Record-high reflectance in narrowband low-lossBragg reflectors with Si-on-LiNbO 3 waveguides

A 6.5 mm long waveguide reflector with 88% reflectance and 4.3 Å bandwidth at 1.5 µm has been realised using an LiNbO3 waveguide with an Si overlay. The thickness of the latter was chosen so as to yield both high reflectance and low propagation loss, in conformance with the previously developed theoretical model.