Integrated chirped Bragg gratings with control over complex reflectivity

In this paper, a fully post-growth device grating geometry based on etched sidewall gratings is presented. The grating is written on a ridge waveguide with the grating recess depth, d, and the waveguide width, W, being design parameters. The grating coupling coefficient, k, and Bragg condition are necessarily related to the grating design parameters through the overlap of the propagating mode with the grating cross section. By using the waveguide width and grating recess depth to control the grating parameters the structure may be written with a single longitudinal period, and therefore does not require extremely involved lithographic techniques to induce the wavelength chirp.