P R Tapster
Defence Evaluation and Research Agency
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Publication
Featured researches published by P R Tapster.
Applied Optics | 1987
John G. Rarity; Kevin D. Ridley; P R Tapster
We show that a parametric downconversion crystal emitting angle resolved coincident photon pairs can be used to measure the absolute quantum efficiency of a photon counting detection system. We have measured the quantum efficiency of a silicon avalanche photodiode, operated in Geiger mode, as a function of operating voltage and compare this to results obtained using a conventional method.
Applied Optics | 2000
John G. Rarity; Thomas E. Wall; Kevin D. Ridley; P C M Owens; P R Tapster
We evaluate the performance of various commercially available InGaAs/InP avalanche photodiodes for photon counting in the infrared at temperatures that can be reached by Peltier cooling. We find that dark count rates are high, and this can partially saturate devices before optimum performance is achieved. At low temperatures the dark count rate rises because of a strong contribution from correlated afterpulses. We discuss ways of suppressing these afterpulses for different photon-counting applications.
Optics Communications | 1987
John Rarity; P R Tapster; E Jakeman
Abstract We report the first observation of sub-poissonian photon statistics for light generated by the use of a detection triggered optical shutter in parametric downconversion. A normalised second factorial moment of the photon counting distribution of 0.42 has been achieved with a pre-detection Fano factor of 0.984.
IEEE Circuits & Devices | 1999
Anders Karlsson; Mohamed Bourennane; Gregoire Ribordy; Hugo Zbinden; J Brendel; John Rarity; P R Tapster
Quite a few groups have turned their attention to using commercially available InGaAs/InP APDs, originally developed for optical communication applications, as SPADs for photon counting at 1300 nm and 1550 nm. This research has turned out to be quite fruitful, and there are many applications emerging in optical metrology (optical time-domain reflectometry) in eye-safe range finding and in future quantum technologies, where databits are encoded on individual photons. This article describes the status of these commercially available InGaAs/InP APDs used as single-photon counters in the telecom wavelength region of 1550 nm.
Applied Optics | 2000
Michael R. Harris; Guy N. Pearson; David V. Willetts; Kevin D. Ridley; P R Tapster; Brian Perrett
The technique of pulsed indirect photoacoustic spectroscopy is applied to the examination of free liquid surfaces, and the prospects are assessed for remote detection and identification of chemical species in a field environment. A CO(2) laser (tunable within the 9-11-microm region) provides pulsed excitation for a variety of sample types; the resulting photoacoustic pulses are detected at ranges of the order of a few centimeters. The phenomenon is investigated as a function of parameters such as temperature, sample depth, laser-pulse energy, pulse length, and beam diameter. The results are in good agreement with a theoretical model that assumes the mechanism to be expansion of air resulting from heat conduction from the laser-heated surface of the sample under investigation. Signal and noise processing issues are discussed briefly, and the possible extension of the technique to ranges of the order of 10 m is assessed.
Electronics Letters | 1993
Paul D. Townsend; John Rarity; P R Tapster
Physical Review Letters | 1990
John Rarity; P R Tapster; E Jakeman; Todd S. Larchuk; Richard A. Campos; Malvin C. Teich; Bahaa E. A. Saleh
Physical Review Letters | 1994
P R Tapster; John Rarity; P C M Owens
Electronics Letters | 1993
Paul D. Townsend; John Rarity; P R Tapster
Physical Review A | 1998
Stephen Christopher Kitson; P Jonsson; John Rarity; P R Tapster