Three-dimensional wavelength-division multiplexing interconnects based on a low-loss SiN arrayed waveguide grating.

We fabricate three-dimensional wavelength-division multiplexing (3D-WDM) interconnects comprising three SiN layers using a CMOS-compatible process. In these interconnects, the optical signals are coupled directly to a SiN grating coupler in the middle SiN layer and demultiplexed by a 1 × 4 SiN array waveguide grating (AWG). The demultiplexed optical signals are interconnected from the middle SiN layer to the bottom and top SiN layers by four SiON interlayer couplers. A low insertion loss and low crosstalk are achieved in the AWG. The coupling losses of the SiON interlayer couplers and SiN grating coupler are ∼1.52 dB and ∼4.2 dB, respectively.