1,720,968 research outputs found
Micro fluorescence profiling of erbium doped fiber preforms
No full textA micro-fluorescence technique for profiling the spatial distribution of erbium ions doped into optical fibre preforms is reported. Profiles have been compared using fluorescence at wavelengths of 0.553 and 1.5 µm to identify a critical erbium concentration of about 0.12 wt% Er3+, where the effects of clustering become apparent. The addition of core co-dopants has been studied and found to have no significant effect on the active ion distribution. The variation in 1.5 µm fluorescence lifetime with position across the core has been measured. A pronounced reduction (up to 66%) in this lifetime at the core extremities was observed and indicates the presence of local ion environment disordering.<br/
Frequency shifted feedback and frequency comb generation in an Er<sup>3+</sup>-doped laser
No full textThe temporal and spectral characteristics are reported of an Er3+ -doped fibre laser incorporating frequency shifted feedback. The output of the free running laser was found to be either continuous-wave or train of driven relaxation oscillations depending on cavity loss. The performance is described and a simple theoretical model is used to predict the main features. Under cavity matching conditions, a train of pulses was generated with a repetition rate equal to the roundtrip time. Injection seeding of the laser generated a discrete comb of optical frequencies for applications in optical metrology
Efficient high-power continuous-wave operation of monomode Tm-doped fibre laser at 2µm pumped by Nd:YAG laser at 1.064µm
No full textDescribes the efficient 2 µm operation of a monomode Tm3+-doped silica-based fibre laser pumped with a Nd:YAG laser at 1.06 µm. The maximum fibre laser output power was 51 mW at 2.038 µm for an absorbed pump power of 230 mW. The threshold power was 60 mW absorbed and the slope efficiency with respect to absorbed power was 30%
A 1-Watt thulium-doped CW fibre laser operating at 2µm
No full textWe report efficient high power (>1W) single transverse mode continuous-wave laser action at 2 µm in a thulium-doped silica-based fibre laser pumped by a Nd:YAG laser at 1.064 µm. The highest measured output power was 1.35 W. A threshold of 600 mW absorbed and slope efficiency of 37% with respect to absorbed power were observed
Efficient operation of a Yb-sensitised Er fibre laser pumped in the 0.8 µm region
No full textThe dependence of threshold and slope efficiency on pump wavelength around 0.8µm has been investigated for an Yb-sensitised fibre laser. Results confirm a wider choice of pump wavelength compared with unsensitised Er fibre. A 5mW threshold and slope efficiency of 8.5% were observed for 820-830nm pumping
Efficient superfluorescent emission at 974nm and 1040nm from a Yb-doped fibre
No full textEnd-pumping of an Yb-doped single-mode fiber has yielded > 10 mW and 30 mW of broadband superfluorescence at 974 nm and 1040 nm respectively. Slope efficiencies > 40% have been obtained. Pump wavelength dependent linewidths between 2 nm and 19 nm have been observed
An Ytterbium-doped monomode fibre laser: broadly tunable operation from 1·010µm to 1·162µm and three-level operation at 974nm
No full textContinuous-wave laser action has been observed from an ytterbium doped monomode fibre laser on the three-level transition at 974 nm and on the four-level transition at 1036nm with slope efficiencies of 67% and 77% respectively, with respect to absorbed power. Tuning behaviour is described, in which polarisation control by means of fibre loops has allowed smooth continuous tuning from 1.010 µm to 1.162 µm
Frequency upconversion in Tm- and Yb:Tm-doped silica fibers
No full textFrequency upconversion has been observed and studied in Tm3+-doped and Yb3+-sensitized Tm3+-doped silica fibers. In the singly singly doped fiber upconversion to the blue and UV has been observed under excitation in the red (660 nm) and infra-red (1.064µm). In the co-doped fiber upconversion has also been observed under excitation at around 800-900 nm
Continuous-wave oscillation of a monomode ytterbium doped fibre laser
No full textThe last few years have seen intense interest and activity in the field of rare earth doped monomode fibre lasers and amplifiers [1,2],since these components could be used in fields as diverse as medicine and communications. Furthermore their small active volume offers a number of important advantages over conventional bulk glass lasers. We have chosen to investigate ytterbium doped fibre as it provides a very "clean" system (ie free from excited state absorption. Apart from the energy levels around 11,000cm-1 there are no other levels until the ultra-violet). The ytterbium fibre laser should therefore offer a good system on which to test some of the basic physics of fibre lasers. In addition it offers 3-level, 4-level and quasi 3-level laser transitions. Published work on ytterbium doped glass lasers in bulk form has been sparse with the main publication being that of Snitzer [3]. In this paper we describe the characteristics of an ytterbium-doped, silica based, monomode fibre laser operating at discrete wavelengths in the range 1035nm to 1076nm
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