Dispersion engineered AlGaAs-on-insulator nanophotonics by distributed feedback

Technological advances in the fabrication of nanophotonic circuits have driven the scientific community to increasingly focus on the precise tailoring of their key optical properties, over a broadband spectral domain. In this context, modulation of the local refractive index can be exploited to customize an effective reflectivity by the use of distributed Bragg mirrors, enabling the on-chip integration of Fabry–Pérot resonators. The resulting cavity length is strongly wavelength-dependent, offering practical solutions to the growing demand for dispersion engineering. Owing to their typically high core-to-cladding refractive index contrast, III–V semiconductor platforms enable the fabrication of strong Bragg reflectors. In addition, their intrinsically high nonlinear optical coefficients make these materials particularly attractive for nonlinear optics applications. In this work, we discuss the first experimental demonstration of a systematic, shape-constrained inverse design technique that tailors a prescribed dispersion profile, showing a strong agreement between simulations and measurements. In perspective, the proposed approach offers an efficient and general response to the challenge of dispersion engineering in integrated optical circuits.