(1) (2) (3)

(4)

400 Gbits/s Silicon Photonics Platform: Data is shuttled around within data centers via optical fiber, using silicon photonic (light-based) interfaces that operate at 100 Gb/s. But cloud data center traffic is growing at nearly 30% per year and there soon will be a need to increase the data rates. An STMicroelectronics-led team will describe a new silicon photonics technology platform built on 300mm SOI wafers, yielding devices that operate at 400Gbits/s (each device has 4 channels, each of which operates at 100Gbits/s, for a total of 400Gbits/s). Optical coupling and polarization management are key requirements, and their devices incorporate a 60 GHz high-speed photodiode and a high-efficiency, high-speed phase modulator. They also built devices with a supplementary SiN waveguide layer for higher coupling efficiency, to meet evolving data-transmission requirements. The researchers say the photonics platform has the potential to meet the requirements of applications other than data centers, too, such as automotive.

In the figures above, (1a) is a TEM cross-section of the high-speed photodiode, and (1b) shows its dark current and photocurrent performance at -3.3dBm; (2a) is a photo of the chip-on-board assembly of an analog front-end (AFE) function implemented in a 400G-DR4 optical transceiver using the technology, and (2b) are PAM4 signal eye diagrams at 106 Gbits/s per channel, used to measure high-speed signal quality; (3) shows transmission measurements of phase-shift variations in (a) silicon and (b) SiN; and (4) is a schematic along with TEM cross-sections of the FEOL/MEOL of the Si-photonics platform.

(Paper #33.1, “A Silicon Photonics Technology for 400Gbit/s Applications,” F. Boeuf et al., STMicroelectronics/Univ. di Pavia)