A tunable demultiplexer accepts an input optical signal (600) that has multiple spectral bands and provides multiple output signals (626). Each of the output signals (626) corresponds to a selected one of the spectral bands. The tunable demultiplexer has at least one wavelength routing element (620) and at least one optical arrangement disposed to exchange light with the wavelength routing element (620). The wavelength routing element is of the type adapted for selectively routing wavelength components of a first optical signal onto multiple second optical signals according to a configurable state.
