Analysis and fabrication of broadband add/drop filters using a Bragg grating-assisted mismatched coupler

The unified coupled-mode formalism derived from Maxwell's equation is employed to analyze the add/drop filters using a Bragg grating assisted mismatched coupler. By writing a linearly chirped Bragg grating over the uniform coupling region of the coupler, a filter with maximum reflectivity and 3dB bandwidth at the drop port about 20 dB and 0.8 nm, respectively, is obtained. The experimentally measured results are in good agreement with the numerical calculations. A broadband add/drop filter using a Bragg grating-assisted mismatched coupler can be obtained by writing a linearly chirped Bragg grating over the uniform coupling region of the coupler.