4,385 research outputs found
Alligator in Winter Park, Fla.
No full textAn alligator seven feet, 3 inches in length. Photo taken by J.E. Barnes of Orlando, Fla. Photo selling for $12.00
Highly tunable and efficient diode pumped operation of Tm<sup>3+</sup> doped fibre lasers
No full textThe characteristics of a Tm3+ doped fibre laser pumped by a laser diode are reported. Operating at a wavelength of 1.94µm the laser had a threshold of 4.4mW, a launched power slope efficiency of 17% and 1mW output power. Measurements on the tuning rang of Tm3+ are presented and lasing is found to be possible from 1.65-2.0µm, the specific range depending on the fibre type. The largest range for a single laser was 300nm
Detailed characterization of Nd<sup>3+</sup> doped SiO<sub>2</sub> - GeO<sub>2</sub> glass fibre lasers
No full textSeveral basic parameters of Nd3+ in a SiO2 - GeO2 glass fibre have been determined. The stimulated emission cross-section for the 4F3/2 to 4I11/2 transition has been evaluated experimentally both by a laser technique and spectroscopically. Comparison is made between the two methods and a nonradiative decay process inferred. The efficiency of the 800nm pump band was determined from measurements of laser slope efficiencies. Branching ratios for the different fluorescent bands have been measured and cavity losses determined
The marriage record of Johnson, J. E. and Barnes, Eizabeth
No full textMarriage license for J.E. Johnson and Eizabeth Barnes. Walter M. McDonald was the officiant
Spectroscopic evaluation of the vibrational coupling of Er<sup>3+</sup> ions in phospho-aluminosilicate fibres and an explanation of compositional variations in Er-Yb 1.5 µm amplifier performance
No full textEvidence is presented that erbium will occupy one of two sites in phospho-aluminosilicate glass dependent on the Al : P ratio. Although high energy P=O vibrational modes are created we suggest these are localised and only couple to one type of Er site. Decay rates and Er-Yb amplifier performance are then critically determined by the Al : P ratio
High power ytterbium (Yb<sup>3+</sup>)-doped fibre laser operating in the 1.12µm region
No full textResults are presented for high power (>0.5W) Yb3+ fibre laser operating at a wavelength of around 1120nm pumped either by Nd:YAG (1.064µm) or Nd:YLF (1.047µm) lasers. The use of this laser as a single-wavelength pump for a Tm3+ ZBLAN upconversion fiber laser is also demonstrated
High-power sensitised erbium optical fibre amplifier
No full textMuch of the recent discussion regarding the systems deployment of erbium-doped fiber optical amplifiers has focussed on the pump source. Ideally, when choosing which pump band to use, one desires high efficiency, quantum limited noise performance, and the availability of a long-lived semiconductor based pump source. Initial experiments focussed on the 800 nm pump band of erbium due to its coincidence with commercially-available high-power AlGaAs diode lasers. Unfortunately, the presence of a strong excited state absorption (ESA) in this pump band severely limits the gain performance and degrades the amplifier noise figure. The pump wavelengths of 980 and 1480 nm have their advantages and disadvantages with regards to gain efficiency, amplifier noise figure and overall system advantages. However, there still remain questions with regard to pump laser reliability at both of these wavelengths. We describe here the operation of the sensitized erbium (Er3+/Yb3+) optical amplifier using a diode-pumped Nd3+ laser (DPL) as the pump source at 1064 nm. This approach indirectly utilizes highly non-diffraction limited high-power AlGaAs diode laser arrays and is easily power scalable, a notable advantage for a power optical amplifier. This pumping scheme operates without any noticeable ESA and exhibits a near quantum-limited noise figure. Previous work has focussed on the use of frequency-doubled DPL's at 532 nm as a pump source for erbium fiber amplifiers. In terms of overall efficiency, the utilization of the Nd3+ DPL fundamental as the pump source is a significant improvement and avoids the operational complexities of the nonlinear frequency-doubling process
Cooperative energy transfer in silica fibres doped with ytterbium and terbium
No full textResonant excitation Yb3+ at 974 nm (10267 /cm) in codoped Yb3+-Tb3+ silica based fibres has lead to luminescence clearly being visible from the Tb3+ 5D4 level (20661 /cm). Through time resolved fluorescence measurements we have been able to directly assign the process responsible for the fluorescence to cooperative sensitisation of the Tb3+ 5D4 level by two excited Yb3+ ions. Energy transfer times for the cooperative process have been directly measured, enabling the effects of glass structure on the cooperative process to be explored. Numerical simulations based on the experimental findings have been conducted, enabling both the mechanism for the luminescence to be confirmed and the properties associated with the luminescence to be interpreted
Yb<sup>3+</sup> sensitised Er<sup>3+</sup>-doped silica optical fibre with ultrahigh transfer efficiency and gain
No full textEfficient 1.54µm emission under 1064nm excitation of Er3+:Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, ~95% even under high inversion, is comparable to that in multicomponent glass fibres. The small signal gain of ~45dB is measured and power amplifiers with 145mW output power demonstrated
Yb<sup>3+</sup> sensitised Er<sup>3+</sup> doped, silica-based optical fibre with ultra-high transfer efficiency
No full textEfficient 1.54µm emission under 1064nn excitation of Er3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, of at least 85%, even under high inversion, is comparable to that in multicomponent glass fibres. Fibre design parameters are discussed and results presented. Small signal gain of ~45 dB is also measured and a power amplifier giving 145mW output power demonstrated.<br/
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