Kim, MinkyuMinkyuKimBan, YoojinYoojinBanFerraro, FilippoFilippoFerraroCoenen, DavidDavidCoenenRajasekaran, NatarajanNatarajanRajasekaranVerheyen, PeterPeterVerheyenMagdziak, RafalRafalMagdziakSar, HuseyinHuseyinSarDe Heyn, PeterPeterDe HeynVelenis, DimitriosDimitriosVelenisAbsil, PhilippePhilippeAbsilVan Campenhout, JorisJorisVan Campenhout2025-02-102025-02-1020250733-8724WOS:001403302300016https://imec-publications.be/handle/20.500.12860/45193As future computing systems increasingly demand higher bandwidth and energy efficiency, the development of faster and more efficient modulators is becoming a critical component of optical transceivers. In this paper, we present O-band silicon ring modulators (RMs) which are highly optimized in terms of electro- and thermo-optic modulations for an energy efficient optical I/O link. A highly optimized vertical p-n junction design is used to enhance the electro-optic efficiency, and fabricated RMs have 2 dB better transmitter penalty and bandwidth trade-off than previously reported lateral p-n junction based RMs. To improve the thermo-optic efficiency, Si substrate undercut (UCUT) process module is introduced. The efficiency increases more than 2.7 times with UCUT as 106-GHz/mW (0.608 nm/mW) with 5 μm radius RM, and no performance degradation is observed with 50-Gb/s NRZ operation.Journal article10.1109/JLT.2024.3483313WOS:001403302300016