Multi-wavelength filters in silicon using superposition sidewall Bragg grating devices.

Multiple-filter stopbands, with the potential to be nonuniformly spaced in frequency, are realized in a single integrated Bragg grating device on silicon. By utilizing a superposition of sidewall relief grating functions, N individual filter responses can be fabricated with a device length N× shorter than the equivalent serial set of gratings. Arbitrary combinations of eight-basis filter responses were demonstrated as selected by an eight-bit pseudorandom number generator, showing the flexibility of the complex Bragg grating device design.