-based sensor are presented. The ring resonator structure has two bus waveguides and two rings with a gap between the ring and the ring and bus waveguide. The radius of each ring is designed to be 3.1 μm. The ring resonator is designed such that both rings exhibit resonance at 1550 nm, and it is analyzed at mid-infrared wavelengths between 1500 and 1600 nm. The guided signal is launched through the bus waveguide to determine spectral properties, such as free spectral range and quality (Q-) factor. An improved Q-factor is observed in the simulation results for the optimized design. The improved Q-factor allows us to analyze the ring resonator for use in sensing applications.

Photonic Network Communications

A MEMS tunable integrated waveguide Bragg grating-based filter for C-band optical dense wavelengt... more A MEMS tunable integrated waveguide Bragg grating-based filter for C-band optical dense wavelength-division multiplexing (DWDM) network is presented and analyzed in this work. Waveguide Bragg grating being a notch filter in the transmission spectrum is used to realize a tunable filter by varying the applied voltages to the fixed–fixed beam loaded with this grating. The strain across the grating is enhanced by choosing MEMS beam configuration such that the metal electrode is the bottom-most layer of the composite fixed–fixed beam. Device dimensions are chosen to achieve a narrow full width half maximum of 0.77 nm, allowing filtering of adjacent channels of 100 GHz DWDM network. A large Bragg wavelength shift of 10.4 nm (1552.52–1562.92 nm) was achieved at 45.8 V actuation providing tuning for 14 DWDM channels with inter-channel cross talk below − 21 dB, with tuning range of 1.3 THz.

Journal of Micro/Nanolithography, MEMS, and MOEMS

Journal of Nanophotonics

Abstract. A moth-eye antireflective coating (M-ARC) on the surface of a glass substrate is report... more Abstract. A moth-eye antireflective coating (M-ARC) on the surface of a glass substrate is reported for enhanced efficiency of an organic light-emitting diode (OLED). The M-ARC reflects the light trapped in the substrate modes of the device. Fresnel’s theory was applied to study the reflection and absorption of light on the M-ARC. The effect of the M-ARC on the OLED for light out-coupling efficiency was analyzed using the finite-difference time-domain method. The improvement in light extraction efficiency of the OLED was optimized by investigating the parameters of pitch, thickness, refractive indices, and height of the M-ARC. The enhancement in peak extraction efficiency of the moth-eye-based OLED as a function of wavelength is ∼3.0 compared to conventional OLEDs.

2014 IEEE Healthcare Innovation Conference (HIC), 2014

ABSTRACT

International Journal of Biomedical and Clinical Engineering, 2013

Nano zinc ferrite powder was prepared by eco-friendly hydrothermal method. The prepared compound ... more Nano zinc ferrite powder was prepared by eco-friendly hydrothermal method. The prepared compound was well characterized by powder X-ray diffraction, scanning electron microscopy and UV-Vis spectophotometry. The compound formation was confirmed without any additional impurities. The PXRD data shows the crystallite size of the compound was about 6 nm. The SEM image showed the agglomeration of spherical nanoparticles. The UV-Vis spectrum and energy gap calculation confirmed the semiconducting behaviour of the sample. The magnetic properties of the compound revealed superparamagnetic nature at room temperature. These magnetic properties of the spherical nanoparticles are widely required in high performance devices like MRI contrast agent, cell separation and other biomedical applications.

In this work modelling of two dimensional of a fluorescence based Organic Light Emitting Diode (O... more In this work modelling of two dimensional of a fluorescence based Organic Light Emitting Diode (OLED) using plastic as flexible substrate is presented. The Finite Difference Time Domain (FDTD) mathematical modelling has been used to analyse the light extraction efficiency from fluorescence based Organic Light Emitting Diode (OLED). The OLED structure has been simulated by using 2D Hexagonal photonic crystal lattice. The Finite Difference Time Domain (FDTD) method is used to model and simulate the OLED structure. An enhancement of Internal Quantum Efficiency (IQE) and Light Extraction Efficiency (LEE) has been achieved by inserting Photonic Crystal above the emissive layer. The improvement in the extraction efficiency of OLED structure is achieved by increasing the radiative decay rate and by optimizing the angular distribution of light through the substrate.