Optical Quantum Random Number Generator

A physical random number generator based on the intrinsic randomness of quantum mechanics is described. The random events are realized by the choice of single photons between the two outputs of a beamsplitter. We present a simple device, which minimizes the impact of the photon counters' noise, dead-time and after pulses.Comment: 3 pages + 1 figur

Optical frequency domain reflectometry with a narrow linewidth fiber laser

The present a new optical frequency domain reflectometer based on a tunable fiber laser with a very narrow linewidth (about 10 kHz). This instrument performs reflectivity measurements with -110 dB sensitivity and 80 dB dynamic range. The narrow linewidth allows long-range measurements, at 150 m, with a spatial resolution of 16 cm. At short range, about 5 m, the resolution increases to subcentimeter

Distributed gain measurements in Er-doped fibers with high resolution and accuracy using an optical frequency domain reflectometer

For critical erbium-doped fiber amplifier (EDFA) design, e.g., gain tilt optimization in WDM booster amplifiers, knowledge of the gain distribution within the active fiber can present a valuable information. Among the different techniques to evaluate the distributed gain in active fibers, the technique of optical frequency domain reflectometry seems most promising as it is a non-destructive measurement method well matched to the task due to its dynamic range, resolution, and range. Moreover, background light from ASE or residual pump light is strongly rejected due to the coherent detection scheme employed. Using different erbium-doped fibers with strongly varying doping levels and confinements, we demonstrate the excellent accuracy and reproducibility of the technique

Analysis of the polarization evolution in a ribbon cable using high-resolution coherent OFDR

Exploiting the inherent polarization dependence and good spatial resolution of optical frequency domain reflectometry (OFDR), the beatlength in a ribbon fiber can be straightforwardly measured. The results clearly show the different amount of polarization ordering for inner and outer ribbon fibers due to the stress-induced birefringence from the common outer coating

Computer-assisted measurement of variation potentials and electrical feedback excitations in Arabidopsis plants

Une installation permettant la mesure de potentiels extracellulaires est décrite. Celle-ci permet le suivi des propriétés bioélectriques et également la réinjection de signaux électriques (ou d'autre nature) à la plante. L'ensemble du système est contrôlé par ordinateur avec une carte de digitalisation (carte A/D-D/A) et au moyen d'un logiciel de programmation d'instruments virtuels orienté-objet. En plus des caractéristiques de stabilité en conditions contrôlées, ce système a été testé avec une induction du potentiel par des transitions de lumière-obscurité chez Arabidopsis. Des réponses caractéristiques ont été obtenues (différences feuille-hampe florale). Après une transition obscurité-lumière, une diminution suivie par une augmentation du potentiel de l'ordre de quelques mV a été observée, alors que, avec quelques simplifications, le contraire était vrai lors de la transition lumière-obscurité