Browsing by Author "Jha R."
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Item Accurate refractive-index sensing with tamm-plasmon and surface-plasmon based hybrid configurations(2014) Das R.; Srivastava T.; Jha R.We propose hybrid photonic modes formed due to coupling between Tamm-modes and surface-plasmon polariton modes for accurate measurement of refractive indices. We found sensitivity ?900 nm/RIU and detection accuracy ?30 ?m-1 for such sensing configuration. � OSA 2014.Item Accurate refractive-index sensing with Tamm-plasmon and surface-plasmon based hybrid configurations(2014) Das R.; Srivastava T.; Jha R.We propose hybrid photonic modes formed due to coupling between Tamm-modes and surface-plasmon polariton modes for accurate measurement of refractive indices. We found sensitivity ?900 nm/RIU and detection accuracy ?30 ?m-1 for such sensing configuration. � OSA 2014.Item All SMF inline Mach-Zehnder interferometer with micro cavity for curvature sensing(2015) Dass S.; Dash J.N.; Jha R.We propose cascaded taper based Mach-Zehnder interferometer with micro cavity as highly sensitive curvature sensor. Experimental results show that by changing the tapering parameters of second taper, curvature sensitivity of the system can be tailored. � OSA 2015.Item Avoided-crossings in dispersion properties of photonic-crystal-surface- plasmon-waveguides(2012) Das R.; Srivastava T.; Jha R.An analysis is presented for appreciating the mechanism of coupling of surface plasmon and bandgap guided modes. A design principle is proposed for designing such geometries and dispersion properties are studied by varying waveguide parameters. � 2012 OSA.Item AZO coated microchannel incorporated PCF-based SPR sensor: A numerical analysis(2018) Dash J.N.; Das R.; Jha R.An aluminum-doped zinc oxide (AZO) coated photonic crystal fiber (PCF) is proposed and numerically analyzed for surface plasmon resonance-based refractive index (RI) sensing. A microchannel is incorporated in this PCF, which is proposed to be fabricated using a pulsed laser. Such a structure is expected to have less roughness compared to that fabricated by mechanical polishing. Furthermore, properties such as no island formation and absence of intraband transition are added advantages of AZO. Numerical simulation shows that the maximum wavelength sensitivity and the corresponding resolution of this sensor are 5000 nm/RIU and 2 � 10-5 RIU, respectively. Furthermore, the amplitude sensitivity is found to be as high as 167 RIU-1. The proposed structure can be easily fabricated and utilized for sensing applications as it does not require either coating of metals on the inner surface of holes of PCF nor filling of the voids of PCF and it requires a small amount of analyte for RI monitoring. � 1989-2012 IEEE.Item Black Phosphorus: A New Platform for Gaseous Sensing Based on Surface Plasmon Resonance(2018) Srivastava T.; Jha R.We numerically demonstrate and propose sensitivity enhancement of surface plasmon resonance (SPR)-based conventional gaseous sensor using few layers of black phosphorous (BP), as compared with other 2D material such as graphene and molybdenum disulphide (MoS2). Results of our optimized numerical study show that with implementation of bilayer BP over a conventional gaseous sensor, sensitivity enhances by 35%, which is further increased up to 73% by addition of a monolayer MoS2 at an operating wavelength \lambda =633 nm. Therefore, the proposed SPR gaseous sensor could potentially open a new platform for high-performance gaseous sensing in the visible region. � 1989-2012 IEEE.Item Cascaded Taper Collapsed Region-Based PCF Sensor: Wavelength and Intensity Interrogation(2017) Dash J.N.; Jha R.We propose a highly sensitive and compact solid core photonic crystal fiber-based interferometric sensor with dual collapsed tapered region for the interrogation of curvature and temperature. The fabrication of the probe is accomplished by an economical commercial splicer. The distance between two tapered regions has been tuned so that the proposed probe can be used both in intensity and wavelength interrogation with a maximum curvature sensitivity of 18.8 dB m-1 and 14.76 nm m-1 in intensity and wavelength interrogation, respectively. Furthermore, the maximum temperature sensitivity is found to be 56 pm/�C thereby exhibiting negligible cross sensitivity. The response of the proposed probe to the applied curvature and environmental temperature is found to be linear. � 2001-2012 IEEE.Item Cascaded taper mach-zehnder interferometer based hydrophone(2014) Dass S.; Jha R.A cascaded taper Mach-Zehnder interferometer based hydrophone has been demonstrated for low frequency seismometric applications. Experimental results demonstrate that the proposed hydrophone exhibits an average sensitivity of 4.7 nm/kPa over frequency range of 15-100 Hz. � OSA 2016.Item Chalcogenide prism and graphene multilayer based surface plasmon resonance affinity biosensor for high performance(2012) Maharana P.K.; Jha R.Surface plasmon resonance based affinity biosensor comprising of 2S2G (Ge 20Ga 5Sb 10S 65) chalcogenide prism, graphene-multilayer and gold as a plasmon active metal is proposed for sensing over a broad wavelength range in visible and near infrared regime. We have investigated and carried out detailed analysis to design high performance affinity biosensor by exploiting the unique optical properties of chalcogenide glass and graphene. The performance of the biosensor has been quantified in terms of sensitivity and detection accuracy. The sensitivity of proposed biosensor increases significantly due to the presence of graphene where as the detection accuracy increases by more than 100% because of high index chalcogenide glass as compared to silica glass. Also, the detection accuracy of the proposed sensor in near IR is 16 times more as compared to that in visible. Adequate values of crucial design parameters have been optimized to achieve the best possible sensing performance over a broad wavelength range. � 2012 Elsevier B.V. All rights reserved.Item Channel Bragg-plasmon coupled waveguide(2011) Das R.; Jha R.; Srivastava T.We present a detailed analysis and recipe for designing a channel Bragg-plasmon coupled waveguide where the intermodal coupling between a band gap-guided mode and surface plasmon mode substantially modifies the phase velocity dispersion slope of supermodel. This leads to appreciably large group-velocity-dispersion with peak value of ? 4.33�104 ps/km-nm close to the optical communication band as well as interaction bandwidth of about 765 pm for 1 cm long waveguide. We also found that bandgap guided Bragg modes exhibit stronger dispersive features than the plasmon modes around ? 1.50 ?m which is exactly opposite to what is usually observed in visible region. The impact of waveguide parameters such as channel width etc. on mode-coupling mechanism is also studied with significant emphasis on the propagation loss suffered by the supermodes of the structure. � 2011 SPIE.Item Design considerations for plasmonic-excitation based optical detection of liquid and gas media in infrared(2011) Jha R.; Sharma A.K.Surface plasmon resonance (SPR) sensor schemes based on silicon (Si) and chalcogenide glass are evaluated and compared for chemical as well as gas detection in a wide range of infrared (IR) wavelengths. The plasmonic characteristics in IR are critically dependent on the dispersive behavior of the coupling substrate material. The performance of sensor has been evaluated in terms of its intrinsic sensitivity (IS) that includes the FWHM and angular shift of SPR curve for a given change in refractive index of sensing medium. Both these materials are potential candidates for opening up new routes for detection in near- and mid-IR due to their strong dispersion capabilities as compared to normal silica-based glass. The IS of chalcogenide glass-based SPR sensor is found to be larger than Si-based one for a broad wavelength range of 700-2500 nm indicating that chalcogenide glass-based probe provides more sensitive as well as accurate sensing procedure than Si-based probe. Further, for both glasses, the single probe can be used for both aqueous as well as gaseous sensing. Furthermore, for both glasses, it is found that the values of IS are much larger for gaseous sensing in comparison to liquid sensing. � 2010 Elsevier B.V.Item Diaphragm based single mode fiber taper acoustic sensor(2017) Dass S.; Jha R.[No abstract available]Item Dielectric over-layer assisted graphene, its oxide and MoS2-based fibre optic sensor with high field enhancement(2017) Nayak J.K.; Maharana P.K.; Jha R.A high-index fibre-core-based surface plasmon resonance (SPR) sensor using 2D materials such as graphene, graphene oxide (GO) and molybdenum disulphide (MoS2) on a silicon (Si) over-layer in visible and near infrared is reported. Si was used on silver (Ag) followed by different 2D materials of appropriate thickness on a 600 ?m core multimode fibre. Here Si is used to tune the resonance to a higher wavelength, and different 2D materials are used to enhance the performance as well as address the oxidation problem of Si. Moreover, a high-index chalcogenide core helps to decrease the full width at half maxima of the SPR spectra, hence increasing the detection accuracy of the sensor. Both the Ag and Si thickness are optimized, and the effects of different 2D materials on the performance of sensor are studied using the transfer matrix method in terms of electric field intensity, sensitivity, figure of merit (FOM) and resolution. We found that the percentage electric field enhancement for the Ag-Si-GO system is 4.65 � 104 in the presence of GO. The GO-based sensor is found to have a sensitivity of 202.2 nm RIU-1 in comparison to the graphene based sensor with a sensitivity of 189.4 nm RIU-1. Moreover, the FOM values are found to be as high as 5.57 RIU-1 for GO, and 5.18 RIU-1 and 2.29 RIU-1 for the MoS2 and graphene respectively. We believe that the proposed 2D-material-based sensors will open a new window for the development of high-performance fibre biosensors by utilizing the biocompatibility aspect of different 2D materials along with its high electric field value in the presence of a dielectric over-layer. � 2017 IOP Publishing Ltd.Item Dual tapered photonic crystal fiber based curvature and temperature sensor(2014) Dash J.N.; Jha R.We experimentally demonstrate a dual tapered solid core photonic crystal fiber (SCPCF) based modal interferometer for curvature and temperature measurement. The compact interferometer shows curvature and temperature sensitivity of 7.82 dB/m-1 and 42 pm/�C respectively. � OSA 2016.Item Effect of chalcogenide glass and plasmonic metal on electric field enhancement in surface plasmon resonance sensor(2012) Bharadwaj S.; Maharana P.K.; Das R.; Jha R.Plasmon active metals (gold and silver) along with chalcogenide glass have been used to enhance electric field intensity by 360% thereby significantly affecting the study of biomolecular interactions occurring in the vicinity of metal-analyte interface. � 2012 OSA.Item Electric field enhancement in surface plasmon resonance bimetallic configuration based on chalcogenide prism(2013) Kumar Maharana P.; Bharadwaj S.; Jha R.An aluminium-gold configuration for electric field enhancement based on surface plasmon resonance phenomenon is proposed. Our results and study show that for optimized bimetallic configuration (6 nm Au and 29 nm Al) along with chalcogenide prism, the electric field enhancement at the metal-analyte interface is more than 15 times greater and its probing depth is more than 300% longer than that of the gold based BK7 configuration thereby opening a new window for monitoring the biomolecular interactions in the vicinity of metal-analyte interface for various applications. � 2013 AIP Publishing LLC.Item Enhancing performance of SPR sensor through electric field intensity enhancement using graphene(2014) Maharana P.K.; Jha R.An ultra-stable high performance SPR sensor based on graphene on Ag configuration is proposed. The proposed sensor shows enhanced performance as compared to widely reported Au on Ag configuration. � 2013 IEEE.Item Experimental and theoretical studies on localized surface plasmon resonance based fiber optic sensor using graphene oxide coated silver nanoparticles(2016) Nayak J.K.; Parhi P.; Jha R.An optical fiber based refractive index sensor using graphene oxide (GO) encapsulated silver nanoparticles (AgNPs) is reported. The AgNPs are encapsulated with a very thin layer of GO as it controls the inter-particle distance thereby preventing aggregation. The encapsulation also enhances the colloidal stability and prevents the oxidation of the AgNPs by separating them from direct contact with the aqueous medium. High-resolution transmission electron microscopy results support the formation of 1 nm thick GO around AgNPs of an average size of 35 nm. A Raman spectrometer and a UV-VIS spectrometer have been used to characterize and study the synthesized nanoparticles along with GO. Further, Raman spectra support a 64.72% increase in D-peak intensity and a 52.91% increase in G-peak intensity of the GO-encapsulated AgNPs (GOE-AgNPs) with respect to GO. Further, the GOE-AgNPs are immobilized on the core of functionalized plastic-cladded silica fiber. FESEM confirms the immobilization of the GOE-AgNPs on the fiber core. We observed that the peak absorbance changes by 87.55% with a 0.05 change in the refractive index. The sensitivity of the proposed fiber sensor is found to be 0.9406 ?A/RIU along with a resolution of 12.8 � 10-4 RIU. MATLAB is used to calculate the absorbance of the AgNPs by considering the bound and free electron contribution along with the size-dependent dispersion of the nanoparticles. We found that the simulation results are in good agreement with the experimental results. � 2016 IOP Publishing Ltd.Item Fabrication and Theoretical Analysis of Square Knot Resonator for Sensing Applications(2018) Dass S.; Jha R.We demonstrate a new type of resonator called square knot resonator. The fabrication of this resonator is economical and it has a Q-factor of 12600. The demonstrated knot resonator can be potentially used for sensing strain, refractive index and curvature. � 2017 IEEE.Item Fabrication of fiber based inline micro air cavities with tunable geometrical parameters(2017) Dash J.N.; Jha R.We report a novel procedure to fabricate fiber based inline micro air cavities with tunable geometrical parameters over a wide range by tuning the length of hollow core photonic crystal fiber and splicing parameters. � OSA 2017.