2,723 research outputs found
Estimation of a measure of disclosure risk for survey microdata under unequal probability sampling
No full textSkinner and Elliot (2002) proposed a simple measure of disclosure risk for survey microdata and showed how to estimate this measure under sampling with equal probabilities. In this paper we show how their results on point estimation and variance estimation may be extended to handle unequal probability sampling. Our approach assumes a Poisson sampling design. Comments are made about the possible impact of departures from this assumption
LeTourneau modified tank-tree crusher with R.G. LeTourneau and unidentified man.
No full textPhotograph of a Tree Crusher Tender built in Vicksburg, Mississippi and intended for use at the Tournata complex in Liberia, according to author Eric Orlemann. Shown with the tank are R.G. LeTourneau, left, and an unidentified man. The tank was never actually shipped to Tournata
Letter re: Shady Oak Farm party
No full textLetter from R.G. Mayer from the Consolidated Vultee Aircraft Corporation, thanking Amon Carter for the Shady Oak Party honoring American Airlines Officers and Directors
Photo of Air Force officials
No full textPhoto of Amon G. Carter with Brig. Gen. Roger M. Ramey and R.G. Mayer at the christening of the first "City of Fort Worth" B-36 airplane
Infrared thulium-doped fluorozirconate fibre lasers
No full textWe have investigated the performance of Tm3+-doped fluorozirconate fiber lasers when pumped at approximately 790 nm with a Ti:sapphire laser. This was done to assess which transitions are suitable for diode-pumping in addition to the 3F4 to 3H4 transition near 2.3 µm, as previously reported by Allen and Esterowitz
A high gain Tm<sup>3+</sup> fluorozirconate fibre amplifier operating in the 0.8µm region
No full textTo date, most research on rare earth doped optical fibre amplifiers has been directed towards developing high gain amplifiers in the second and third telecommunications windows at 1.3µm and 1.55µm respectively. In this paper we describe a Tm3+-doped fluorozirconate fibre amplifier pumped at 785nm and giving 20dB gain at 806nm in the first telecommunications window
Thulium doped fluorozirconate fibre lasers
No full textPumping of thulium-doped fluorozirconate fibre lasers at wavelengths available from semiconductor diodes around 790nm has enabled continuous wave laser operation at 806nm, 1.47µm, 1.97µm and 2.3µm, many of which may occur simultaneously. The performance of these laser transitions, including diode-pumped operation of the 3H4-3H6 transition at 1.97µm, is discussed
Theoretical and experimental investigation of a resonantly pumped thulium doped fluorozirconate fiber amplifier at around 810 nm
No full textWe have investigated the potential of thulium doped fluorozirconate fibers to provide an efficient AlGaAs diode pumped traveling wave amplifier at wavelengths around 810 nm. We present here calculations and experimental measurements of the small signal gain when excitation is resonant with the upper laser level. Amplification over the range 800-830 nm has been achieved in multimoded fiber with a best observed gain of 22 dB at 806 nm. Optimization of the fiber parameters is expected to provide an amplifier slope efficiency in excess of 0.7 dB/mW
CW diode-pumped operation of a 1.97µm thulium doped fluorozirconate fibre laser
No full textOperation of a diode-pumped continuous-wave thulium-doped fibre laser on the 3H4 - 3H6 transition at ~1.97µm is reported. The absorbed pump power at threshold for a multimode fibre with 40µm core diameter was measured to be ~20mW
Lasing and amplification in the 0.8µm region in thulium doped fluorozirconate fibres
No full textA thulium doped fluorozirconate fibre laser operating continuous-wave at wavelengths around 810 nm when pumped at 780 nm is reported. A slope efficiency of 15% with respect to incident pump power and a maximum output of 125 mW was achieved. This transition has the potential for laser diode pumping and with the output also being in the AlGaAs diode wavelength range there exist interesting possibilities for extending the versatility of such sources
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