Chirped Bragg grating in silicon based rib waveguide

Step-chirped gratings in silicon-based waveguide including two SiO₂ layers as a core and cladding by considering limitations in fabrication process are designed as an integrated device. Coupled mode theory is used to analyze the waveguide step-chirped gratings. In the step-chirped grating structures, the grating is divided into a number of sections with a uniform grating. A matrix is obtained for each section. Then the resulted matrices for all sections are multiplied together to obtain the reflectivity and group delay of the whole gratings structure. Number of sections is optimized to minimize the ripples. Optimized 15-nm bandwidth and 50-ps group delay are achieved.