Dispersion engineering of GaN based coupled waveguides for blue frequency combs

Abstract

We propose a design platform to obtain large anomalous dispersion at short wavelengths (in vicinity of 450 nm) in vertically coupled GaN/AlN/GaN waveguides realizable on commercially available GaN template wafer technology. We present finite-difference time-domain simulation based results on dispersion engineering by tuning the waveguide geometry, to obtain anomalous dispersion as large as ps (nm-km)−1. Numerical simulations based on the Lugiato–Lefever model show efficient Kerr frequency comb generation in blue spectral range. We present results based on tailoring the geometric parameters of the waveguides to modify the dispersive wave that induces asymmetrical spectral profile in the comb on account of higher-order dispersion.