Low-crosstalk silicon photonics arrayed waveguide grating

In this Letter, we demonstrate a 1×4 low-crosstalk silicon photonics cascaded arrayed waveguide grating, which is fabricated on a silicon-on-insulator wafer with a 220-nm-thick top silicon layer and a 2 μm buried oxide layer. The measured on-chip transmission loss of this cascaded arrayed waveguide grating is ～4.0 dB, and the fiber-to-waveguide coupling loss is 1.8 dB/facet. The measured channel spacing is 6.4 nm. The adjacent crosstalk by characterization is very low, only ?33.2 dB. Compared to the normal single silicon photonics arrayed waveguide grating with a crosstalk of ～?12.5 dB, the crosstalk of more than 20 dB is dramatically improved in this cascaded device.