Laterally coupled InP-based single-mode microracetrack notch filter

We demonstrate an InP-based microracetrack notch filter with >25-dB extinction and 19-nm free-spectral range at 1550 nm. The curved section of the resonator has a radius of 2.25 μm. To our knowledge, this represents the best extinction and the smallest radius of curvature for such a device to date.