Abstract
In this paper, we present an analytical approach to accurately assessing the performance of subcarrier multiplexed optical systems for the delivery of future mobile radio broadband services, The existence of a wide dynamic range of power levels in the return link, together with laser nonlinear distortion, represents a major problem and makes performance evaluation difficult. By modeling laser nonlinear distortion using Volterra series analysis, we show that the performance assessment of these systems becomes not only tractable, but also that they can be can be optimized based on the worst case condition, This analysis is performed here for the case of continuous phase frequency shift keying (CPFSK) modulation, for which we calculate the power spectral density (PSD) of the intermodulation products, The overall system performance is then investigated, and its dependence on laser bias and RIN is examined, As an illustrative example we consider a specific 50 channel CPFSK system occupying the bandwidth of 2 to 2.1 GHz.

Abstract
In an optical transceiver, the power consumption related to the operation of the laser device takes a significant parcel of the total consumed power. Thus, in optical networks where a large number of transceiver devices are interconnected, e.g. large distributed sensor networks, it is of great importance to reduce this power consumption. In this work an analysis and simulation results are presented regarding the operation of a bias-free vertical-cavity surface-emitting laser (VCSEL) device, which is based on a previously developed model. The impact on bit-error rate (BER) of the increased turn-on jitter due to the bit-pattern and spontaneous emission is considered. A method for mitigating the eye-diagram distortion penalty based on the received signal equalization is also illustrated.

Abstract
A fibre Bragg grating interrogation technique with tunable sensitivity is reported. It relies on the utilization of the edge filtering concept applied to a chirped fibre Bragg grating (CFBG) written in an erbium-doped fibre as the processing element. Through the combination of the optical gain properties of the erbium-doped fibre and of the distributed wavelength reflection characteristics of the CFBG, it is possible to achieve different reading sensitivities and amplification of the remote sensing signal.

Abstract
A reconfigurable dual-band monopole array with high isolation for WLAN MIMO application is proposed. This antenna array contains two C-shaped monopoles with a shorting line, on which two RF switches were integrated, connecting the two antenna elements that are separated by a distance of 0.09 lambda(2.4GHz). High isolation at 2.4 or 5.2 GHz bands can be achieved by changing the states of the RF switches. Experiment results indicate that the proposed antenna array has a - 10 dB bandwidth that covers the required frequencies for dual-band WLAN applications with an isolation higher than 20 dB over the lower operation bands when the RF switches are 'ON', and an isolation higher than 17 dB at the higher operation band when the switches are 'OFF'.

Abstract
A full characterization of reversible long-period fibre gratings produced through the wind of a string around a fibre/grooved tube set is presented. This technique enables a good control over the gratings isolation loss-peaks and has high repeatability. The tunability of the resonant wavelengths through the etching of the fibres cladding, prior to perform the gratings, have been investigated. These mechanically induced long-period fibre gratings have shown high sensitivity to loads.

Abstract
We have investigated the polarization properties of long-period fibre gratings fabricated using the electric arc technique. It was found that the choice of the fabrication parameters (electric current, arc duration and pulling tension) affects the polarization dependent loss of the produced gratings. In particular, a non-monotonic dependence on the external pulling tension was obtained.