Compact grating couplers on silicon-on-insulator with reduced backreflection.

The backreflection in commonly used grating couplers on silicon-on-insulator (SOI) is not negligible for many applications. This reflection is dramatically reduced in our improved compact grating coupler design, which directs the reflection away from the input waveguide. Realized devices on SOI show that the reflection can be reduced down to -50 dB without an apparent transmission penalty.