Faculty Publications
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Publications by NITK Faculty
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Item The theoretical model for realization of an all-fiber, polarization independent Group Velocity Dispersion (GVD) compensating module with transfer function given by Chebyshev polynomials of the second kind is proposed and investigated. The proposed realization of the GVD compensating module comprises of Mach-Zender interferometers formed by single mode fiber optic directional couplers. The realization of GVD compensating modules using single mode fiber optic couplers as proposed in this paper is superior to an earlier realization of a similar GVD compensating module, which used bulk optic components such as TiO2 birefringent crystals, polarizers and ?/4 plates. © by Fachverlag Schiele & Schön 2005.(An all-fiber polarization independent GVD compensating module) Kumar, M.S.; Bhat, K.N.H.; Umesh, G.2005Item Self-compression of attosecond high-order harmonic pulses(2007) Kim, K.T.; Kang, K.S.; Park, M.N.; Imran, T.; Umesh, G.; Nam, C.H.Self-compression of attosecond high-order harmonic pulses in the harmonic generation medium itself has been demonstrated. The attosecond pulses were generated in an argon-filled gas cell and compressed by exploiting the dispersion characteristics of argon. Since the harmonic generation medium itself was used as the compression medium, continuous chirp control was easily achieved by adjusting the gas pressure. The optimized attosecond pulse was also the most intense, and its duration of 206 as was very close to the transform-limited value of 200 as. © 2007 The American Physical Society.Item XPM-induced crosstalk with higher order dispersion in SCM–WDM optical transmission link(Elsevier GmbH journals@elsevier.com, 2012) Kumar, N.; Sharma, A.K.; Kapoor, V.In this paper, the XPM-induced crosstalk has been evaluated with higher order dispersion in SCM–WDM optical transmission link at different modulation frequencies. It has been observed that there is exponent increase in XPM-induced crosstalk with the increase in modulation frequency from 0 to 3 GHz. The impact of 3OD, 4OD and 5OD is small as compared to 2OD but still contributes when the combined terms are considered. The combined effect of second, third, fourth and fifth-order dispersion parameters is that the induced crosstalk introduced by XPM increases. © 2011 Elsevier GmbHItem Highly birefringent photonic crystal fiber with hybrid cladding(Academic Press Inc. apjcs@harcourt.com, 2019) Krishnan, K.; Malavika, R.A highly birefringent hybrid cladding photonic crystal fiber (PCF) is proposed in this article. The guiding properties of the proposed PCF are numerically investigated using the finite element method (FEM). This fiber exhibits very high birefringence in the order of10-2 at communication wavelengths. In addition, low confinement loss of 6.1 × 10?3 dB/km, lower negative dispersion of -274.5ps/nm/km and higher nonlinearity of 76.41W-1km-1 is achieved at the same wavelengths compared with the exist literature. The proposed simple cladding structure is easy for fabrication. Moreover, effective mode area and nonlinear coefficient are analyzed and optimized. The proposed fiber can prove its applications in sensing, telecommunication and non-linear technologies. © 2018 Elsevier Inc.Item Dispersion-Engineered Transmission Line Loaded Slot Antenna for UWB Applications(Institute of Electrical and Electronics Engineers Inc., 2019) Paul, P.M.; Kandasamy, K.; Sharawi, M.S.; Majumder, B.A transmission line (TL) loaded, compact, ultrawideband (UWB) square slot antenna is proposed in this letter. The square slot is a microstrip line fed and loaded with an array of periodically perturbed TLs to achieve a UWB response from 2.1 to 11.5 GHz. The slot is designed to resonate at 2.6 GHz. The TLs are dispersion engineered to resonate at several frequencies so as to provide a wideband response. Loading of the engineered TLs on the square slot produced multiple resonances without affecting the fundamental mode of the slot antenna. The proposed antenna design is analyzed using dispersion relations and equivalent circuits. The proposed antenna is fabricated on an RT/Duroid 5880 substrate with a size of 50 × 50 × 1.52 mm3. The antenna performance metrics, such as impedance bandwidth, gain, and efficiency, are experimentally verified. Good agreement is obtained between simulated and measured results. © 2018 IEEE.Item Wave Interaction With Floating Elastic Plate Based on the Timoshenko-Mindlin Plate Theory(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2019) Praveen, K.M.; Karmakar, D.; Guedes Soares, C.In the present study, the wave interaction with the very large floating structures (VLFSs) is analyzed considering the small amplitude wave theory. The VLFS is modeled as a 2D floating elastic plate with infinite width based on Timoshenko-Mindlin plate theory. The eigenfunction expansion method along with mode-coupling relation is used to analyze the hydroelastic behavior of VLFSs in finite water depth. The contour plots for the plate covered dispersion relation are presented to illustrate the complexity in the roots of the dispersion relation. The wave scattering behavior in the form of reflection and transmission coefficients are studied in detail. The hydroelastic performance of the elastic plate interacting with the ocean wave is analyzed for deflection, strain, bending moment, and shear force along the elastic plate. Further, the study is extended for shallow water approximation, and the results are compared for both Timoshenko-Mindlin plate theory and Kirchhoff's plate theory. The significance and importance of rotary inertia and shear deformation in analyzing the hydroelastic characteristics of VLFSs are presented. The study will be helpful for scientists and engineers in the design and analysis of the VLFSs. © 2019 by ASME.Item Investigating the solubility of petroleum asphaltene in ionic liquids and their interaction using COSMO-RS(Korean Society of Industrial Engineering Chemistry A-803 Twin Bldg 275-3 Yangjae-Dong Seocho-Kul Seoul 137-130, 2019) Rashid, Z.; Wilfred, C.D.; Iyyaswami, I.; Arunagiri, A.; Murugesan, M.Dispersion of asphaltene in crude oil using ionic liquids (ILs) is being considered as a viable solution, in extraction and transportation processes. In this work, the interplay between asphaltene and ILs has been studied systematically to understand the effect of structural variation of ILs on asphaltene solubility. The activity coefficient of the total of 1517 ILs with different combinations of cation and anion of ILs for representative asphaltene molecule (asphaltene) was estimated via COSMO-RS (Conductor-like Screening Model for Real Solvents). COSMO_RS predictions were validated using experimental data on asphaltene solubility. Among the studied ILs, asphaltene showed high solubility in imidazolium-based ILs with hydrophobic anions. The present approach paved a way forward to rationally understand the impact of structural variation of ILs on their interaction with asphaltene molecule and to design new ILs for the dispersion and stabilization of asphaltene. © 2019 The Korean Society of Industrial and Engineering ChemistryItem High-Intensity Ultrasound-Assisted Low-Temperature Formulation of Lanthanum Zirconium Oxide Nanodispersion for Thin-Film Transistors(American Chemical Society service@acs.org, 2020) Pujar, P.; Madaravalli Jagadeeshkumar, K.K.; Naqi, M.; Gandla, S.; Cho, H.W.; Jung, S.H.; Cho, H.K.; Kalathi, J.T.; Kim, S.The process complexity, limited stability, and distinct synthesis and dispersion steps restrict the usage of multicomponent metal oxide nanodispersions in solution-processed electronics. Herein, sonochemistry is employed for the in situ synthesis and formulation of a colloidal nanodispersion of high-permittivity (?) multicomponent lanthanum zirconium oxide (LZO: La2Zr2O7). The continuous propagation of intense ultrasound waves in the aqueous medium allows the generation of oxidant species which, on reaction, form nanofragments of crystalline LZO at ?80 °C. Simultaneously, the presence of acidic byproducts in the vicinity promotes the formulation of a stable as-prepared LZO dispersion. The LZO thin film exhibits a ? of 16, and thin-film transistors (TFTs) based on LZO/indium gallium zinc oxide operate at low input voltages (?4 V), with the maximum mobility (?) and on/off ratio (Ion/Ioff) of 5.45 ± 0.06 cm2 V-1 s-1 and ?105, respectively. TFTs based on the compound dielectric LZO/Al2O3 present a marginal reduction in leakage current, along with enhancement in ? (6.16 ± 0.04 cm2 V-1 s-1) and Ion/Ioff (?105). Additionally, a 3 × 3 array of the proposed TFTs exhibits appreciable performance, with a ? of 3-6 cm2 V-1 s-1, a threshold voltage of -0.5 to 0.8 V, a subthreshold swing of 0.3-0.6 V dec-1, and an Ion/Ioff of 1-2.5 (×106). © © 2020 American Chemical Society.Item Dual Frequency Multi-Functional via-Less Leaky Wave Antenna Featuring Enhanced Frequency Sensitivity and Dual Beam Scanning Capability(Institute of Electrical and Electronics Engineers Inc., 2024) Majumder, B.; Vinnakota, S.S.; Goud Rangula, M.; Kandasamy, K.In this paper we present a dual band low cross-polarized periodic microstrip leaky wave antenna (LWA) based on the multi mode resonator concept (MMR). The structure is capable of frequency dependent backward dual-beam steering and fast forward beam scanning in the upper and lower operating band, respectively. A gap loaded microstrip line is used as a host transmission line to feed the combination of the periodic patch radiators on the top and the bottom etched slots leading to the generation of the forward and the backward space harmonics. The etched ring slots at the bottom surface of the structure are not only responsible for steering the beam in the backward direction in the bottom hemisphere in its upper band but also adds radiation diversity in the overall radiation mechanism in its two operating bands. The potential use of this antenna resides in its ability to produce in-plane fast forward beam steering suitable for autonomous vehicle navigation systems in its lower band and out-of-plane backward-symmetric dual beam steering in the upper operating bands, suitable for tracking in relay systems. © 2013 IEEE.