Showing papers by "Silvano Donati published in 1999"

Photodetectors: Devices, Circuits and Applications

Abstract: This book mainly describes optical-to-electronic conversion phenomena, from physical and theoretical viewpoints: i.e. devices, related circuits, and applications such as photocathodes, photomultipliers, semiconductor photodetectors, solar cells, image detectors (CCD), detection regime and figure merit and thermal detection. The majority of the contents are based on the author's lecture notes for electronic engineers, especially those following a graduate Masters course. The book is useful to the design engineer looking for practical hints, solutions and applications, because it starts with simple ideas and develops them into a wide range of topics. For readers interested in applications it can be helpful for them to skip the mathematical derivations and go directly to the results. It is regrettable there are not sufficient references to aid understanding of the definitions and equations. This book also offers a rather wide coverage of photodetectors from the point of view of devices, circuits and applications. Engineers and physicists may use it as a guide to choosing solutions and in evaluating the achievable performances in a practical photodetection problem. Kenko Taguchi

Laser diode linewidth measurement by means of self-mixing interferometry

Abstract: We have demonstrated a new technique for the measure of the linewidth of laser diodes (LD), based on the self-mixing effect. The linewidth is obtained from a measurement of the interferometric phase noise around the switching of the sawtooth-like signal waveform. The method can be applied to all LDs without isolator, it does not require any RF equipment nor long fiber of adjustable length and it is in agreement with the self-heterodyne technique.

Noise evolution along optically amplified links in presence of nonlinear parametric gain

Abstract: With a semiclassical model of the optical amplifier, we calculate the evolution of noise along optically amplified lines in presence of nonlinear interaction between signal and amplified spontaneous emission, amplifier saturation, fiber dispersion and vacuum field fluctuations associated with attenuation of the fiber. The noise figure (NF) is calculated for two representative cases of long and short-distance links with different numbers of optical amplifiers and for several fiber dispersions. Results indicate that the optimum number of optical amplifiers is limited by the increase of nonlinear effects with signal power.

Analysis of the Signal Amplitude Regimes in Injection-Detection

Abstract: In this work, the injection-detection in a laser diode is studied as a special case of coherent detection scheme. Signal waveform, amplitude and signal-to-noise ratio are calculated as functions of target distance and total optical attenuation. Several semiconductor laser sources are considered (i. e. Fabry-Perot, DFB and external cavity), and signal dependence on the physical parameters of the sources is analysed

Noise in optically amplified links with a new vacuum-field model

Abstract: Recently, considerable interest has been attracted by the evaluation of performances of optically-amplified fiber links, in which noise and saturation of the optical amplifier (OA) as well as fiber non-linearities interact to determine the evolution of the S/N ratio along the line. In this work we also include the vacuum field noise, added by the lossy fiber, and take into account the Parametric Gain (PG) that the signal generates on it. To calculate the evolution of the noise spectra along an optically amplified line, we describe the OA by means of a recent semiclassical noise-model: the amplifier is modeled as a four port device, with an idler port opened to the vacuum field; the fiber is similarly modeled as a beamsplitter with transmittance equal to its attenuation. The saturation of the OAs is taken into account by a simple phenomenological description.