Fulvio Grassi

Subcarrier multiplexing tolerant dispersion transmission system employing optical broadband sources

This paper presents a novel SCM optical transmission system for next-generation WDM-PONs combining broadband optical sources and a Mach-Zehnder interferometric structure. The approach leeds to transport RF signals up to 50 GHz being compatible with RoF systems since a second configuration has been proposed in order to overcome dispersion carrier suppression effect using DSB modulation. The theoretical analysis validates the potentiality of the system also considering the effects of the dispersion slope over the transmission window.

Radio over fiber transceiver employing phase modulation of an optical broadband source

This paper proposes a low-cost RoF transceiver for multichannel SCM/WDM signal distribution suitable for future broadband access networks. The transceiver is based on the phase modulation of an optical broadband source centered at third transmission window. Prior to phase modulation the optical broadband source output signal is launched into a Mach-Zehnder interferometer structure, as key device enabling radio signals propagation over the optical link. Furthermore, an optical CWDM is employed to create a multichannel scenario by performing the spectral slicing of the modulated optical signal into a number of channels each one conveying the information from the central office to different base stations. The operation range is up to 20 GHz with a modulation bandwidth around of 500 MHz. Experimental results of the transmission of SCM QPSK and 64-QAM data through 20 Km of SMF exhibit good EVM results in the operative range determined by the phase-to-intensity conversion process. The proposed approach shows a great suitability for WDM networks based on RoF signal transport and also represents a cost-effective solution for passive optical networks.

Centralized light-source optical access network based on polarization multiplexing

This paper presents and demonstrates a centralized light source optical access network based on optical polarization multiplexing technique. By using two optical sources emitting light orthogonally polarized in the Central Node for downstream and upstream operations, the Remote Node is kept source-free. EVM values below telecommunication standard requirements have been measured experimentally when bidirectional digital signals have been transmitted over 10 km of SMF employing subcarrier multiplexing technique in the electrical domain.

Experimental evaluation of the transmission in a low cost SCM/WDM radio over fibre system employing optical broadband sources and interferometric structures

In this paper, a novel transmission configuration for SCM/WDM radio over fibre communication systems is proposed and experimentally demonstrated. The scheme is based on the spectrum slicing of a low-cost optical broadband source to obtain a set of optical channels compatible with WDM technology. In order to increase the frequency operation range limited to hundreds of MHz due to the fibre dispersion effects over the optical broadband source, a Mach-Zehnder Interferometric structure is introduced to extend the operative frequency range up to 20 GHz. In this context, the quality of service of different digital signals such as BPSK, QPSK, 16-QAM and 32-QAM is experimentally evaluated. The experimental measurements show EVM performances below 6 % for each WDM channel in a standard singlemode fibre link making the architecture suitable for last mile broadband applications in Passive Optical Networks.

Bidirectional transmission of digital signals in a WDM-PolMUX optical access network

We present a WDM optical access network based on polarization multiplexing technique where light-source provisioning and polarization control is centralized at the central office. The architecture is suitable for bidirectional SMF transmission of digital signals.