High-suppression-ratio tunable optical filter using apodized sampled gratings in InP-based generic integration platform

A high-suppression-ratio tunable optical filter is designed by using cascaded apodized sampled gratings on the generic InP integration platform, without the need for an optical circulator. The suppression ratio of non-adjacent and adjacent channels relative to the designed transmission mode bandpass filter are −21.5dB and −41dB, respectively. At the same time, the filter has a narrow 3 dB bandwidth and wide tuning range. It is fully compatible with active-passive integration technology, making it potentially be applicable to future densely integrated optical THz heterodyne systems.