F. da Rocha

10-Gb/s pulse-shaping distributed-based transversal filter front-end for optical soliton receivers

The design and performance of a microwave filter as a signal processor for a 10-Gb/s soliton receiver are described. The work reports, for the first time, a versatile transversal active filtering structure, implemented as a monolithic microwave integrated circuit (MMIC) and featuring an accurate, yet straightforward, response tuning facility based on DC bias variation and allowing for optimization of the received eye patterns and therefore error-rate minimization. Tests are reported for 10-Gb/s input optical solitons, showing the efficacy of receiver output eye shape variation using the techniques described.

Improvement of Amplitude-Shift-Keying Signal Quality by Employing an Effective Spectrum Equalization Method in a Combined FSK/ASK Modulation Scheme

A simple, economical and applicable spectrum equalization method is implemented by employing a reshaping filter in the combined frequency-shift-keying/amplitude-shift-keying modulation scheme to improve the quality of amplitude-shift-keying optical signal. The 3-dB improvement for eye diagram height is experimentally demonstrated.

Pulse shaping distributed based transversal filter for optical soliton system

The design of a microwave filter as a signal processor for 10 Gbit/s optical soliton receiver is described. The filter is based on a transversal structure and designed as a GaAs MMIC with advantages of gain, electrical tunability and ability to produce link length tolerant optical receivers with optimised performance.

Raman Amplification using Incoherent Pump Sources

In recent years, optical fiber Raman amplifiers (FRA) have been widely investigated. FRAs use the transmission fiber itself as the gain medium, creating a lossless communication link and reducing the overall noise figure. The later and other promising characteristics put them among the most important technologies in lightwave systems. In Raman amplified systems, the signal amplification is based on stimulated Raman scattering, where the power peak of gain is shifted by approximately 13.2 THz with respect to the pump frequency. The possibility of combining many pumps at different wavelengths, allows the induction of a flat gain in an ultra wide bandwidth. When compared with coherent pumping, the incoherent pumping amplification improves the gain flatness over a broadband. Also due to the random phase of incoherent pumps, the amplification is polarization insensitive. In this paper we analyse the Raman amplification based on incoherent pumps and compare, experimentally and theoretically, this solution with the coherent pumping choice.

Single fiber Bragg grating degenerated into optical cavity resonators for clock recovery purposes

We present a tunable resonant optical cavity obtained from a FBG subject to punctual temperature changes. We demonstrate that the cavity FSR is suitable for high bit rate (higher than 40 Gbps) clock recovering applications.