Faculty Publications
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Item Complex Aware Transformer-CNN for Refractive Index Prediction in Plasmonic Waveguide(Institute of Electrical and Electronics Engineers Inc., 2025) Chaurasia, A.R.; Marwade, V.; Singh, M.Estimating the effective refractive index of a plasmonic waveguide with high precision is essential for various photonic applications. Traditional analytical and numerical methods often involve extensive computational methods. Deep learning-based approaches have shown promise in improving both accuracy and efficiency. This paper presents a deep learning-based approach for effective refractive index estimation using a hybrid Complex Aware Transformer-Convolutional Neural Network (CAT-CNN) model utilizing convolutional feature extraction, transformer-based attention mechanisms, and squeeze-and-excitation blocks to improve predictive accuracy. Trained on a dataset of plasmonic waveguide parameters at a fixed frequency of 193.2 THz, the model achieves a combined testing R2 score of 0.99978, demonstrating high precision in predicting the real and imaginary parts of the effective refractive index. Our results demonstrate that CAT-CNN achieves state-of-the-art performance in terms of prediction accuracy and computational efficiency. The proposed model has significant implications for the design of high-performance plasmonic sensors and integrated photonic devices. © 2025 IEEE.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 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 Nanoscale Tapered Hybrid Plasmonic Waveguide for On-Chip Silicon Photonics(Springer Science and Business Media B.V., 2022) Reddy, S.K.; Singh, M.Plasmonic waveguides which deploy surface plasmon-polariton (SPP) waves are of colossal interest to the researchers with their ability to realize and integrate nanophotonic circuits beyond the diffraction limit. In order to subjugate the demerits of plasmonic and dielectric waveguides, the light guided by plasmonic and dielectric waveguides are coupled to form hybrid plasmonic waveguide (HPWG). In this work, we have simulated a nanoscale tapered plasmonic waveguide (Au-SiO2-Si) using COMSOL Multiphysics software in the telecommunication C-band. The proposed waveguide shows better normalized effective mode area (Aeff/A= 0.056), enhanced electric field confinement, and long propagation length (Lp = 101.55 μm) with h= 350 nm, WAu = 100 nm, WSlot=20 nm, WSi = 220 nm, and ht=150 nm. The finite element method based approach shows that this enounced waveguide is a feasible choice for the future on-chip nanophotonic devices. © 2021, Springer Nature B.V.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 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 Plasmonic Biosensor for DNA Hybridization Using Integrated Graphene-Porous Silicon Waveguide(Institute of Electrical and Electronics Engineers Inc., 2023) Vankalkunti, S.; Singh, M.This work uses the full-vectorial finite element method to study a novel 3-D integrated graphene-porous silicon (p-Si) plasmonic waveguide-based nanostructure for deoxyribonucleic acid (DNA) hybridization. In this study, a p-Si waveguide is designed using the Maxwell Garnett model and is sandwiched between two low-indexed silicon dioxide (slot) layers. Next, a single graphene layer is deposited in both slot regions to enhance the sensor's absorption, tuneability, and sensitivity. The extraordinary optical transmission (EOT) through subwavelength nanoaperture reduces the ohmic losses and improves the optical transmission near the infrared region. Moreover, to optimize the sensor's design, a parametric analysis involving variations in the geometric dimensions of the sensor is performed using COMSOL multiphysics software. With 10% porosity of p-Si, the highest sensitivity value of 318.5 nm/RIU, 3.395/RIU figure of merit, 17.36 quality factor, and 0.01/nm detection accuracy with the presence of rectangular nanoaperture is achieved. Due to nanoscale size, the proposed label-free multilayer or hybrid plasmonic slot waveguide (HPSWG) biosensor offers the potential for future lab-on-a-chip (LOC) biological applications. © 2001-2012 IEEE.Item Hybrid Plasmonic Circular Aperture Waveguide for Blood Glucose Sensing(Institute of Electrical and Electronics Engineers Inc., 2024) Vankalkunti, S.; Singh, N.; Singh, M.A novel approach for blood glucose (or blood sugar) sensing utilizing a hybrid plasmonic circular aperture waveguide (HPCAW)-based nanostructure is proposed. The reported sensor combines the unique optical properties of plasmonic waveguides and circular aperture to achieve higher sensitivity and specificity in glucose detection. The HPCAW structure is designed to efficiently confine and propagate surface plasmon polaritons (SPPs) along the circular aperture, enabling enhanced light-matter interaction within the sensing region. Through rigorous numerical simulations and validation, we demonstrate the superior performance of the HPCAW sensor in terms of sensitivity (391.72 nm/RIU), figure of merit (FOM) (7.08 RIU-1), and detection accuracy (DA) (0.018 nm-1) compared to conventional glucose sensing techniques. Moreover, the proposed sensor offers inherent advantages, such as label-free detection, compact footprint, and compatibility with microfluidic systems. HPCAW provides a promising platform for the next-generation blood glucose monitoring applications with potential clinical translation. 1558-1748 © 2024 IEEE.