5,373 research outputs found
Polarisation effects in nonlinear microcoils
No full textOptical microcoil resonators (OMRs) fabricated by wrapping a microfibre around a rod to allow evanescent coupling between adjacent turns as in Fig 1. (a) have recently attracted much interest due to their high Q-factor and large extinction ratios resonances, low input and output coupling losses, large evanescent field and compactness [1,2], with applications such as sensing [3] and signal processing [4]. However, theoretical models published so far have neglected polarisation effects, and hence in order to develop a more detailed understanding we have modelled the OMR with polarisation-dependent coupled mode equations in the linear [5] and nonlinear regimes
Polarisation effects in optical microcoil resonators
No full textOptical microcoil resonators (OMRs) fabricated by wrapping a microfibre around a rod to allow evanescent coupling between adjacent turns as in Fig 1. (a) have recently attracted much interest due to their high Q-factor and large extinction ratios resonances, low input and output coupling losses, large evanescent field and compactness [1,2], with applications such as sensing [3] and signal processing [4]. However, theoretical models published so far have neglected polarisation effects, and hence in order to develop a more detailed understanding we have modelled the OMR with polarisation-dependent coupled mode equations in the linear [5] and nonlinear regimes
Marriage record of Hall, Maze and Lee, Mattie
No full textMarriage license for Maze Hall and Mattie Lee. G.R. Phillips was the officiant
Transmission properties of microcoils based on twisted birefringent fibre
No full textWe model the linear transmission properties of birefringent optical microcoil resonators (OMRs) by numerically solving polarisation dependent coupled mode equations. When the fibre is twisted, results show spectral bands where strong coupling between the different polarisations occur. The extinction ratio of certain resonances is also found to be enhanced by the exchange of power into another polarisation. Compared to the standard OMR, the choice of fibre twist and level of birefringence provide additional flexibility in tailoring the OMR spectral properties as needed for applications such as filtering, signal processing and sensing
Resonantly enhanced third harmonic generation in microfiber loop resonators
No full textWe theoretically study third harmonic generation in silica microfiber loop resonators wherein the large resonant field strength is exploited to increase the efficiency and reduce the required pump power, with a focus on the influence of loop parameters such as loss and coupling. For a 3 mm length loop, the conversion can reach several percent, that is, 640 times greater than an equivalent straight microfiber, for input powers as low as 100 W. The harmonic signal can be toggled between a high- and low-output state due to hysteresis at higher powers, and the efficiency can be further enhanced if the harmonic light is recirculated and coresonant with the pump
Nonlinear polarisation effects in optical microcoil resonators with fibre twist and birefringence
No full textWe study the nonlinear response of optical microcoil resonators (OMRs) based on twisted birefringent microfibres by incorporating Kerr nonlinearity into the underlying coupled mode equations. The resulting hysteresis characteristics were found to be highly polarisation dependent, with both the switching powers and contrast levels strongly influenced by the twist-induced cross-polarisation coupling. In addition, the existence of multiple bistability in OMRs is explored when the two orthogonal polarisations' resonances are spectrally close enough to influence the propagation of a monochromatic pump. Both the bistability and nonlinear switching may potentially be utilised for implementing polarisation-sensitive devices, especially for signal processing purposes, and benefit from the low threshold powers needed to observe nonlinear effects in OMRs
Erratum: Allen, G.R., Erdmann, M.V. & Purtiwi, P.D. (2017): Author Purtiwi, P.D. is spelled Pertiwi, P.D.
No full textAllen, G.R., Erdmann, M.V. & Purtiwi, P.D. (2017) Descriptions of four new species of damselfishes (Pomacentridae) in the Pomacentrus philippinus complex from the tropical western Pacific Ocean. Journal of the Ocean Science Foundation, 25, 47–76.
corrected spelling of third author’s name to:
Allen, G.R., Erdmann, M.V. & Pertiwi, P.D. (2017) Descriptions of four new species of damselfishes
(Pomacentridae) in the Pomacentrus philippinus complex from the tropical western Pacific Ocean. Journal of the Ocean Science Foundation, 25, 47–76
Berry phase magnification in optical microcoil resonators
No full textWe have studied the effects of the Berry phase on the linear transmission properties of optical microcoil resonators and analyzed the resonant behavior for different input polarizations and coil geometries. Contrary to previous expectations, we find that on resonance the size of the Berry phase shift can be magnified significantly, leading to a measurable polarization rotation for some geometries. Our model also considers other polarization effects including elasto-optic bend birefringence and the polarization dependent coupling coefficients, which were also previously neglected, and we still find that observable Berry phase effects persist. For example, in a three turn microcoil with a diameter of 0.2mm, close to 100% of an initially x polarized light will be coupled into the orthogonal y polarization, due to the optical activity arising from the cumulative effects of Berry phase on resonance. More generally, the cross-polarization coupling also significantly influences the resonance extinction ratio and quality factor
Intracellular trafficking and killing of Streptococcus pneumoniae by human alveolar macrophages are influenced by opsonins
No full textHuman alveolar macrophages (HAM) are the major resident phagocytic cells of the gas-exchanging areas of the lung. Following contact with macrophages, bacteria enter phagosomes, which gradually acquire the characteristics of terminal phagolysosomes, with incorporation of lysosome-associated membrane protein (LAMP). We measured the binding of type 1 Streptococcus pneumoniae to the surface of HAM and then measured subsequent internalization and phagosomal incorporation of LAMP-1 under various opsonic conditions. Opsonization with serum containing immunoglobulin resulted in significantly greater binding of pneumococci to HAM compared with opsonization with immunoglobulin G (IgG)-depleted serum containing complement, which in turn resulted in marginally increased binding over that observed in the absence of opsonization. Internalization of opsonized S. pneumoniae gradually increased to a maximum of 20% of bound bacteria by 120 min of warm incubation, with 20% of internalized pneumococci being localized within LAMP-containing compartments by 80 min. Internalization of opsonized S. pneumoniae by HAM correlated with a reduction of bacterial viability. When inocula were adjusted so that pneumococcal binding under different conditions was equalized, subsequent internalization, trafficking to LAMP-containing compartments, and reduction of bacterial viability were less efficient in the absence of opsonization than that observed following opsonization with adsorbed or IgG-replete adsorbed serum. Once bound to the surface of HAM, pneumococci opsonized with adsorbed serum with or without IgG were internalized, processed, and killed equally well. In conclusion, binding, intracellular trafficking, and killing of S. pneumoniae by HAM are each significantly increased by opsonization with serum containing immunogloblin and/or complement.</p
The philosophy poetry of G.R. Derzhavin: the contrast of life and death
No full textThis article is devoted to the eshatological philosophical concept of the G.R. Derzhavins’ poetry. The author describes the presentation of the theme of death and its artistic transformation in the works of the poet as the reception of the Orthodox tradition, a kind of the cultural memory
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