Birefringence compensated silicon nanowire arrayed waveguide grating for CWDM optical interconnects

We demonstrate an arrayed waveguide grating based on silicon nanowires with birefringence compensation for optical interconnects using coarse wavelength division multiplexing (CWDM). Angled star couplers are employed in combination with different diffraction orders for TM and TE polarizations. This device has a compact footprint of 0.36 mm×0.17 mm. Theoretical and experimental results show that the polarization-dependent wavelength shifts (PDλ) can be reduced from 380-420 to 0.5-3.5 nm, below 25% of the 3 dB bandwidth of channel response. The measured cross talk for TM polarization is better than -18 dB, and that for TE is better than -14 dB.