PhD Defence by Júlio César Medeiros Diniz

Title: Advanced Digital Signal Processing for Next-Generation Coherent Optical Communication Transceivers


Principal supervisor: Assoc. Prof. Darko Zibar
Co-supervisor: Researcher Francesco Da Ros
Co-supervisor: Dr. Molly Piels

Evaluation Board
Professor Søren Forchhammer
Assoc. Prof. Gabriella Bosco, Department of Electronics and Telecommunications, Politecnico Di Torino
Dr. Antonio Napoli, Infinera in Münich

Master of the Ceremony
Prof. Leif K. Oxenløwe


For many years, research on optical communication technologies have been driven by the ever-increasing demand for higher capacity, lower costs and more energy efficiency. To avoid a capacity crunch, the design of future systems needs to be constantly upgraded. Thus, new advanced digital signal processing (DSP) systems need to be developed in order to meet the requirements of coherent optical communication systems of next generations.

In this context, the contributions presented in this thesis relate to the main topic of DSP for coherent optical communication systems and more specifically in the subsequent subjects: (a) clock recovery; (b) transceiver calibration; and (c) carrier phase recovery (CPR). Regarding (a), original contributions to the study of fully digital clock recovery are presented. Numerical performance investigations are shown for both polarization division multiplexing (PDM) and spatial division multiplexing (SDM) systems. For (b), it is demonstrated novel methods for calibration of both transmitters and receivers. At the transmitter-side, an application of a cooperative coevolutionary genetic algorithm (CC-GA) is discussed. The original contribution comprises the calibration of time skews between electrical components, bias voltages and amplitude imbalances, and it presents novel parameters that can be used for calibration of transmitters. Also, it is demonstrated a joint chromatic dispersion (CD) and time skew estimator for coherent optical receivers. Numerical and experimental performance evaluations are carried out for both methods. Finally, concerning (c), a new algorithm based on principal component analysis (PCA) is proposed for hardware-efficient CPR. The method is compared to state-of-the-art methods by means of simulations and experiments, and outperforms both in computational complexity and overall performance.


man 27 maj 19
13:30 - 16:30


DTU Fotonik



Lyngby Campus
Building 341, Auditorium 22