  Artificially built periodic optical structures in dielectric and metallic
media have generated considerable interest due to their potential for optical
device miniaturization. In this context plasmonics, i.e., optics based on
surface plasmon polaritons (SPPs) offers new exciting prospects. SPPs are
hybrid light/electron surface waves at the interface between a dielectric and a
metal and as such hold the potential for 2D optical functionality. Indeed, SPP
elements as mirrors, splitters and interferometers have been recently
demonstrated. However, for plasmonics to qualify at the information technology
level requires necessarily the realization of wavelength division
(demultiplexing) which constitutes a fundamental ingredient of optical
communication. In the following we experimentally demonstrate 2D SPP
demultiplexing in the visible spectral range by using photonic crystals for
SPPs (plasmonic crystals). In addition, we demonstrate that plasmonic crystal
are capable of realizing integrated linear multiports which could constitute
building blocks of analog or quantum optical computing.

Optics