1,721,041 research outputs found
Multi-hole fiber based surface plasmon resonance sensor operated at near-infrared wavelengths
No full textWe propose a surface plasmon resonance (SPR) sensor based on a single mode optical fiber with six air holes. A thin gold film and a TiO2 film are deposited on the walls of air holes. Due to high refractive index of TiO2 the proposed sensor can operate at near-infrared (IR) wavelengths. The characteristics of the sensor were numerically investigated based on the finite-element method (FEM). The numerical results indicate that the optical loss spectrum of SPR sensor can be tuned easily by changing the thicknesses of gold and TiO2 layers. The refractive-index resolution of 2.7×10-5 (sensitivity S ~ 370/RIU) for aqueous analytes can be achieved
Long period grating inscribed in multimode fibre interferometer and its application in refractive index sensing
Full text linkA long period grating (LPG) is inscribed by a femtosecond laser in the multimode region of a singlemode-multimode-singlemode fibre device to provide a compact refractive index sensor. An average sensitivity of 39 nm/RIU and a resolvable index change of 2.56×10-4 are obtained experimentally with a 44.4 mm long multimode fibre over a measured refractive index range of 1.33-1.35. Because of its compactness, ease of fabrication, linear response, high sensitivity, easy connectivity to other fiberized optical components and low cost, this refractometer could find various applications in chemical and biological sensing
Compact all-fiber plasmonic Airy-like beam generator
No full textA compact all-fiber plasmonic Airy-like beam generator is demonstrated. A single slit and a 1D groove array were fabricated by focused ion beam milling on the gold deposited end facet of a single-mode optical fiber. The single slit excites the surface plasmonic polaritons (SPPs), which are decoupled into free space by the groove array. The phase of decoupling SPPs is adjusted by the grooves position. Experimental generation of the single Airy-like beam has good consistency with theoretical predictions. The transverse acceleration and nondiffraction properties are observed. The interference of double Airy-like beams in the free space is also analyzed. The presented plasmonic Airy-like beam generator is of importance to realize all-fiber optical trapping, beam shaping, and fiber integrated devices
Long period fiber grating and high sensitivity refractive index sensor based on hollow eccentric optical fiber
No full textWe have demonstrated experimentally a long period fiber grating (LPFG) written in a hollow eccentric optical fiber (HEOF). A high-quality LPFG with no structural deformation was fabricated using a highfrequency CO2 laser with a low energy density of 0.896 J/mm2. The LPFG writing parameters showed only a weak dependence on orientation of the fiber core to the writing beam. The liquid-filled HEOF LPFG has a high refractive index sensitivity of 1005 nm/RIU over a refractive index range of 1.422-1.441. The good performance and easy fabrication of the HEOF LPFG indicate that it is a promising platform for novel in-fiber microfluidic devices
Experimental observation and analysis of all-fiber plasmonic double Airy beams
No full textThe propagation dynamics of all-fiber plasmonic double parallel and orthogonal Airy beams are experimentally demonstrated. Two slits and groove arrays were fabricated by focused ion beam (FIB) milling on the gold coated end facet of an optical fiber to generate two Airy beams simultaneously. Sub-wavelength self-focusing of double parallel Airy beams in free space is experimentally verified. Effects of geometrical parameters on the intensity profiles of the focal spot are analyzed in detail. The characteristics at the junction of the two main lobes can be adjusted by controlling the initial phase difference of the two Airy beams. The propagation of two orthogonal Airy beams is also experimentally investigated. Multi-Airy beams are of importance to realize all-fiber optical trapping, fiber integrated devices, and laser shaping
In-line rainbow trapping based on plasmonic gratings in optical microfibers
No full textIn-line rainbow trapping is demonstrated in an optical microfiber with a plasmonic grating. The dispersions of x- and y-polarized surface plasmon polariton (SPP) modes are analyzed in detail by the 3D finite element method (FEM). In this system, the incident light is coupled from an optical microfiber into a graded grating. The plasmonic structure shows strong localization as the dispersion curve approaches cut-off frequency. Gradually increasing the depth or width of the grating elements ensures that the cut-off frequency of the SPP mode varies with the position along the microfiber. Near-infrared light at different frequencies can be trapped in different spatial positions. The in-line rainbow trapping is important for potential applications including optical storage, slow light, optical switch and enhanced light-matter interactions in fiber integrated devices and highly integrated optical circuits
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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