Dispersion trimming for mid-infrared supercontinuum generation in a hybrid chalcogenide/silicon-germanium waveguide

We report a simple post-process technique that harnesses a hybrid chalcogenide/silicon-germanium system for the control of waveguide dispersion. By adding a chalcogenide top cladding to a SiGe/Si waveguide, we can substantially change the dispersive properties, which underpin the generation of a supercontinuum. In our particular example, we experimentally show that a shift from anomalous to normal dispersion takes place. We numerically study the dispersion dependence on the chalcogenide thickness and show how to use this additional degree of freedom to control the position of the zero dispersion wavelengths and hence the spectral span of the supercontinuum. Finally, we compare our approach with more traditional techniques that use geometry for dispersion tailoring.