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Author: search.filters.author.Das R.Subject: search.filters.subject.Photonic bandgap

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    On the performance of Tamm-plasmon and surface-plasmon hybrid-mode refractive-index sensor in metallo-dielectric heterostructure configuration
    (2015) Das R.; Srivastava T.; Jha R.
    Hybrid modes formed as a consequence of coupling between Tamm-plasmon polariton (TPP) mode and surface plasmon polariton (SPP) mode in a metallo-dielectric heterostructure geometry exhibit interesting dispersive features which can be employed for realizing highly sensitive and accurate surface-plasmon-resonance (SPR) sensor. The transverse magnetically (TM) polarized TPP modes (TM-TPP), formed at the interface of distributed-Bragg reflector (DBR) and metal, are strongly dispersive as compared to SPP modes at optical frequencies that forms the basis of narrow interaction bandwidth which, in turn, results in improved accuracy of sensing. By deploying a nano/micro-fabrication compatible TiO2/SiO2-based DBR architecture in combination with different plasmon-active metals such as gold (Au), silver (Ag) and aluminum (Al), we propose a TM-TPP and SPP hybrid-mode sensor which exhibit high sensitivity ? 900 nm/RIU for analyte refractive indices varying between 1.330 and 1.345. The investigation also revealed that the hybrid-mode sensor is most accurate in case of Al-based configuration amongst Au, Ag and Al which is primarily due to weaker dispersion characteristics exhibited by Al at visible frequencies. Since, the dispersive behavior of TM-TPP modes could be tailored appropriately in any spectral band, the sensing configuration could be immensely useful for designing sensors at those wavelength where optical sources are readily available. � 2014 Elsevier B.V. All rights reserved.
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    High-performance bimetallic SPR sensor based on periodic-multilayer- waveguides
    (2011) Srivastava T.; Jha R.; Das R.
    We propose a high-performance bimetallic surface plasmon resonance (SPR) sensor based on periodic-multilayer waveguide and analyze its performance with respect to SPR active metals, such as gold (Au) and aluminum (Al). We found that an ultra thin (? 3 nm) layer of gold (Au) over aluminum (Al) protects aluminum (Al) from oxidation and exhibits better sensor performance. Using couple-mode theory, we show that the sensitivity and detection accuracy could be appropriately tailored for bimetallic (Au+Al) configuration. � 2011 IEEE.