Adiabatic splitters are disclosed. In one aspect, an adiabatic splitter includes a first waveguide and a second waveguide spaced from the first waveguide by a gap. The second waveguide has a first layer and a second layer. In a first stage of the adiabatic splitter, the first and second waveguides converge toward one another and the first and second layers are in a stacked arrangement. In a second stage of the adiabatic splitter, the second layer tapers and translates so that the first and second layers are no longer in the stacked arrangement at least at an output of the adiabatic splitter.