Four-Channel WDM Graphene Optical Receiver

Abstract: Silicon photonics with the advantages of low power consumption, low cost, and high yield is a crucial technology for facilitating high-capacity optical communications and interconnects. The graphene photodetectors (GPDs) featuring broadband operation, high speed, and low integration cost can be good additions to the conventional SiGe photodetectors, supporting silicon-integrated on-chip photodetection in new wavelength bands beyond 1.6 microns (e.g., U-band and 2 microns). Here we realize a silicon-integrated four-channel wavelength division multiplexing (WDM) optical receiver based on a micro-ring resonator (MRR) array and four p-n homojunction GPDs. These GPDs based on the photo-thermoelectric (PTE) effect operating under zero (current) bias exhibit responsivities of about 1.1 V/W and flat frequency responses up to 67 GHz which is set-up limited. The GPDs show good consistence benefiting from the compact active region array (0.006 mm^2) covered by a single mechanically exfoliated hBN/graphene/hBN stack. Moreover, the WDM graphene optical receiver realized the 4 x 16 Gbps non-return to zero (NRZ) optical signal transmission. To the best of our knowledge, it is the first GPD-array-based optical receiver using high-quality mechanically exfoliated graphene and edge graphene-metal conduct with low resistance. Apparently, our design is also compatible with CVD-grown graphene, which can also result in a good consistence of the GPDs. This work shed light on the large-scale integration of GPDs with high consistency and uniformity, enabling the application of high-quality mechanically exfoliated graphene, and promoting the development of the graphene photonic integrated circuits.