Optical code division multiplexing for confidentiality at the photonic layer in metro networks and beyond

In this paper, we review recent developments in coherent, spectral phase encoded optical code-division multiplexed (OCDM) systems employing integrated micro-ring resonator coding technologies and consider its application to data confidentiality in optical networks. In addition, we discuss how such systems can be designed to be compatible with conventional dense wavelength-division multiplexing (DWDM) networking, and review our experimental progress in advanced modulation formats for improved spectral efficiency (up to 0.87 b/s/Hz) as well as the capability for long transmission distances (up to 400 km).