Uiara Moura

EDFA adaptive gain control effect analysis over an amplifier cascade in a DWDM optical system

In this paper, we analyze the EDFA adaptive gain control impact on 80 modulated C-band channels (10 Gbps NRZ) in a DWDM optical system composed of four cascaded amplifiers. System performance was evaluated in terms of channels optical signal-to-noise ratio (OSNR), noise figure (NF), bit error rate (BER), and gain flatness (GF) measurements. The adaptive EDFA scheme aims to optimize NF and GF spectra by adjusting its setpoint gain based on static information about these parameters and was improved here to prioritize NF when BER of the received signal remains under the FEC limit.

Demonstration of EDFA cognitive gain control via GMPLS for mixed modulation formats in heterogeneous optical networks

We demonstrate cognitive gain control for EDFA operation in real-time GMPLS controlled heterogeneous optical testbed with 10G/100G/200G/400G lightpaths. Cognitive control maintains the network BER below FEC-limit for up to 6 dB of induced attenuation penalty.

Hybrid EDFA/Raman Amplification Topology for Repeaterless 4.48 Tb/s (40 x 112 Gb/s DP-QPSK) Transmission Over 302 Km of G.652 Standard Single Mode Fiber

In this work we carry out a comprehensive experimental study on hybrid optical amplification topologies (based on first order Raman and Erbium doped fiber amplifiers) for repeaterless transmission of 112 Gb/s dual polarization-quadrature phase shift keying (DP-QPSK) enabling a 4.48 Tb/s (40 × 112 Gb/s) transmission over 302 km of standard single mode fiber with coherent detection. Hybrid optical amplification was employed for signal boosting and pre-amplification and repeaterless transmission is assured without the use of neither in-line amplification nor remote optical amplifiers. The goal was to achieve the highest bandwidth-distance product for repeaterless DWDM transmission systems over legacy fiber without any in-line amplification technology. The achieved result is a significant milestone, when compared to recent state-of-the-art investigations.

SDN-enabled EDFA gain adjustment cognitive methodology for dynamic optical networks

We propose and experimentally validate an SDN-enabled cognitive methodology for EDFA gain adjustment that relies on case-based reasoning. Results show OSNR improvements over time demonstrating the cognition process regardless the deployed amplifier type.

Cognitive Methodology for Optical Amplifier Gain Adjustment in Dynamic DWDM Networks

Our recently proposed cognitive methodology for optical amplifier gain adjustment, that relies on case-based reasoning, showed optical signal-to-noise ratio improvements over time demonstrating the cognition process regardless the deployed amplifier type. In this paper, we extend our preliminary analysis exploring the cognitive methodology benefits for different and larger network topologies. The obtained results show agreement between networks, demonstrating the methodology suitability regardless the network scenario.

Flexible optical transmission systems for future networking

This paper describes the path for future implementations of flexible optical transmission. The baseline discussion is divided into the transponder technical aspects and the network subsystem elements. Regarding flexible transponder, three degrees of freedom such as modulation format, symbol rate and number of channels are exploited in order to obtain rate adaptive transmitters and receivers. In addition, digital signal processing is discussed to relax the hardware resources and to enhance transmission performance. As far as the optical networking is concerned, some functionalities present in node subsystems as optical amplifiers and filters in reconfigurable optical add/drop multiplexers (ROADM) / wavelength selective switches (WSS) are optimized and implemented to support the requirements needed in software defined networks (SDN).

Self-adaptive erbium-doped fiber amplifiers using machine learning

This paper presents a method to autonomously adjust the operating point of amplifiers in a cascade using an approach based on machine learning. The goal is to smoothly adjust the gain of each amplifier in the cascade in order to reach predefined input and output power levels for the entire link, aiming to minimize both the noise figure and the gain flatness of the transmission system. The proposal uses an iterative method and performs feedforward and backward error adjustments based on local information. The experimental results indicate that our proposal can optimize the performance of the link ensuring predefined input and output power levels, which is important in a network scenario. As an example, our proposal was capable to define the gain of 6 amplifiers returning a link with a noise figure equal to 30.06 dB and a gain flatness equal to 5.26 dB, while maintaing the input and output powers around 3 dBm with an error lower than 0.1 dB.

Hybrid distributed Raman/EDFA amplifier with hybrid automatic gain control for reconfigurable WDM optical networks

Nowadays, optical amplifiers designs are induced by new requirements generated by optical networks. The introduction of WDM reconfigurable networks with increasing rate from 10-40 Gb/s to 100 Gb/s and beyond, demand new optical amplifiers development with improved gain spectral flatness and noise figure for all operational range of input powers and set-point gains. In this paper, it was developed a hybrid distributed Raman/EDFA amplifier with a novel hybrid gain control (HGC) scheme based on joint actuation. The HGC was firstly developed by numerical simulation and after experimentally, in a WDM system with 100 km SSMF fiber span and full C-band load. The Results shows an improved equivalent noise figure with flattened gain spectrum for all amplifier operation range in dynamic optical networks.

Estimating EDFA output power with an efficient numerical modeling framework

Distributed and global power control strategies have been successfully applied to cascade of optical amplifiers with the aim of improving circuit OSNR values in WDM networks. For these or similar strategies to achieve their objectives, accurate estimators of the EDFA output power (EOP) are of the essence. These EOP estimators must take into account the amplifier characteristics including unequal power values of the input signals, frequency of each signal and desired target gain for each amplifier. The scope of this paper is to propose and assess the accuracy of three EOP efficient linear estimators. The EOP estimators are part of a framework comprising four modules, which are simple to implement and flexible to use. The proposed estimators are efficient in that they compute EOP estimates in seconds and require only a limited set of EDFA measured data.

Experimental hybrid optical amplifier with flat spectral gain and improved NF using novel hybrid gain control scheme for dynamic WDM networks

A hybrid Raman/EDF amplifier topology with a novel hybrid gain control (HGC) scheme based on joint actuation to provide flattened spectral gain together with improved noise figure was developed. This paper compares the hybrid amplifier performance with the most used optical amplifier topology to provide flat spectral gain (two-stage EDFA with coupled AGC), showing an improved of equivalent noise figure (1.12-6.53 dB) with flattened spectrum for all dynamic operation range (full C-band load). The hybrid amplifier yet improve the channels output OSNR along 100km SSMF span (1.67-5.04 dB) and reduces the channels OSNR degradation, enabling its use for WDM reconfigurable optical networks with 100 Gb/s advanced modulation formats transceivers.