IDR @ IIT Bhubaneswar
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Item Highly sensitive D shaped PCF sensor based on SPR for near IR(2016) Dash J.N.; Jha R.A highly sensitive D shaped photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensor has been proposed. The use of Indium Tin Oxide as plasmonic metal helps in achieving SPR in near infrared region. The geometrical parameters of the proposed structure are similar to that of commercially available PCF which is widely available. Simulation results show that the proposed structure has a high wavelength sensitivity of 5200�nm/RIU with resolution of 1.92�נ10?5�RIU. � 2016, Springer Science+Business Media New York.Item Metal wire waveguide based all plasmonic refractive index sensor for terahertz frequencies(2016) Padhy P.; Sahu P.K.; Jha R.A terahertz refractive index sensor for liquid analytes consisting of a copper wire waveguide and co-axial layers of PMMA and PVDF is established numerically. The dispersion behavior of the fundamental core and surface mode and their phase matching has been demonstrated that clearly explains the working mechanism of the sensor. A core mode amplitude sensitivity of 59.9 for unit change in refractive index at 269.8 ?m is obtained for the proposed sensor. It has a large evanescent field penetration depth of 48 ?m at the phase matching point that can facilitate sensing of analyte refractive index further away from the interface. A definition for group velocity sensitivity is proposed which is then evaluated for the proposed sensor. The near dispersion free behavior of the sensor core mode except around the phase matching point gives it an excellent group velocity sensitivity of 128.9 for unit change in refractive index. � 2015 Published by Elsevier B.V.Item Ultrasensitive THz - Plasmonics gaseous sensor using doped graphene(2016) Purkayastha A.; Srivastava T.; Jha R.We propose a surface plasmon resonance (SPR) based gas sensor in terahertz frequency with Otto configuration based on attenuated total reflection (ATR) technique using free standing doped graphene monolayer. Angular interrogation method has been used to study the performance of the sensor in terms of sensitivity and detection accuracy. Different chemical potential of graphene monolayer has been investigated to study its effect on these performance parameters. The results show that the optimization of the gap distance between the prism base and the graphene monolayer has significant effect on the reflectivity of SPR sensing. This SPR based gas sensor shows ultrahigh sensitivity of 34.11 deg/RIU along with an ultrahigh Figure of Merit (FOM) of more than 1150 RIU-1. � 2015 Elsevier B.V. All rights reserved.Item Graphene based surface plasmon resonance gas sensor for terahertz(2016) Srivastava T.; Purkayastha A.; Jha R.We report a SPR based gas sensor using doped graphene monolayer employing the ATR technique via modified Otto coupling configuration. The proposed gas sensor is an approach different from the already reported Otto geometry for SP excitation in terahertz frequencies where the air gap has been replaced by a dielectric spacer layer (organic material) of refractive index (nd) 1.44, 1.50 and 1.54 at operating terahertz frequency of 5�THz. The performance of the sensor with respect to key system parameters such as the thickness of the dielectric layer, sensitivity, detection accuracy and FOM are investigated in the paper using angular interrogation via Transfer matrix method. It is observed that with increasing refractive index of spacer dielectric, the proposed gaseous sensor exhibits trade off between sensitivity and detection accuracy. However, the FOM is approximately equal for refractive indices 1.44 and 1.50 of spacer material, which is ~20�% higher than that at nd�=�1.54. The FOM for nd�=�1.44, increases from 527 (analyte refractive index�=�1.00) to 741 RIU?1 (analyte refractive index�=�1.10). � 2016, Springer Science+Business Media New York.Item On the electric field enhancement and performance of SPR gas sensor based on graphene for visible and near infrared(2015) Maharana P.K.; Jha R.; Padhy P.We propose a high performance surface plasmon resonance (SPR) affinity gas sensor based on graphene on Ag in visible and near infrared. Proposed sensor configuration has been optimized for maximum surface plasmon field at the sensing layer interface. The field intensity enhancement factor at sensing layer interface is found to be higher than that of silicon over layer on Ag thereby increasing the imaging sensitivity by 340%, 120% and 82% and detection accuracy by 440%, 150% and 100% as compared to Si on Ag configuration at ? = 653 nm, ? = 850 nm and ? = 1000 nm respectively. The performance of the sensor is found to be high over a broad refractive index range (1.0000-1.0008) of gaseous analyte with sensor resolution of 8 � 10-5 RIU and 2 � 10-5 RIU at ? = 653 nm and ? = 1000 nm respectively. We believe the proposed SPR based gas sensor configuration will open a new route for efficient gas sensing by riding on the advantage of graphene and latest nanofabrication techniques. � 2014 Elsevier B.V.Item On the Performance of Graphene-Based D-Shaped Photonic Crystal Fibre Biosensor Using Surface Plasmon Resonance(2015) Dash J.N.; Jha R.We propose a D-shaped photonic crystal fibre-based surface plasmon resonance sensor considering graphene on silver for sensing of refractive index of analyte and thickness of biolayer. The different structural and material parameters associated with sensor have been optimised. Graphene not only helps in adsorption of biomolecules due to ?-? stacking interaction but at the same time prevents oxidation of metal-like silver. Numerical simulation shows that amplitude sensitivity of the proposed structure for chemical analytes is 216�RIU?1 (refractive index unit) with a resolution of 4.6 � 10?5�RIU while the wavelength sensitivity of the proposed sensor is found to be as high as 3700�nm�RIU?1 with resolution of 2.7 � 10?5�RIU. Further, the proposed sensor can also be used for the detection of biolayer thickness in both amplitude and wavelength interrogations. An amplitude sensitivity of 0.26�nm?1 with resolution of 39�pm and wavelength sensitivity of 2�nm�nm?1 with resolution of 50�pm is achievable for the determination of biolayer thickness. The proposed structure is easy to use as there is no need of filling of voids, and the analytes can be placed easily on the flat surface of photonic crystal fibre (PCF). � 2015, Springer Science+Business Media New York.Item Sensitivity enhancement by air mediated graphene multilayer based surface plasmon resonance biosensor for near infrared(2014) Maharana P.K.; Jha R.; Palei S.Air mediated surface plasmon resonance sensor at near infrared frequency for sensitivity enhancement has been proposed. The proposed sensor utilizes the advantage of air gap between chalcogenide prism and gold film and high adsorption efficiency of graphene for enhancement of sensitivity. The thickness of air and gold film has been optimized for multiple wavelengths. Based on angular interrogation, the sensitivity of the proposed sensor can be tuned by changing the wavelength of operation in near IR and by judiciously selecting number of graphene layer. The sensitivity of the proposed sensor is 43.18 /RIU for 10 graphene layer at 700 nm where as at 1000 nm, the sensitivity is 36.14 /RIU for same number of graphene layer. We found that the sensitivity of the sensor increases linearly with sensing layer refractive index and number of graphene layer at a given wavelength. Also, we found that the detection accuracy of the proposed sensor in near IR increases by more than 290% for L = 10 as compared to conventional SPR sensor. We believe that the proposed sensor could potentially open a new possibility for high performance SPR sensing. � 2013 Elsevier B.V. All rights reserved.Item On the Performance of Highly Sensitive and Accurate Graphene-on-Aluminum and Silicon-Based SPR Biosensor for Visible and Near Infrared(2014) Maharana P.K.; Srivastava T.; Jha R.We demonstrate the numerical analysis of surface plasmon resonance biosensor based on graphene on aluminum and silicon. Employing matrix method, it is found that the proposed sensor exhibits high imaging sensitivity ?400 RIU?1 to 550 RIU?1 in a large dynamic range from visible to near IR region. It is observed that the application of monolayer or bilayer graphene over aluminum not only protects it from oxidation but also enhances the adsorption of biomolecules, which results in the detection of large refractive indices ranging from aqueous solution to biomolecules (refractive index 1.330 to 1.480) with overall high performance in terms of imaging sensitivity and detection accuracy. � 2014, Springer Science+Business Media New York.Item Highly Sensitive Plasmonic Temperature Sensor Based on Photonic Crystal Surface Plasmon Waveguide(2013) Srivastava T.; Das R.; Jha R.We propose a highly sensitive temperature sensor based on photonic crystal surface plasmon waveguides comprising different plasmonic active metals such as gold, silver, and aluminum, utilizing surface plasmon resonance phenomenon. We found that the resonance wavelength can be easily and substantially tuned over a broad spectral range by changing the temperature and also by judiciously choosing the different plasmonic metals. Employing coupled mode theory, we found that the proposed sensor can be used in harsh environment with sensitivity as high as ?70 pm/K around telecommunication window. � 2012 Springer Science+Business Media, LLC.Item On the field enhancement and performance of an ultra-stable SPR biosensor based on graphene(2013) Maharana P.K.; Padhy P.; Jha R.The effect of graphene on the electric field enhancement and performance of SPR-based sensor has been proposed and compared with Ag-Au bimetallic configuration. We found that a monolayer of graphene on Ag not only addresses the oxidation problem of Ag, but it also shows >30% field enhancement as compared with the widely reported Ag-Au bimetallic combination. Detailed calculations and simulations show that the proposed graphene-based sensor has >22% higher sensitivity and >38% narrower full-width at half-maximum than bimetallic. In addition, the better biomolecules adhesion due to graphene because of ?-stacking interaction may open a new window for ultra-stable high performance biosensors for real time bimolecular interactions. � 1989-2012 IEEE.