Hybrid integration of different materials will allow for different functionalities such as passive, amplifying, nonlinear, electro-optic, detection etc to build “system on a chip” devices. The vertically stacked layer design commonly proposed significantly increases the difficulty of the lithography process for the bottom-most layer due to the overlying topology. A methodology for significantly improving the fabrication tolerance of planar directional couplers is therefore presented. A parametric design study reveals that significant dimensional sensitivity improvements exist for certain center-to-center spacings for both power and wavelength splitters.
2D materials, led by graphene, have been widely explored in the last decade as saturable absorber (SA) materials. Most of this work has focussed on fibre compatible designs for use in fibre lasers (e.g. fibre connector sandwich, D-shaped fibre). Realising chip based mode locked lasers is an important challenge, and little work has been carried out on planar waveguide SAs, Here, simulation results for the absorption performance of two types of graphene based TeO2 waveguide SA designs with suitably high absorption and low saturation threshold are presented.