Catálogo de publicaciones - libros

A new optical time delay line based on a Chirped Fiber Bragg Grating is proposed. Numerical results show the time delay can be electronically varied by changing the grating temperature with a minimum step of 1ps up to 30GHz.

A generalized model for calculating the tuning time of multiple-section current-injection laser diodes is presented. The method is applied theoretically and experimentally to the Grating assisted co-directional Coupler with Sampled Reflector (GCSR) laser.

Long-period fiber gratings written by arc discharge are heated at different temperatures, and the post-heating changes of transmission characteristics are investigated. The resonance wavelengths are shifted to longer wavelengths by heating at the lower temperature than the structural temperature of the fiber, and they move more quickly with increasing heating temperature. The resonance wavelength shifts more largely for the loss peak generated by the higher cladding mode. It becomes evident that the resonance wavelength can be changed and adjusted by heating temperature and heating time without significant degradation.

In high-speed optical transmission systems, one of the most challenging impairments is represented by the signal distortions produced by polarization-mode dispersion (PMD). In this paper, we analyze the limits of electronic compensation schemes, in the form of maximum-likelihood sequence detection receivers. With a constraint on the front-end processing after photo-detection, we compute the signal statistics necessary to implement this strategy. The receiver adaptivity is also discussed. The relevant performance is analyzed by means of computer simulations and accurate analytical performance bounds, and compared with the performance of all-optical compensators and decision-feedback equalizers. A significant performance loss with respect to optical compensation is observed for large values of the differential group delay (DGD) showing that, after the non reversible transformation operated by the photo-detector, it is not possible to effectively cope with the PMD-induced impairments.

The Particle Swarm Optimization (PSO) was introduced into automatic PMD compensation. It showed the merits of rapid convergence to the global optimum not being trapped in local sub-optima in searching process for automatic PMD compensation and robust to noise. In this paper we describe how implementing PSO as a control algorithm in automatic PMD compensation. The comparisons of performances between global version of PSO and local version of PSO were carried out theoretically and experimentally.

Dynamical effects in single-stage polarization-mode dispersion compensators are investigated. A typical compensator can actually work in two different operating modes. Dynamic evolution of the input signal can require a continuous switch between these modes, producing significant performance degradation. We introduce a numerical procedure to simulate dynamical effects, which confirms the occurrence of critical configurations.

An innovative approach to optical mitigation is propased. We experimentally investigate the dynamic performance of a simple Polarisation Mode Dispersion optical mitigator, and demonstrate that a cost-effective solution can minimise the real criticality of optical structures.

The effect of having a fixed differential-group delay term in the coarse-step method results in a periodic pattern in the autocorrelation function. We solve this problem by inserting a varying DGD term at each integration step, according to a Gaussian distribution. Simulation results are given to illustrate the phenomenon and provide some evidence, about its statistical nature.

We experimentally demonstrate the possibility to realize an all-optical 3R regenerator wavelength converter, based on a three-stage cascade configuration. A multi-wave-mixing based on the phase modulation of an auxiliary optical carrier induced by a two-signals interaction is used to perform simultaneously reshaping, re-amplification and wavelength conversion of a propagated signal. A fiber ring based unit is used to perform the all-optical timing extraction while an orthodox four-wave-mixing process inside a dispersion-shifted fiber is adopted for the retiming process. The work is patent pending.

The linear degradation of the bit error rate as a function of the number of regenerators is experimentally observed, with an optoelectronic or with an original all-optical 3R repeater. We demonstrate that Q factor measurements are not suitable for a correct assessment of optical links incorporating 2R or 3R regenerators.