Physical modeling of optical modulators for optical link analysis

According to the 2018 Ethernet Roadmap projections, the requirements for high speed links keep increasing every year, always keeping an eye on the energy per bit consumption of the communication system. The Ethernet requirements are estimated to reach 1Tbps by 2022-2025. Optical links are one of the most concrete solutions to satisfy bandwidth requirements at low energy consumption. An optical link is a communication system that consists of a single end-to-end optical circuit. In contrast with vertical-cavity surface-emitting laser (VCSEL) technology, which is based on a direct laser modulation, silicon photonics technology (SPT) is based on indirect modulation. In order to perform a modulation, electro-optical modulators are needed in the optical link system for electrically modulating the optical power. This master thesis, developed in imec, will present the modeling of two different technologies of optical modulators: Silicon Ring Modulator and the Franz-Keldysh Electro-Absorption Modulator. The work was necessary, since there were no available models of these devices in the actual framework for link analysis. Firstly, it was performed a preliminary study of the physical principles of the two devices in order to build the Matlab models. Then, these models were fitted with measurements, in order to adjust them to a real-life behaviour. After having obtained two working models of the two modulators, it was used an already-existing framework, to compare the energy per bit consumption in the optical link. However, the results obtained with the simulation didn’t highlight a technology to be preferred to the other.