Abstract
The options to implement a coherent optical system employing a phase estimation algorithm combined with adaptive linear equalization are investigated. Several carrier phase estimator strategies are discussed, in terms of parallelization, performance and implementation complexity.

Abstract
This article presents the design and fabrication of a simple printed fractal monopole antenna for WLAN USB dongle applications. The proposed antenna uses the combination of meander line and fractal geometry, which is very simple and easy to fabricate, to achieve a multiband operation characteristic. The parameters of this antenna were optimized through numerical simulations in Ansoft HFSS, after which the antenna has been fabricated and characterized. The measurement results show that the proposed antenna has a -10 dB return loss bandwidth of 2.22 to 2.52 GHz and 5.03 to 5.84 GHz, which covers the entire required band for WLAN 802.11a/b/g standards. Moreover, from the simulation results, it is also observed that this proposed antenna exhibits constant gain of 1.8 dBi with 95% radiation efficiency in the lower band and 2.4 dBi with 94% radiation efficiency in the upper band, respectively. ©2009 IEEE.

Abstract
The digital equalization of fibre impairments in coherent optical communications allows for ultimate limits of spectral efficiency to be achieved, while reducing the cost and complexity compared to optical based solutions. Digital backpropagation (BP) was proposed recently as a reduced complexity approach for jointly compensating linear and non-linear impairments in single polarization coherent optical systems. Furthermore, polarization division multiplexed quadrature phase-shift keying (PDM-QPSK) has emerged as a promising format to increase spectral efficiency. Here we assess the performance of the simplified backpropagation equalization in both single channel and multiple channel transmission in combination with polarization multiplexing for different dispersion map configurations. It is shown that polarization multiplexing induces a degradation in performance due to cross-phase modulation polarization scattering, the backpropagation algorithm still overperforming linear equalization.

Abstract
In this paper, we study the performance of OFDM signals in frequency-interleaved WDM radio-over-fiber (RoF) links with optical channel selection made by a uniform Fiber Bragg grating (FBG). The frequency-interleaved signals, transported over 10 km of standard single mode fiber, were transmitted in optical double-sideband (ODSB) format and filtered in optical single-sideband (OSSB) format. The simulations were being performed using the software VPI and the system performance was evaluated in terms of Error Vector Magnitude (EVM). The EVM is kept below 10% in the 100 and 400 Mbits/s for some optical power values and the system performance is limited by the dispersion in the FBG and nonlinearities in the optical modulator.

Abstract
The versatile transceiver in study for the Super Large Hadron Collider (SLHC) will have to endure severe radiation and temperature conditions while providing a high speed digital communication link to cover the experiment requirements. For this, characterization and model analysis of the electro-optic components (in particular the semiconductor laser), is of utmost importance as it will enable the correct design and optimization of the transceiver. It will also enable the prediction of the impact on the link performance when the physical characteristics of the device are changed due to the environmental circumstances. A measurement methodology is presented that leads to the conception of a model implemented in Verilog-A, for designing a robust system capable of complying with the demanding requirements of the experiment. The theoretical model shows a good agreement with the experimental data. This model was created based on a Vertical Cavity Surface Emitting Laser (VCSEL), but can be applied to a variety of lasers.

Abstract
A method based on the theory of inverse scattering, more specifically the layer-peeling method, is used for the design of planar microwave electromagnetic bandgap filters in microstrip technology. The method was originally used for the design of fiber Bragg gratings. To validate the method, a 4-pole Chebyshev filter was designed and constructed. The measured results are shown to agree well with the specifications.