227 research outputs found
Dataset for Removing the directional degeneracy of LP11 mode in a fused-type mode selective coupler
No full textDataset to support:
Ismaeel, R. and Brambilla, G. (2016) Removing the Directional Degeneracy of LP11 Mode in a Fused-Type Mode Selective Coupler. Journal of Lightwave Technology, 34, (4), 1242-1246</span
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
Removing the directional degeneracy of LP11 mode in a fused-type mode selective coupler
No full textThe 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
Prevalence and self-regulation of drivers’ secondary task engagement at intersections: An evaluation using naturalistic driving data
No full textOn the basis of naturalistic driving data, this study examined the prevalence of secondary task engagement at intersections and investigated how drivers self-regulate and manage such activities in accordance with changing roadways and demand situations. Video recordings were viewed to identify secondary tasks in which drivers engaged and situational factors, specifically those related to the complexity of driving situations. Results showed that one-third of the total intersection time was allocated to secondary task engagement and that greater engagement occurred at upstream and downstream areas of intersections than at areas falling within intersections. Drivers tended to more frequently engage in secondary tasks when their vehicles were stationary than when the vehicles were moving. Elderly drivers were less likely to engage in secondary tasks than younger drivers. Finally, drivers were less likely to engage in secondary tasks when they did not have priority than when they had priority and at intersections managed through traffic signs than in those controlled by traffic lights. In conclusion, drivers appear to engage selectively in secondary tasks at intersections in accordance with changes in the demands imposed by driving and roadway situations. In such circumstances, drivers likely respond to increased demand and reduce secondary task engagement to preserve processing resources. The findings offer the preliminary information necessary to develop driver training/education and awareness programmes on managing distractions and safe driving strategies
Selective excitation of high order modes in few mode fibres using optical microfibres
No full textSelective modal multiplexing and demultiplexing is demonstrated in few-mode fibers using weakly-fused microfiber couplers
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
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
Optical microfiber passive components
No full textOptical microfiber waveguides with diameters close to the wavelength of light possess an intriguing combination of properties, such a tight modal confinement, tailorable dispersion, and high nonlinearity, which have been utilized in many passive applications. Here, the key fabrication techniques and optical properties of microfibers are introduced, followed by a discussion of the various passive microfiber devices and sensors. Applications exploiting their strong confinement are reviewed, including harmonic generation, supercontinuum sources, gratings, tips for optical trapping and intracellular sensing and subwavelength light sources, as well as devices based on large evanescent fields such as couplers, interferometers, optical manipulators, sensors, and resonators. Furthermore, the properties and practical intricacies of manufacturing various microfiber resonators are evaluated, with a focus on their applications in sensing ranging from temperature monitoring to current, pressure, refractive index and chemicals detection
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