Silicon modulator exceeding 110  GHz using tunable time-frequency equalization

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 a silicon modulator exceeding 110 GHz without any resonant structure using a tunable time-frequency equalization technique. The modulator operates with a half-wave voltage of 54 V, effectively balancing the trade-off between bandwidth and half-wave voltage. This substantial breakthrough enables on–off keying modulation at a rate of 140 Gbaud without digital signal processing. These accomplishments represent, to our knowledge, 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.