Faculty Publications

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    Optimization of indium tin oxide-based all-optical switch using finite element method
    (American Institute of Physics, 2024) Sahu, S.K.; Khanna, A.; Vankalkunti, S.; Singh, M.
    The rapid development of optical communication systems necessitates the advancement of efficient and versatile all-optical switches. In this study, we propose an indium tin oxide (ITO)-based all-optical switch that harnesses the unique properties of this transparent conducting oxide material. The working principle of the proposed switch relies on the optical Kerr effect, where the refractive index of ITO changes by the influence of incident light. By exploiting the non-linear response of ITO to intense light pulses, we demonstrate its feasibility as a primary component in all-optical switching applications. With ITOs electric tunable ENZ effect, our proposed switch achieves an extinction ratio (ER) of 9.2 dB, insertion loss (IL) of 4.3 dB, and figure of merit (FoM) of 2.14. Our findings reveal that the ITO-based switch exhibits ultrafast response times and low energy consumption, making it suitable for high-speed optical networks. © 2024 Author(s).
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    Solar photocatalysis for treatment of Acid Yellow-17 (AY-17) dye contaminated water using Ag@TiO2 core-shell structured nanoparticles
    (2013) Khanna, A.; Shetty K, K.
    Wastewater released from textile industries causes water pollution, and it needs to be treated before discharge to the environment by cost effective technologies. Solar photocatalysis is a promising technology for the treatment of dye wastewater. The Ag@TiO2 nanoparticles comprising of Ag core and TiO2 shell (Ag@TiO2) have unique photocatalytic property of inhibition of electron-hole recombination and visible light absorption, which makes it a promising photocatalyst for use in solar photocatalysis and with higher photocatalytic rate. Therefore, in the present work, the Ag@TiO2 nanoparticles synthesized by one pot method with postcalcination step has been used for the degradation of Acid Yellow-17 (AY-17) dye under solar light irradiation. The Ag@TiO2 nanoparticles were characterized using thermogravimetric-differential thermal analysis, X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray analysis. The catalyst has been found to be very effective in solar photocatalysis of AY-17, as compared to other catalysts. The effects of pH, catalyst loading, initial dye concentration, and oxidants on photocatalysis were also studied. The optimized parameters for degradation of AY-17 using Ag@TiO2 were found to be pH 3, dye/catalyst ratio of 1:10 (g/g), and 2 g/L of (NH4)2S2O8 as oxidant. Efficient decolorization and mineralization of AY-17 was achieved. The kinetics of color, total organic carbon, and chemical oxygen demand removal followed the Langmuir-Hinshelwood model. Ag@TiO2 catalyst can be reused thrice without much decline in efficiency. The catalyst exhibited its potential as economic photocatalyst for treatment of dye wastewater. © 2013 Springer-Verlag Berlin Heidelberg.
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    Solar light induced photocatalytic degradation of Reactive Blue 220 (RB-220) dye with highly efficient Ag@TiO2 core-shell nanoparticles: A comparison with UV photocatalysis
    (2014) Khanna, A.; Shetty K, K.
    Ag core-TiO2 shell (Ag@TiO2) structured nanoparticles with Ag to TiO2 molar ratio of 1:1.7 were synthesized using one pot synthesis method and post calcination was carried out at 450°C for 3h to convert it from amorphous to crystalline form. The Ag core and TiO2 shell formation was confirmed by TEM and AFM. The particle size analysis revealed the average size of Ag@TiO2 as approximately around 30nm. EDS spectra showed the presence of O, Ag, and Ti elements. The improvement in optical properties was proved by DRS which showed significant red shift by Ag core in visible region. Ag@TiO2 exhibited better photocatalytic activity as compared to Degussa P25-TiO2, synthesized TiO2, and the Ag doped TiO2 photocatalysts under UV and solar light irradiation for degradation of Reactive Blue 220 (RB-220) dye. Higher rate of photocatalysis of RB-220 with Ag@TiO2 was obtained under solar light irradiation as compared to UV light irradiation, confirming the capability of the catalyst to absorb both UV and visible light. The kinetics of degradation of dye was found to follow modified Langmuir Hinshelwood (L-H) kinetic model. Ag@TiO2 can be recycled without much decline in the efficacy. Ag@TiO2 has been found to be the effective photocatalyst for degradation of water contaminated with azo dyes under both UV and solar light irradiations. © 2013 Elsevier Ltd.
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    Solar light-driven photocatalytic degradation of Anthraquinone dye-contaminated water by engineered Ag@TiO2 core–shell nanoparticles
    (Bellwether Publishing, Ltd., 2015) Khanna, A.; Shetty K, V.K.
    Abstract: The Ag core–TiO2 shell (Ag@TiO2) nanoparticles were synthesized by one-pot synthesis method followed by calcination and characterized using X-ray diffraction and transmission electron microscopy. The Ag@TiO2 core–shell-structured nanocatalyst was evaluated for its photocatalytic activity towards the degradation of Acid Blue-129 (AB-129), an Anthraquinone dye under solar light irradiations. The nanoparticles were engineered for efficient photocatalytic degradation of AB-129 by varying the parameters such as catalyst composition, calcination temperature, and calcination time. The catalyst composition with Ag to Ti molar ratio of 1:1.7, calcination temperature of 450°C, and time of 3 h were found to be the optimum for the efficient photocatalytic degradation of AB-129. The efficacy of Ag@TiO2 was compared with commercial TiO2, synthesized nano-TiO2, and Ag-doped TiO2 for the photocatalytic degradation of AB-129 and enhanced dye degradation was obtained with Ag@TiO2. This enhanced activity of Ag@TiO2 may be attributed to the trapping of conduction band electrons in Ag core and subsequent discharge on supply of air. Solar photocatalytic degradation of AB-129 dye using Ag@TiO2 followed Langmuir–Hinshelwood kinetics. Ag@TiO2 can be exploited as an efficient catalyst for the degradation of dye and textile industry wastewater. © 2014, © 2014 Balaban Desalination Publications. All rights reserved.
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    Aperture-Coupled Plasmonic Ring Resonator-Based Temperature Sensor: 3-D FEM Modeling
    (Institute of Electrical and Electronics Engineers Inc., 2024) Thayaba Nausheen, A.; Nakul Nayak, B.V.; Khanna, A.; Singh, M.
    Nanophotonic ring resonators have emerged as promising candidates for sensing applications due to their high sensitivity and compact footprint. In this study, we investigated a 3-D aperture-coupled plasmonic microring resonator (AC-PMRR)-cum-plasmonic spectral shaper as a temperature sensor using finite-element method (FEM). The sensor operates based on the principle of the temperature-dependent refractive index change of the surrounding medium, which modulates the resonance characteristics of the microring. The aperture coupling technique enhances the sensitivity and allows efficient excitation of localized surface plasmon resonances. We analyzed the sensing performance of the proposed device through rigorous numerical simulations. The effects of various design parameters, such as ring radius, aperture size, and coupling distance, on the sensor's performance are systematically examined. Furthermore, we explore the influence of material properties and temperature range on the sensor's sensitivity and resolution. The proposed refractive index sensor demonstrates a high sensitivity of ~0.065 nm/K, the figure of merit of ~102 RIU1, and detection accuracy of ~0.32 nm1, making it suitable for various temperature sensing applications in fields such as environmental monitoring, biomedical diagnostics, and industrial process control. © 2024 IEEE.
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    Temperature Detection Using Plasmonic Waveguide Ring Resonator: Design and Analysis
    (Institute of Electrical and Electronics Engineers Inc., 2024) Nausheen, T.A.; Nikhilesh Kumar, C.; Khanna, A.; Singh, M.
    A 3-D-hybrid plasmonic waveguide (HPWG) cascaded ring resonator-based temperature sensor is studied in the infrared (IR) spectral regime. The proposed design achieves high sensitivity and precision in temperature measurements by integrating the unique properties of plasmonic and photonics. The HPWG enhances the interaction between the optical field and the surrounding environment, while the cascaded ring resonators provide a compact and efficient means of modulating the optical signal in response to temperature changes. Our theoretical analysis and numerical simulations demonstrate that the device exhibits a significant shift in resonance wavelength with temperature variations, leading to an enhanced sensitivity (0.37 nm/K) compared to traditional photonic sensors. The potential applications of this temperature sensor span various fields, including environmental monitoring, biomedical diagnostics, and industrial process control. It offers a promising solution for advanced temperature sensing with improved performance and miniaturization. © 1973-2012 IEEE.