Integrated Optical Ultra-Broadband Add-Drop Filter in Silicon-On-Insulator Platform

A sub-wavelength grating waveguide is designed and integrated in two arms of a 2 × 2 Mach-Zehnder interferometer in silicon-on-insulator which is capable of drop-ping(adding) ultra-broad wavelength bands centering at λ ∼1550nm with band-edge extinction exceeding 35-dB.