  We show that a system of three parallel waveguides, among which the central
one is dissipative, leads to an ultrabroadband power splitting associated with
an overall 50% power loss. The present approach is reminiscent of non-Hermitian
systems in quantum mechanics and does not require a perfect effective index
matching between the external and the central waveguides. The present concept
does not need any slow adiabatic evolution of the waveguide parameters and may
therefore be realized over very short device lengths, especially in the case
where the central waveguide is of the plasmonic type.
