I NTRODUCTION
Optical technologies are becoming very important in our lives. This growth dues to the fact that optical devices allows the transport of huge amounts of informations.
Telecommunication networks have to become more powerful to assure a continuous and fluid transit of information, indeed the actual infrastructures underlines electronic networks limits since nowadays signal processing is still based on electronic devices which are too slow compared with optical processes.
To overcome electronic speed limits it is indispensable to realize a completely optical signal processing. It is too early to think about the development of a strategy for the sales of optical calculators, but in optical laboratories simple optical circuits which allows to process signals with a bit-rate of hundreds of Gb/s (640 Gb/s point-to-point transmission) are already implemented.
Various optical applications can be found and not only in telecommunications field, suffice is to think about aeroplanes management and maintenance, industrial, militar and medical applications and monuments recovery.
So, to assure transmission optical systems to work in a correct way, monitoring signals to observe their shape and to detect any possible errors starts to be essential.
Through an optical sampling oscilloscope it is possible to monitor ultra-fast optical
signals.
Analisi e realizzazione di un campionatore ottico quasi-asincrono basato su cross-phase modulation per segnali ultra-veloci
Going towards all-optical systems with the purpose to overcome electronic limits, it is essential to find new optical strategies to project an instrument with high performances as a sampler for ultra-fast signal, which is the fundamental part of an optical sampling oscilloscope.
The research activity of this thesis (realized in the CNIT-CEIIC National Laboratory of Photonics Network in Pisa) consists in the analysis and realization of a Quasi-Asynchronous sampler, evaluating and testifying its performances and efficacy with different setups and probe signals.
In Chapter I it is explained in a detailed way the reason why optical sampling is so important nowadays. A brief look at the different sampling techniques is taken as well, in order to explain why the Quasi-Asynchronous sampler is advantageous compared to synchronous or asynchronous samplers.
In Chapter II we find a brief exposition about nonlinear effects both in optical fiber and in SOAs (Semiconductor Optical Amplifiers), which are fundamental to develop and realize an optical sampler. The working principle for a soliton compression technique which is used to generate the sampling signal in our sampler is presented too.
Chapter III concerns a software simulating the Quasi-Asynchronous sampler through a Matlab script. In this way it has been possible to predict several informations in terms of sampling operation bandwidth and nonlinearities efficiency as well.
Finally in Chapter IV the Quasi-Asynchronous sampler operation is reported.
Different setups have been exploited (based both on nonlinear effects induced into HNLF and SOA), acquiring signals with different characteristics (NRZ and RZ data signals). In both the cases the system has been optimized in terms of performances (resolution, noise, signal shape).
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