Faculty Publications
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Item High-Resolution Fiber Optic Sensor based on Coated Linearly Chirped Bragg Grating(Elsevier GmbH, 2020) Singh, M.; Raghuwanshi, S.K.; Prakash, O.; Kumar, P.K.a fiber optic strain sensor is proposed and experimentally demonstrated using fiber Bragg grating (FBG) based interrogation scheme. Due to fast response time and better sensitivity of graphene oxide (GO) material, coated linearly chirped fiber Bragg grating (LCFBG) is used in this work. Interrogation scheme is used for the efficient strain sensing by placing LCFBG within the Sagnac loop (wavelength dependent receiver). The GO deposition is confirmed by ultraviolet–visible spectroscopy, atomic force microscopy (AFM), and field emission scanning electron micrograph (FESEM). Our proposed fiber optic strain sensor possesses better resolution, stable operation in the infra-red region. In addition, sensor demonstrates 5.25 ?? static strain and 0.645 ??/?Hz dynamic strain resolutions, respectively. © 2020 Elsevier GmbHItem 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.