Large, scalable dispersion engineering using cladding-modulated Bragg gratings on a silicon chip

A cladding-modulated 1D photonic crystal is realized for creating ultra-large dispersion on a silicon chip. Both normal dispersion and anomalous dispersion are realized on the same waveguide device. The design, fabrication, and characterization of the devices are demonstrated. The device exploits adjacent pillars' positioning to engineer the dispersion, as well as the variation of the distance between the pillar and waveguide to realize apodization. Devices achieving a group delay dispersion coefficient of −3.61 ps/nm and 3.28 ps/nm are demonstrated with a footprint of 1.27 × 1.7 mm2. The demonstrated devices possess a group delay dispersion coefficient × bandwidth product as large as 72 ps on a silicon, CMOS-compatible chip.