A tunable GaInAsP-InP optical microring notch filter

The authors demonstrate an ultracompact tunable GaInAsP-InP microring notch filter. The core of the device is a quantum-well superlattice and forms the intrinsic region in a p-n structure. The device has curved sections of radius 2.25 μm and straight sections of length 1 μm, making it the smallest microring filter ever reported. They obtain 0.8 nm (100 GHz) of tuning by reverse-biasing the diode structure over 8 V using the quadratic electrooptic effect.