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We report a compact, highly sensitive all SMF refractive index (RI) sensor based on a waist enlarged tapered (WET) fiber probe with a micro-air cavity (MAC) located at the tip. The fabrication of WET probe has been accomplished using a commercial splicer machine and the MAC has been realized using ultrashort pulsed laser based micromachining. The WET fiber section facilitates excitation of cladding modes while the MAC in conjunction with the curved tip, provides a convenient platform for achieving core mode as well as cladding mode interference within the probe. The probe, with an optimized WET fiber section, exhibited maximum refractive index (RI) sensitivity of 123.7 nm/RIU with a negligible temperature sensitivity of 15.34 pm/°C. [ABSTRACT FROM AUTHOR]

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 $2\times 10^{-5}$ 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. [ABSTRACT FROM AUTHOR]

We propose a hybrid Tamm-plasmon-polariton (TPP) mode based sensing scheme for accurate determination of temperature. The sensing architecture is comprised of dual “metal-distributed-Bragg-reflector (DBR)” based structure, which sandwiches a common layer acting as a temperature sensing medium. Hybrid-TPP modes formed as a consequence of individual TPP mode-coupling is characterized by two distinct sharp reflectivity minima within the photonic bandgap of DBR for normal incidence of broadband source. The symmetric hybrid mode exhibits discernible variation in terms of change in reflectivity and resonance wavelength as the temperature of the sensing layer alters. On the other hand, the antisymmetric mode remains unchanged that gives rise to self-referenced temperature sensing scheme. We obtained a spectral sensitivity of 50 pm/°C by optimally choosing the thickness of sensing layer. In addition, the sharp TPP resonances gives rise to improved detection accuracy of such a sensing configuration as compared to competing optical sensing technologies. [ABSTRACT FROM PUBLISHER]

We present a comprehensive analysis for transverse electric (TE) and transverse magnetic (TM) polarized guided Tamm-plasmon polariton (TPP) mode at metal-heterostructure media interface. We explicitly show that the quarter-wavelength stack condition will not be satisfied for TE or TM polarized TPP mode due to the existence of null-point at metal-heterostructure media boundary. Therefore, we propose an alternate route to design TPP waveguide by solving the mode-dispersion relation for different geometrical parameters in a TiO2/SiO2 bilayer system. The guided TPP-modes (TE and TM) exhibit interesting dispersion characteristics which can be tailored as per the desired application. The group index of TM polarized TPP mode remains constant over a significant wavelength range which results into zero group-velocity dispersion (GVD) at λ ≈ 630 nm wavelength. Also, the propagation length for TM-polarized TPP modes vary between 25 μm to 50 μm in a 630-650 nm wavelength range. However, the variation of GVD for TE-modes exhibit a monotonic variation with an exceptionally large GVD ≈ -3 × 104 ps/km·nm around λ = 632.8 nm. [ABSTRACT FROM PUBLISHER]

We present a detailed study on waveguide design principle and propagation features of a channel Bragg-surface plasmon-coupled-waveguide (BSPCW). After proposing a convenient design route, we analyze the mechanism of coupling between bandgap-guided modes and surface plasmon polariton modes with respect to change in waveguide parameters such as type of metal, metal thickness and number of unit cells. In order to understand the physical mechanism behind the mode-coupling, we observe the redistribution of modal power of the BSPCW as wavelength changes. The interesting dispersion characteristics exhibited by the BSPCW supermodes opens a novel route to realize accurate sensors and efficient dispersion compensating modules in signal processing. Therefore, this comprehensive study could serve as a tool to optimize the performance of devices dictated by the application requirements in sensor technology and optical communications. The performance of the device in terms of sensing application is also being discussed. [ABSTRACT FROM PUBLISHER]

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 (\sim3 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. [ABSTRACT FROM PUBLISHER]