1,720,981 research outputs found
Power scaling of a 60% efficient, 793 nm pumped, 2 micrometres large mode area fibre laser
No full textA high-power diode-pumped thulium doped double-clad fibre laser has been developed to be used as a low-cost power scalable module. To date a power of 37 W, slope efficiency of 64%, and close to diffraction limited beam quality (M2~1.15) has been achieved.David G Lancaster, Alex Hemmings, Shayne Bennetts and Stuart D Jackso
Multiple-watt Tm3+, Ho3+-co-doped silica fibre laser tunable across both dopant transitions
No full textWe have obtained tunable laser emission across both Tm3+ and Ho3+ transitions in a 0.79-mum pumped Tm3+, Ho3+-co-doped silica fibre laser. For a 2.3 m fibre a 1920-2125 nm tuning range was measured with 3.6 W maximum power.Alexander Sabella, Alexander Hemming, Shayne Bennetts, Stuart D Jackson and David G Lancaste
A 226W hiqh power tm fibre laser
No full textWe have achieved 226W output power from a thulium doped fibre laser with 51% slope efficiency in a free-space architecture. The output beam quality was measured to be M2 = 2.0/2.4 at 110W output power.Alexander Hemming, Shayne Bennetts, Alan Davidson, Neil Carmody and David G. Lancaste
In-fibre resonant pumping of a fibre laser
No full textWe have developed and demonstrated a double-clad fibre laser which has an annulus doped with thulium that lases and resonantly pumps an inner core doped with holmium producing 86 mW at 2089 nm.David G Lancaster, Shayne Bennetts, Alex Sabella, Peter Henry and Stuart D Jackso
A high power hybrid mid-IR laser source
No full textAn efficient hybrid mid-IR laser system comprising a thulium fibre laser, Ho:YAG solid state laser and a zinc germanium phosphide optical parametric oscillator is presented. A 790 nm diode pumped 1908 nm thulium fibre laser operating at 30 W pumps an RTP q-switched Ho:YAG laser emitting 17 W at 40 kHz and 2090 nm. The zinc germanium phosphide optical parametric oscillator efficiently converts this into the 3–5 μm region producing 10.1 W with 59% optical conversion efficiency and an M2 = 1.5.Alexander Hemming, Jim Richards, Shayne Bennetts, Alan Davidson, Neil Carmody, Phil Davies, Len Corena and David Lancaste
Compact, all fibre, linearly polarised, single-mode Ytterbium doped fibre laser utilizing point-by-point inscribed intra-core fibre Bragg gratings
No full textWe report on the development of a compact, all fibre laser source operating at 1 μm with a linearly polarized (extinction ratio > 20 dB) and very narrow linewidth (12 pm) output. The unique cavity design included a fibre Bragg grating high reflector and output coupler, inscribed via the point-by-point method directly into the active core. A single splice within the cavity between the fibre incorporating the high reflector and the output coupler permitted re-orientation of the stressors at an angle of 90 degrees to each other, which produced a single lasing polarisation. This simple technique removed the need for a more complicated and expensive polarization controller.Nemanja Jovanovic, Graham D. Marshall, Alexander Fuerbach, Graham Town, Michael J. Withford, Shayne Bennetts and David G. Lancaste
A 4W tunable Tm3+:Ho3+ silica fibre laser
No full textA multiwatt Tm3+:Ho3+ co-doped silica fibre laser pumped at 0.79 μm is demonstrated with an extended tuning range from 1920-2120nm, compared with 1880-2040nm obtained using a Tm3+ only doped fibre. © 2008 Optical Society of America.Alexander Hemming, Alexander Sabella, Shayne Bennetts, Stuart D Jackson and David G Lancaste
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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