Faculty Publications
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Item Simulation study of multilayer hybrid plasmonic switch using Franz-Keldysh effect(SPIE spie@spie.org, 2020) Sahu, S.K.; Khoja, R.; Kanu, S.; Kumar, A.; Singh, M.ACMOS compatible three-port all-optical silicon switch working in 1.473 to 1.502 ?m (extinction ratio (ER) = 5.5 dB, ?C = 1.488 ?m) and 1.512 to 1.5306 ?m (ER = 3.079 dB, ?C = 1.52 ?m) bands is demonstrated in this work through numerical simulations. However, in spite of the all optical control, having null refractive index contrast between the transmitting and control waveguides of the switch causes the switching merit to deteriorate because of light leaking from the transmitting waveguide. Later, by employing Franz Keldysh effect-induced absorption coefficient tuning of Si1-x Gex (x = 0.85) to replace the silicon control port of the switch, 2.95-dB leakage reduction in the ON state is achieved, which is assessed in detail. Also, our numerical simulations confirmed the bandwidth of 38 GHz, which suggested a multilayer plasmonic waveguide structure. © 2020 Society of Photo-Optical Instrumentation Engineers (SPIE).Item High sensitivity detection of chemicals based on sinusoidally apodized structured grating assisted liquid filled directional coupler(Springer, 2021) Raghuwanshi, S.K.; Singh, Y.; Singh, M.; Chack, D.; Kumar, R.; Prakash, O.The grating has a significant role in sensing applications. Similarly, the grating-assisted coupler has excellent potential in chemical sensing applications. The power coupling between two closely coupled waveguide couplers can be significantly tuned by incorporating grating between them. The grating has been taken of silica material with sinusoidal shape in variation. The grating layer is assumed to be embedded within the sensing layer while considering a changeable effective refractive index depending on the sensing layer substances. In the present paper, grating assisted directional coupler has been numerically analysed using its own developed MATLAB-based algorithm of finite difference method (FDM) scheme. FDM method has been applied to solve the Eigenvalue equation to obtain allowed Eigenvalues and corresponding Eigen vectors (TE and TM cases). In FDM, the analysis domain has been fine discretized into the mesh of 1-D equal spacing for reasonable accurate computation results. In experimental validation, Fibre Bragg grating (FBG) has been suspended between two high refractive index coupler regions, which act as a power coupling zone. Also, the coupling length has been changed from 5 to 20 ? m for tuning purposes and then optimized for grating parameters viz. length, period, etc. The whole structure is 2-Dimensional (x and y directions) with invariant in the y-direction. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Porous-Silicon Assisted Hybrid Plasmonic Slot Waveguide Based On-Chip Ethanol Sensor(Institute of Electrical and Electronics Engineers Inc., 2022) Reddy, S.K.; Singh, M.Refractive index (RI) sensors have an overarching compass jutting into the biological and chemical fields and hence are efficacious. The evinced work appertains with an infra-red (IR)-band ethanol sensor, perceived with a Metal-Insulator-Semiconductor-Insulator-Metal (MISIM) waveguide structure consisting of porous-silicon as the absorbing/sensing medium. It is validated through modeling, and numerical simulations that the enhanced electric field confined into a low index slot undergoes a red-shift in wavelength in the presence of harmful ethanol. The red-shift in wavelength can be controlled by changing the silicon porosity and the physical dimensions of the hybrid waveguide. With finite-element-method based COMSOL Multiphysics simulations, we have obtained the optimized metrics of the sensor namely sensitivity (S TM) = 400.43-612.43 nm/RIU, figure of merit (FoM) = 12.42-19.46/RIU, and quality factor (Q-factor) = 46.8-52.9, for 10% to 25% p-Si porosity. The fabrication stages of the on-chip sensor are also articulated in brief. The detailed assessment shows that this sensor is a feasible choice for ethanol detection in hazardous environments. © 2001-2012 IEEE.Item High Sensitivity Refractive Index Sensor Based on Indium Antimonide Terahertz Plasmonic Ring Resonator(Institute of Electrical and Electronics Engineers Inc., 2022) Thomas, S.; Singh, M.; Satyanarayan, M.N.A high sensitivity refractive index semiconductor-insulator-semiconductor (SIS) waveguide with a ring resonator sensor at THz frequency is proposed. The topological study of the proposed filter is numerically simulated using the finite element method. A maximum sensitivity of 0.509 THz/ Refractive index unit (RIU) is obtained by filling the air-filled ring resonator cavity with different refractive index materials. Besides that, the transmission characteristics are studied by varying the structural dimensions and observed that the system can be treated as a frequency selective device. The device gets modified by incorporating another concentric ring inside the single ring. From the transmission characteristics, the multiple modes of the concentric dual ring are studied, and concluded that the even TM1 mode shows a better response towards frequency tuning. © 2001-2012 IEEE.Item Hybrid Plasmonic Waveguide Based Platform for Refractive Index and Temperature Sensing(Institute of Electrical and Electronics Engineers Inc., 2022) Sahu, S.K.; Reddy, S.K.; Singh, M.; Avrutin, E.A nanoscale 3D hybrid plasmonic waveguide (HPWG) refractive index-cum-temperature sensor has been proposed and simulated in this work. The aqueous analyte (benzene C6H6) sensing is possible over the wavelength range from 1.18∼μ m to 2.2∼μ m. A well-known refractive index (RI) sensing method (or wavelength interrogation) is considered for the proposed Si-TiO2-SiO2-Au nanostructure. The sensor design includes, titanium dioxide (TiO2) layer deposited over the silicon dioxide to enhance the overall sensitivity of the HPWG sensor. The finite element method (FEM) based 3D-numerical simulations are performed for an IR band signal, predicting 1022.75 nm/RIU device sensitivity and 2.95 nm/°C temperature sensitivity. The proposed sensor is suitable for next-generation on-chip biochemical sensing applications with nanoscale dimensions, low cost, and high sensitivity. © 1989-2012 IEEE.Item High-Performance All-Optical Hybrid Plasmonic Switch Using Zn-Doped Cadmium Oxide(Institute of Electrical and Electronics Engineers Inc., 2023) Sahu, S.K.; Singh, M.In this article, a novel hybrid plasmonic waveguide (HPWG)-based all-optical switch (AOS) using zinc-doped cadmium oxide (ZnCdO) is reported and numerically investigated with the finite-element method. This oxide layer, which is a well-known transparent conductive oxide (TCO), can be switched from a dielectric to a metallic phase by electrical tuning the refractive index. The mobility of free-carrier concentration is highly magnified with a nonlinear optical effect induced by the epsilon-near-zero material near the telecommunication wavelength. We have simulated the plasmonic switch using the COMSOL Multiphysics simulator, predicting 13.75 dB extinction ratio (ER), 0.5 dB insertion loss (IL), and 27.5 figure-of-merit (FoM) at 1.55 \mu \text{m} wavelength. We also performed the reliability study by varying parameters, such as the width and height of the waveguide, which affect the performance of the on-chip switch design. In addition, the proposed AOS can be easily integrated with future silicon photonic circuits for ultrafast switching applications. © 1973-2012 IEEE.Item Sensitivity improvement of photonic crystal refractive index sensor using porous silicon nano rods(Elsevier Ltd, 2023) Mehta, S.; Vankalkunti, S.; Kachhap, P.K.; Gautam, P.R.; Singh, M.This work proposes a photonic crystal refractive-index sensor for detecting volatile organic compounds (VOC). Two sensor designs are analyzed with Y-splitter photonic crystal waveguide using the finite-difference time-domain (FDTD) method. Also, simultaneous monitoring of two different analytes is possible across the arms of the Y-splitter. The porous silicon (p-Si) rods with a porosity of 25% are used to create a variable refractive index sensing region, which induces a relative shift in the resonant wavelength of the traveling mode. The response at the output ports is monitored in terms of transmittance power versus wavelength plot. The numerical simulations confirm ∼195.83 nm/RIU sensitivity and ∼24.482 RIU−1 figure-of-merit in the presence of hazardous alcohols. © 2023 Elsevier LtdItem Plasmonic Elliptical Nanohole Array for On-Chip Human Blood Group Detection(Institute of Electrical and Electronics Engineers Inc., 2023) Sahu, S.K.; Singh, M.A novel refractive index (RI) plasmonic biosensor with high sensitivity for human blood group detection is proposed and numerically investigated in the visible and near-infrared (NIR) regime. The proposed structure is based on a metal-insulator-metal (MIM) waveguide with an array of elliptical nanoholes. These nanoholes are used as the sensing surface and support important optical properties, such as extraordinary optical transmission (EOT) and nanoscale confinement of light. We have simulated and optimized the biosensor using RF module of COMSOL Multiphysics software, predicting the sensitivity values of three blood groups (A, O, and B) as 64.26, 101.16, and 82.1 nm/RIU, respectively. High sensitivity, precision, and portability make the reported sensor highly valuable for point-of-care applications, emergency situations, and resource-limited settings. By reducing the time for blood typing procedures and small sample volume requirements, MIM biosensor has the potential to enhance patient care and streamline medical processes. © 2023 IEEE.Item 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.Item Engineering Porous Silicon-Based Plasmonic Microdisk Resonator for Highly Sensitive Methanol Sensing(Institute of Electrical and Electronics Engineers Inc., 2024) Mehta, S.; Nakul Nayak, V.B.; Singh, M.This study introduces a novel application of a plasmonic microdisk resonator as a highly sensitive sensor for detecting methanol vapor. Leveraging the inherent advantages of plasmonic nanostructures, the microdisk resonator demonstrates a remarkable capability to detect minute concentrations of methanol. In this work, we modeled a novel 3-D porous-silicon (p-Si)-based hybrid plasmonic aperture-coupled microdisk resonator (HPACMR) with specific dimensions and porosity to optimize the sensitivity toward methanol vapor detection. The resonator's design incorporates a thin layer of copper on a dielectric microdisk, creating a plasmonic cavity that supports localized surface plasmon resonances. Finite element method-based simulations predict strong interactions between the resonator's plasmonic field and methanol molecules, leading to detectable shifts in the resonant frequency. By tuning the layout dimensions and p-Si properties, we achieved an altitudinous sensitivity of 569.52 nm/RIU and a Q-factor of nearly 370. The sensors' miniature footprint and potential for integration into portable devices make it an attractive candidate for field-deployable applications. © 2001-2012 IEEE.