Broadband Notch Filters Based on Quasi-2-D Photonic Crystal Waveguides for InP-Based Monolithic Photonic-Integrated Circuits

Asymmetric (type B) multimode photonic crystal line-defect waveguides with varying channel widths have been fabricated and analyzed experimentally. The waveguide channel widths influence the frequencies, bandwidths, and extinction of the resulting stopbands. Transmission stopbands were obtained with bandwidths greater than 20 nm and extinction equal to 20 dB. A scheme for reducing the distributed-feedback reflections from the waveguides was also devised, and a suppression of at least 10 dB was achieved. These waveguides show good prospects for the realization of very compact broadband notch filters for monolithic photonic-integrated circuits