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Dataset for thesis 'Femtosecond Laser Written Diffractive Optical Devices'
No full textData for University of Southampton Doctoral Thesis "Femtosecond Laser Written Diffractive Optical Device"</span
Data set for spectral and FT-ICR-MS analysis of dissolved organic matter in sediments of the New Britain Trench axis station
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<p>数据集包括原始数据和简单处理所需的数据、图表和文章。</p>
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<p>表格包含样品数量、收集深度、样品名称以及相应光谱和 FT-ICR-MS 数据的名称。</p>
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<p>例如,光谱数据包括荧光相对强度、荧光指数,而 FT-ICR-MS 光谱数据包括化合物类型相对强度以及化学式、元素比、等效双键数 (DBE) 和每个样品的芳香指数 (AImod)。</p>
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Femtosecond laser written diffractive optical devices
No full textThis thesis presents the development of optical diffractive and scattering-based devices fabricated by femtosecond laser direct writing. Structures investigated include waveguides, Fresnel lenses, diffractive gratings and scattering chips. Firstly, the laser induced refractive index change was estimated as 7×10−4 to 6×10−3 for writing powers of Pw=35 mW to 55 mW in silica. It was determined by fabricating waveguides and analysing their mode field diameter. A new writing method for controlling laser induced stress distribution was developed for improving the uniformity of inscribed structures and reducing laser-induced damage. A 36% diffraction efficiency improvement for a 50/50 grating was achieved compared to the standard multiscan writing technique. A two-layer Fresnel lens with a focal efficiency of 55% was also demonstrated. The writing technique was applied to create an integrated waveguide structure within multi-core fibre, thus forming a directional bend sensor, for which a sensitivity of -1.4 nm/degree was achieved. For a diffractive Fresnel lens, the design and the propagation simulation were demonstrated. For the high aspect ratio structure, Bessel beam writing has been utilised for a faster fabrication. A new method for refractive index estimation has been tested with the blazed diffractive grating. The diffraction efficiency of the grating has been investigated in both silica and lead silicate, a 57% diffraction efficiency was achieved with Gaussian beam writing. Finally, a laser-fabricated scattering chip based on induced voids was presented in this thesis, with applications as a wavemeter, spectrometer, and interferometric distance sensor. The algorithm based on the correlation and singular value decomposition has been demonstrated
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
Low bend loss femtosecond laser written waveguides exploiting integrated microcrack
No full textWe introduce the fabrication and use of microcracks embedded in glass as an optical element for manipulating light propagation, in particular for enhancing waveguide performance in silica integrated optics. By using a femtosecond laser to induce a strong asymmetric stress pattern in silica, uniform cracks with set dimensions can be created within the substrate and propagated along a fixed path. The smoothness of the resulting cleave interface and large index contrast can be exploited to enhance waveguide modal confinement. As a demonstration, we tackle the longstanding high bend-loss issue in femtosecond laser written silica waveguides by using this technique to cleave the outer edge of laser written waveguide bends, to suppress radiative bend loss. The microcrack cross section is estimated to be 15 μm in height and 30 nm in width, for the 10 [Formula: see text] 10 μm waveguides. At 1550 nm wavelength, losses down to 1 dB/cm at 10 mm bend radius were achieved, without introducing additional scattering. Both the cleave stress pattern and waveguide are fabricated with the same multiscan writing procedure, without requiring additional steps, and re-characterisation of the waveguides after 1 year confirm excellent long term performance stability.</p
Diffractive fresnel lens fabrication with femtosecond bessel beam writing in silica
No full textA 3-layer Fresnel lens with 52% diffraction efficiency was inscribed with a femtosecond Bessel beam in silica, with each layer being ∼80 μm An anomalous dispersion property was characterized with an RGB LED source.</p
Control of laser induced cumulative stress for efficient processing of fused silica
No full textLaser irradiation of silica glass is shown to trigger redistribution of material resulting in accumulation of stress and refractive index modification, and the rearrangement of the glass network has a significant impact on the quality of laser written optical components. We propose an alternative laser writing approach for achieving the desired refractive index and optical phase profiles through improved material stress control, demonstrated using both Gaussian and Bessel writing beams. The new material processing strategy is successfully adapted for implementing photonic circuits and diffractive elements with greater efficiency due to improved uniformity and symmetry of the induced index modification
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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