R. Di Muro

Optical Cross Connects Architecture with per-Node Add&Drop Functionality

We propose a cost-effective implementation of reconfigurable add&drop functionality in Optical Cross Connects based on the concept of common add&drop in the node (OXC with per- Node Add&Drop, OXC-NAD). The proposed architecture constrains usable transponders wavelengths, but the analysis on significant mesh topologies demonstrates that this does not affect the behavior of the transparent networks. The OXC-NAD is shown to also significantly reduce the node cost irrespective of the nodal degree.

Design and experimental characterization of EDFA-based WDM ring networks with free ASE light recirculation and link control for network survivability

We theoretically and experimentally investigate the performance of erbium-doped fiber amplifier (EDFA)-based WDM ring networks with free amplified spontaneous emission (ASE) light recirculation. We show that, with proper network and amplifier design, the lasing light generated by free ASE recirculation within the looped network provides an effective gain clamping technique, ensuring limited signal power excursions under WDM channels add-drop operations. Considering a ring network composed of eight fiber sections and eight EDFAs, maximum signal power overshoots below 2.5dB have been measured under 23/24 WDM channels drop. Optical signal-to-noise ratio (OSNR) analysis and bit-error rate (BER) measurement at 10 Gb/s confirm acceptable performances and negligible penalties due to polarization effects and relative intensity noise transfer from laser light to WDM signals. We also propose and demonstrate a new link control technique which overcomes the main limiting factors of such networks, respectively, related to OSNR degradation, stability and survivability to fiber and EDFA breakages.

Pump induced inhomogeneity of gain spectra in conventional and extended-band EDFAs

We present results on spectral gain changes resulting from small changes of pump wavelength in erbium-doped fiber amplifiers (EDFAs). While conventional-band EDFAs exhibit a significant effect with 980-nm pumping and a smaller effect with 1480 nm, it is absent for extended-band EDFAs operating around 1585 nm.

Broad-band amplification using a novel amplifier topology

A new broad-band amplifier topology that provides a continuous gain across 75 nm (1528-1603 nm) of optical bandwidth using Er/sup 3+/-doped SiO/sub 2/ fiber is demonstrated. The noise figure is low and does not present any discontinuity across the entire amplification bandwidth. The topology has a buried 1550/1585-nm splitter to reduce input signal loss and to provide amplified spontaneous emission suppression. The topology has been optimized using hybrid fiber; Er/sup 3+/-doped SiO/sub 2/ for the first stage and Er/sup 3+/-doped TeO/sub 2/ for the second stage, achieving 82 nm (1526-1618 nm) of optical bandwidth.

SOA-Based WDM Metro Ring Networks With Link Control Technologies

We experimentally study the performance of wavelength-division-multiplexing (WDM) metro/access ring networks, based on semiconductor optical amplifiers (SOAs), considering several gain control techniques. We show that gain control through link-control (LC) channel or amplified spontaneous emission (ASE) power recirculation, effectively used in erbium-doped fiber amplifier-based WDM ring networks, introduces serious penalties due to intensity noise transfer, and cannot be used in short-span SOA-based WDM rings. On the other hand, we observe a net benefit using LC channel and ASE extraction for short span rings and a limited WDM channel number, compared with linear operating conditions. An effective optical signal-to-noise ratio improvement of 2.1 dB has been achieved with LC channel extraction with respect to linear operation, for a 4 x 13.5 dB span ring with eight WDM channels. For spans longer than 15 dB, system performance in gain-controlled rings is found to be similar to noncontrolled ones.

Robust gain control scheme of EDFA based reconfigurable OADM for WDM Metro applications

A simple and efficient gain control scheme for EDFA based reconfigurable OADM dedicated to metro applications is proposed. Each pair of input-output amplifiers is gain clamped by single control channel @ 1532 nm which bypasses the ROADM node structure.

Transient Control in SOA-Based WDM Metro-Ring Networks Under Add–Drop Operation Using a Reservoir Channel

We experimentally investigate dynamic bit-error rate (BER) performance impairments induced by add-drop operations in semiconductor-optical amplifer (SOA)-based wavelength-division-multiplexing (WDM) metro-ring networks. Link control techniques in short-medium span networks provide effective performance improvement and significant BER transient reduction during add-drop operation, with respect to SOA linear operating condition (low input signal power). This behavior is confirmed by dynamic BER measurements and optical signal-to-noise penalty analysis.

Testbed for 100 Gb/s Ethernet

A testbed implementation for 100 Gb/s Ethernet optical time division multiplexing experiments is described along with optical subsystems used in its implementation. Testbed potentialities relating to wavelength division multiplexing and hybrid wavelength/polarization division multiplexing implementations are also described. First experimental results at 20 Gb/s are carried out demonstrating a power penalty lower than 1 dB.

Transient Control by Free Ase Light Re-Circulation in EDFA Based WDM Ring Networks

We demonstrate that a free ASE light re-circulation in EDFA based WDM ring networks provides an effective gain clamping technique. Proper network and amplifier design ensure signal power overshoots lower than 2.5 dB under 23/24 WDM channels add-drop operations.