Intra-Datacenter Interconnects With a Serialized Silicon Optical Frequency Comb Modulator

Powerful warehouse-scale datacenters form the fabric of cloud computing. Efficient computing requires intra-datacenter interconnects with large capacity, low energy consumption, and high scalability. These unique goals present brand new scientific and technological challenges for short-reach optical communications. Silicon photonics (SiP) modulators are promising for intra-datacenter interconnects for its low energy consumption, with the superiority of low cost, small footprint, and complementary metal-oxide-semiconductor (CMOS) compatibility. While currently, the main research focus is to increase the modulation speed of a single SiP modulator for a large interconnect capacity, parallel schemes exhibit better scalability. In this article, we propose intra-datacenter interconnects using dense wavelength-division multiplexing (DWDM) techniques with a single SiP optical frequency comb modulator (OFCM) to achieve potential large capacity and high scalability. The SiP-OFCM consists of serially cascaded microring modulators (MRMs). The MRM based SiP-OFCM is intrinsically compatible with DWDM, performing simultaneously data modulation for multiple optical carriers, DWDM demultiplexing and multiplexing functionalities. We demonstrate an interconnect line rate of 400 Gbit/s with a PAM 4 modulation format using the SiP-OFCM. All four DWDM channels exhibit bit-error ratios below the 33% hard-decision forward-error correction threshold after 2-km single-mode fiber transmission.