Systems, devices, and techniques are disclosed relating to dispersion devices that include a slot waveguide coupled with another waveguide such as a strip waveguide. For example, one or more structural parameters can be obtained for a dispersion device, including a slot waveguide coupled to a strip waveguide, to cause the dispersion device to produce dispersion, having a dispersion profile, for an electromagnetic wave propagated through the dispersion device, the one or more structural parameters including one or more of a slot thickness for a slot of the slot waveguide or a spacing thickness between the slot waveguide and the other waveguide; and making the dispersion device, including the slot waveguide and the other waveguide, according to the structural parameters.