1,720,966 research outputs found
Optical in-fibre grating high pressure sensor
No full textA high pressure fibre optic sensor using an in-fibre grating has been constructed. The wavelength of peak reflection from an in-fibre grating is tracked as it is pressurised, and a wavelength shift of 0.22nm at 70MPa hydraulic pressure has been observed. This sensor is expected to be an attractive choice for ultrahigh-pressure monitoring
Optical fibre sensor for high pressure measurement using an in-fibre grating
No full textA fibre optic sensor for monitoring high pressures, using an in-fibre grating, has been constructed. The method involves tracking the wavelength of peak reflection from an in-fibre grating as it is pressurised. Experimental trials, under the influence of hydraulic pressure, have been carried out and a wavelength shift of 0.22 nm at 70 MPa pressure was observed. The sensor should be an attractive choice for ultra-high pressure monitoring
Laser diode pumped waveguide lasers in neodymium-doped BK-7 glass
No full textIon-exchange in neodymium doped glasses has been used to fabricate waveguides which were optically pumped to realise lasers. The application of these layers as light sources in glass substrates will enhance the functionality of integrated optic systems in glass, allowing integration of active and passive devices. To obtain practical light sources, the neodymium-doped waveguides must be laser diode pumped to provide compact laser systems. Since the power available from a single stripe laser diode is limited, it is necessary to design the waveguide so that its modal field pattern matches that of the laser diode, thereby minimising the pump power required from the laser diode for the waveguide laser to reach threshold. We report on the fabrication and characterisation of waveguide laser pumped with a laser diode. These lasers operated in a continuous wave at a wave length of 1059nm, and were single transverse mode at both the pump and lasing wavelengths. The variation of the waveguide laser thresholds with the waveguide dimensions reveals the existence of an optimum dimension which minimises the laser threshold. A laser threshold of 20mW from the pump source and an overall slope efficiency of 5% with respect to the laser diode output power was obtained
Efficient blue light generation from a diode laser pumped Nd:YAG laser
No full textWe report on the efficient intracavity doubling of a 946 nm Nd:YAG laser with an LBO crystal at room temperature. A CW single-ended output power of 103 mW at 473 nm is obtained at a pump power of 2.58 W with an optical conversion efficiency of 4.0%. The overall efficiency is 7.2% if blue light output from both directions is taken into account. To our knowledge, this is the highest efficiency to date for a diode laser pumped compact Nd:YAG blue laser with a simple flat-concave resonator using a bulk nonlinear crystal for intracavity doubling
Fabrication, spectroscopy and laser performance of Nd<sup>3+</sup>-doped single-mode lead-silicate glass-fibres
No full textThe fabrication of a highly efficient Nd3+-doped single-mode fiber laser operating at 1.06km is described. The Nd3+ is introduced by doping Nd2O3 into a multicomponent (flint) lead-silicate glass host, Schott commercial optical glass FV. A fabrication technique for doping rare-earth evenly into commercial optical glasses is demonstrated. Spectroscopic properties relevant to laser operation in the Nd3+-doped lead-silicate glass fibers were measured and the influence of Pb2+ ions on the spectral properties was analyzed. Owing to the long lifetime and large absorption and emission cross-sections of Nd3+ in this lead-silicate glass host, a high-performance Nd3+-doped lead-silicate fibre laser device operating at 1.06µm has been successfully demonstrated
A comparative study of the laser performance of diode-laser pumped Nd:GdVO<sub>4</sub> and Nd:YVO4 crystals
No full textA comparative study of Nd:GdVO4 and Nd:YVO4 crystal lasers pumped by a cw diode laser has been conducted at the fundamental wavelengths of 1.06 µm and 1.34 µm, as well as when intracavity frequency-doubled to 532 nm and 670 nm, respectively. At these four wavelengths, maximum output powers from the Nd:GdVO4 crystal laser were 1.27 W, 800 mW, 610 mW, and 82 mW at a diode-launched pump power of 2.9 W. The threshold pump powers were 64 mW, 159 mW, 5 mW, and 12 mW, respectively. All the results obtained from Nd:GdVO4 were superior to those of Nd:YVO4, indicating that Nd:GdVO4 is a more efficient laser crystal than Nd:YVO4 for diode-pumped solid-state lasers. <br/
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
Experimental demonstration of intermodal dispersion in a two-core optical fiber
No full textThe recent prediction that intermodal dispersion can play a significant role in pulse evolution in a two-core optical fiber was confirmed experimentally. A picosecond pulse at 1.548µm launched into one core of a meters-long two-core fiber was found to come out of either core of the fiber as two temporally separate pulses. By measuring the time delay between these two pulses, the intermodal dispersion in the fiber was estimated to be 1.13ps/m, in good agreement with theory
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