RESUMEN
Although Sc doped AlN (ScAlN) has been used extensively in micro-electro-mechanical systems (MEMS) devices and more recently in optical devices, there have not been thorough studies of its intrinsic optical losses. Here we explore the optical losses of the Sc0.30Al0.70N waveguide system by observing racetrack resonator waveguide quality factors. Using a partial physical etch, we fabricate waveguides and extract propagation losses as low as 1.6 ± 0.3 dB/cm at wavelengths around 1550 nm, mostly dominated by intrinsic material absorption from the Sc0.30Al0.70N thin film layer. The highest quality factor of the resonators was greater than 87,000. The propagation loss value is lower than any value previously published and shows that this material can be broadly used in optical modulators without significant loss.
RESUMEN
Light-scattering measurements on rugate coatings made out of mixtures of Si(x)Ta(y)O(z) and Si(x)Hf(y)O(z) were performed. Through successive optimization steps for the substrate roughness and deposition parameters, the overall scattering loss could be reduced by 96% to 3.5 ppm. In order to analyze the relevant scattering mechanisms in such coatings, different theoretical models for scattering from bulk and surface imperfections are compared to measured data. The best accordance between simulated and measured data could be achieved for the theory based on bulk imperfections, while the classical roughness based theory, which is used for conventional multilayer systems, gives reasonable good results.