Nadia Butterlin

Analysis of optical crosstalk in coherence multiplexed systems employing a short coherence laser diode with arbitrary power spectrum

It is shown that the crosstalk level in coherence multiplexed systems is closely dependent on the profile of the emission spectrum of the laser diodes used. The cases of Gaussian, Lorentzian, and cos/sup 2/ power spectra are considered. The results demonstrate that crosstalk may very by several tens of decibels when using laser diodes operating with the same coherence length but exhibiting different spectral profiles. Illustrations in the area of optical communications are given for superluminescent diodes and multimode laser diodes with a Lorentzian and a cos/sup 2/ power spectrum. Results indicate that Gaussian sources are preferable. >

Photon counting in the 1540-nm wavelength region with a germanium avalanche photodiode

Unexpected results have been obtained in measurements of dark-count rate and quantum efficiency (QE) for a germanium avalanche photodiode operating in the photon counting regime at 1540-nm wavelength. A liquid-nitrogen cooled Ge single-photon avalanche diode (SPAD) exhibited both a low dark-count rate and a QE of the order of 1%, which is at least one order of magnitude higher than the values reported for such a device. The data offer hope for future diodes that might match such performance. Reasons for the devices extraordinarily good performance, a performance level not matched by the other 17 APDs in the collection investigated, are not understood. Such high quantum efficiency germanium devices could be used in one-bit-per-photon communication systems operating in the 1540-nm telecommunications window.

Virtual firm as a role-playing tool for biomedical education.

The paper describes design of a role-playing tool based on the experience of the practice firm which allows participants to obtain relevant and practical on-the-job experience. The students played the roles of the employees and the applicants for vacant positions at the virtual firm-a small business specialized in biomedical sector-founded to design the demonstration vehicle for a biomedical device. We found that this innovative concept may be used to improve the young engineers performance and to facilitate their post-graduate integration

A digital processor formed by cascaded spatial light modulators

We describe an optical digital processor for matrix-matrix products, formed by an array of spatial light valves operating as coherence modulators. The matrix elements are encoded into light as optical delays and polarization modulation.

ISIFC - Dual Biomedical Engineering School

The Superior Institute for Biomedical Engineering (ISIFC), created in 2001, is part of the Franche-Comte University and is accredited by the French Ministry of National Education. Its originality lies in its innovative course of studies, which trains engineers in the scientific and medical fields to get both competencies. The Institute therefore collaborates with the University Hospital Centre of Besancon (CHU), biomedical companies and National Research Centres (CNRS and INSERM). The dual expertise trainees will have acquired at the end of their 3 years course covers medical and biological skills, scientific and Technical expertises. ISIFC engineers answer to manufacturer needs for skilled scientific and technical staff in instrumentation and techniques adapted to diagnosis, therapeutics and medical control, as well as the needs of potential users for biomedical devices, whether they are doctors, hospital staff, patients, laboratories, etc... Both the skills and the knowledge acquired by an ISIFC engineer will enable him/her to fulfil functions of study, research and development in the industrial sector.

RF-Interferences Generate Chaotic GHz FM—Carrier for Communications

Following the principle of a highly nonlinear delay oscillator, we demonstrate the generation of an RF chaotic frequency modulated carrier, which could be used in chaos based communication systems. The nonlinear process is provided by the transfer function of an RF interferometer, modulating the amplitude of an FM signal; for this purpose, the path difference required for the interference process, as well as a long delay required for complex chaotic oscillation, are designed through the use of optical fibers. The RF signal used to produce interferences is transposed in the optical domain by a direct laser modulation with the gigahertz chaotic FM signal. The interference is obtained at fiber outputs terminated by photodiodes for backconversion of the RF signal into the electrical domain. Experimental results reporting the particular dynamical behavior of the nonlinear delay RF oscillator are presented, and also discussed in terms of chaos communication applications

High bit rate QKD using sideband modulation scheme with active dispersion compensation

Major progress in quantum key distribution (QKD) has been realised recently both for free space and fiber implementations [1–3]. For advanced QKD systems over fiber [1,2], information is encoded in the relative phase between delayed pulses or in polarization. Recently, we proposed an alternative approach where optical pulses are weakly modulated to generate spectral domain sidebands about a central peak. The information is encoded by the relative phase between the sidebands and the central peak [4]. In this paper, we propose a modified architecture based on phase encoding with active dispersion compensation at 12.5 GHz that potentially allows the use of a high bit rate clock.