2,703 research outputs found
Frequency doubling, absorption and grating deformation in glass fibres: effective defects or defective effects?
No full textThe present understanding of colour centres in germanosilicate glass fibres and the diverse effects attributed to colour centre activity are reviewed. Drawing on a wide range of up-to-date research results, an attempt is made to piece together as far as possible a unified picture of the defect processes behind second harmonic generation, nonlinear transmission and photorefractive grating formation in optical fibres
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
Optically induced creation, transformation and organisation of defects and color centers in optical fibres
No full textOver the past five years, a colour-centre model for the dynamics of the absorption induced in germanosilicate fibres upon exposure to blue/green light has been under development at Southampton. This model is introduced and its predictions used for the first time to test our proposed Kramers-Kronig mechanism for the concurrent refractive index changes induced in the visible and the infra-red. It is found that the predicted colour-centre population changes in the UV are to explain these refractive index changes. A possible alternative model, based on density changes in the glass triggered by colour-centre formation, is assessed experimentally and analytically. The implications of this result to photonically driven self-organisation in fibres is briefly assessed, and reference made to recent experimental results
Picosecond laser micro-machining of glass for optics manufacture
Full text linkGlass-based aspheric optics are attractive for compact optical setups. In addition,
custom optics are useful for the correction of pointing errors of High Power Diode Lasers
(HPDL). The machining of fused silica (Corning HPFS® 7980), Schott N-BK7®, Schott
N-LaF21 and Ohara S-TiH53 using a Trumpf TruMicro 5X50 laser which provides a 6
picosecond pulse duration with a maximum pulse repetition rate of 400 kHz and
maximum average power of 50 W has been explored in this thesis. The machining of
these glass materials was carried out using laser wavelengths λ = 1030 nm, 515 nm and
343 nm at different pulse spatial overlap and fluence values. Two scan strategies were
used, namely the sequential raster scan strategy and the novel interlaced scan strategy. In
this thesis, we show the differences in the machining outcome. The sequential scan
strategy is similar to the standard raster scan technique and is limited to lower pulse
repetition rates of 20 kHz due to a thermal build-up effect manifesting itself in the
formation of fibres and fused debris on the surface. On the other hand, given the same
conditions of total pulse energy deposited on the surface, the interlaced scan strategy is
found to provide up to 3 times larger ablation depths. Furthermore, as the interlaced scan
strategy has been found to suppress the effects of thermal accumulation, higher repetition
rates up to 400 kHz could be used providing higher ablation rates up to 60 times more
than the sequential scan strategy on the laser used. A high-speed camera was used to
observe the mechanism of material removal for the two scan strategies providing insight
into the cause of the higher ablation efficiency of the interlaced scan strategy. We
demonstrate the capability of this process by machining cylindrical lenses. One batch of
the picosecond laser machined lenses was shipped to Fraunhofer ILT while another
similar batch of lenses was shipped to PowerPhotonic Ltd. for polishing using their CO2
laser polishing techniques. The polished lenses were tested for their performance, and
the accuracy of the process was measured. Finally, the future scope of this technology
along with its applications is discussed
Illustrated type catalogue of Amphidromus Albers, 1850 in the Natural History Museum, London, and descriptions of two new species
Full text linkCopyright Chirasak Sutcharit et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
Along the Waterfront. 80-year-old sailors Roger and Mary Duncan of East Booth
No full textAlong the Waterfront. 80-year-old sailors Roger and Mary Duncan of East Boothbay have a new schooner. Roger Duncan is the author of many nautical books
sj-pdf-2-jhs-10.1177_17531934211064185 - Supplemental material for The importance of embryology for parents of children with congenital hand differences
No full textSupplemental material, sj-pdf-2-jhs-10.1177_17531934211064185 for The importance of embryology for parents of children with congenital hand differences by Andrew D. Clelland, Órla Duncan and Wee L. Lam in Journal of Hand Surgery (European Volume)</p
sj-pdf-5-jhs-10.1177_17531934211064185 - Supplemental material for The importance of embryology for parents of children with congenital hand differences
No full textSupplemental material, sj-pdf-5-jhs-10.1177_17531934211064185 for The importance of embryology for parents of children with congenital hand differences by Andrew D. Clelland, Órla Duncan and Wee L. Lam in Journal of Hand Surgery (European Volume)</p
sj-pdf-3-jhs-10.1177_17531934211064185 - Supplemental material for The importance of embryology for parents of children with congenital hand differences
No full textSupplemental material, sj-pdf-3-jhs-10.1177_17531934211064185 for The importance of embryology for parents of children with congenital hand differences by Andrew D. Clelland, Órla Duncan and Wee L. Lam in Journal of Hand Surgery (European Volume)</p
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