1,720,978 research outputs found
Removing the directional degeneracy of LP11 mode in a fused-type mode selective coupler
Full text linkThe removal of polarization and modal degeneracy in the excitation of higher order modes is realised in all-fiber mode-selective weakly-fused-couplers by controlling the coupler geometry. Experiments carried out with short couplers show strong polarization dependency, while long couplers with a slow varying cross-section have shown to remove polarization and spatial degeneracy in the first high order mode
Simultaneous generation and enhancement of THG and SHG in a stable microfibre knot resonator
No full textThe simultaneous generation of third and second harmonics is demonstrated in microfiber knot resonators. This technique provides a stable configuration which improves efficiencies of the THG and SHG by 24 and 6 times respectively
Resonantly enhanced second and third harmonic generation in microfibre loop resonators
No full textDue to their strong modal confinement, optical microfibres (OMs) provide an excellent opportunity for studying nonlinear effects and in particular intermodally phase matched second (SHG) and third (THG) harmonic generation with predicted efficiencies up to 10-1 over several cm in an ideal uniform silica OM for both cases. Experimentally however, fabricating the required phase matching diameter uniformly over such lengths remains challenging. A simple solution is to reconfigure the OM as a resonator, such that pump recirculation near resonance increases conversion without the need for higher power sources or OM lengths greater than a few mm. Here, we theoretically study surface-SHG and THG in OM loop resonators by numerically solving the underlying coupled mode equations to determine the dependence of the enhancement on the resonance properties
Sensitive optical microfiber-based biosensors for DNA detection
No full textWe demonstrate an efficient method for DNA Sensing using simple devices, the microfiber coupler, and the Multi port Microcoil Resonator. These devices promise, high sensitivities, up to 200nm/RIU, and low detection limit of 10-6 RIU
Enhanced second harmonic generation in microfiber loop resonators
No full textSilica nanowires with high nonlinearities are attractive for a variety of applications such as continuum generation and new light sources. In particular, a growing interest was shown for using these nanowires for second harmonic generation (SHG) and third harmonic generation (THG) [1-3]. However, conversion efficiencies remain low, and new methods to improve this conversion are still required. In this work we experimentally demonstrate enhanced SHG using a nonlinear microfiber loop resonator, in which the recirculation of the resonant pump wavelengths enhances the second harmonic conversion and reduces the required pump power
Resonantly enhanced Faraday rotation in a microcoil current sensor
No full textA proof-of-principle experimental demonstration with theoretical modeling is presented for resonantly enhanced Faraday rotation in a microcoil current sensor. The recirculation of resonant light within the coil gives rise to an accumulated polarization rotation and thus improved responsivity. According to simulations, microcoil resonators with sharper resonances could offer significantly larger enhancements. This new type of current sensor has the potential to be ultrafast, compact, and low-cost
Selective excitation of high order modes in few mode fibres using optical microfibres
Full text linkSelective modal multiplexing and demultiplexing is demonstrated in few-mode fibers using weakly-fused microfiber couplers
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
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