Silicon modulator exceeding 110 GHz using tunable time-frequency equalization

TL;DR

This paper presents a silicon modulator surpassing 110 GHz bandwidth using tunable time-frequency equalization, enabling high-speed optical modulation up to 140 Gbaud without digital processing, rivaling lithium niobate modulators.

Contribution

First demonstration of a silicon modulator exceeding 110 GHz bandwidth with tunable equalization, achieving 140 Gbaud without digital signal processing.

Findings

Achieved over 110 GHz bandwidth in silicon modulator.

Enabled 140 Gbaud on-off keying modulation.

Set the stage for 200-300 Gbaud modulation with further design improvements.

Abstract

Silicon modulators have garnered considerable attention owing to their potential applications in high-density integration and high-speed modulation. However, they are increasingly challenged by the limited 3 dB bandwidth as the demand for modulation speed in optical communications continues to rise, impeding their ability to compete with modulators made of thin-film lithium niobate. This bandwidth limitation arises because of the parasitic resistance and capacitance in the PN junction of the silicon modulators. This study demonstrates the first silicon modulator exceeding 110 GHz without any resonant structure using a tunable time-frequency equalization technique. This substantial breakthrough enables on-off keying modulation at a rate of 140 Gbaud without digital signal processing. These accomplishments represent the highest bandwidth and maximum baud rate achieved without digital signal processing in an all-silicon modulator, reaching the testing limitations of the experimental system. This opens the possibility of attaining modulation rates of up to 200 or even 300 Gbaud by adopting design strategies such as slow light and technologies such as digital signal processing. This advancement extends the speed capabilities of silicon modulators to the level of thin-film lithium niobate modulators, thereby promoting their application in the broader array of fields, such as linear-drive pluggable transceivers.