Saurabh Mani Tripathi

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In this paper we report a stable, label-free, bacteriophage-based detection of Escherichia coli (E. coli) using ultra sensitive long-period fiber gratings (LPFGs). Bacteriophage T4 was covalently immobilized on optical fiber surface and the E. coli binding was investigated using the highly accurate spectral interrogation mechanism. In contrast to the widely(More)
We propose a low-loss terahertz waveguide Bragg grating (TWBG) fabricated using a plasmonic two-wire waveguide and a micromachined paper grating for potential applications in terahertz (THz) communications. Two TWBGs were fabricated with different periods and lengths. Transmission spectra of these TWBGs show 16 dB loss and 14 dB loss in the middle of their(More)
We report fabrication of THz fiber Bragg gratings (TFBG) using CO(2) laser inscription on subwavelength step-index polymer fibers. A fiber Bragg grating with 48 periods features a ~4 GHz-wide stop band and ~15 dB transmission loss in the middle of a stop band. The potential of such gratings in the design of resonant sensors for the monitoring of paper(More)
We propose and demonstrate a temperature insensitive single-mode-multimode-single-mode fiber optic structure consisting of two in-series multimode fibers of appropriate lengths and of opposite temperature sensitivities. A simple approximate expression to estimate the required length ratio of the multimode fiber sections has also been derived whose(More)
We propose and demonstrate a novel temperature-insensitive bio-sensor for accurate and quantitative detection of Escherichia coli (E. coli) bacteria in water. Surface sensitivity is maximized by operating the long-period fiber grating (LPFG) closest to its turnaround wavelength, and the temperature insensitivity is achieved by selectively exciting a pair of(More)
We show theoretically that the fiber-optic devices using single-multi-single mode fiber structures can be made temperature insensitive by properly adjusting the concentration of P(2)O(5) in the core region of the multimode fiber used. Taking an example of a parabolic index multimode fiber, we obtain the temperature-insensitive transmission spectrum and(More)
In this Letter we report on fabricating and analyzing a temperature insensitive refractometer based on two concatenated dual-resonance long-period gratings (LPGs) with an appropriate inter-grating space (IGS) in between. The IGS provides a temperature-dependent extra phase difference between the core and cladding modes, making the refractometer similar to a(More)
A novel biochemical sensor based on a submicrometer size, high core-cladding index difference, silica core Si-SiO(2) waveguide with a Bragg grating written in its cladding region is proposed and analyzed. Waveguide parameters are optimized to obtain maximum sensitivity, and for lower refractive index samples, an optimum core width is found to exist for both(More)
We propose and demonstrate a wavelength tunable wavelength division multiplexing channel isolation filter based on two concatenated chirped long-period fiber gratings (LPGs). An intergrating space (IGS), deliberately introduced between the two gratings, provides an extra phase difference between the core and cladding modes. Changing this phase by heating(More)
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