Large-scale dispersion compensation with a TM-type chirped multimode waveguide grating

Chirped Bragg grating is a powerful dispersion compensator. It has the advantages of a broad working bandwidth, a simple structure, and a compact footprint. However, previously reported integrated silicon chirped Bragg gratings relying on the transverse electric (TE) modes fail to achieve a large time delay because the TE modes are hypersensitive to sidewall roughness and fabrication errors. Here, we propose and demonstrate a dispersion compensator utilizing a transverse magnetic (TM) type silicon chirped multimode waveguide grating (CMWG), which exhibits a broad working bandwidth of 30.3 nm, an extensive dispersion of 25.1 ps/nm, and a recorded large group delay of 812.6 ps.