An apparatus includes a support section which supports a further section, an
optically
transmissive substrate, and a dispersive section, the further section transporting
plural signal components at respective frequencies along a path of travel. A plurality
of optical fibers have ends fixedly coupled to a surface on the substrate. The
dispersive section has a dispersive characteristic which deviates a direction of
travel of each signal component by a respective different amount to optically map
each signal component between the end portion of a respective fiber and the path
of travel in the further section. During assembly, the fiber ends are moved relative
to the surface while radiation passing through them is monitored, and then they
are fixedly coupled to the surface in a selected position.
