Passive optical network upgrading by using In-band WDM overlay

This paper presents a new approach to upgrade the current passive optical network (PON) by using wavelength division multiplexing (WDM) in the standardized optical grid of gigabit PON (In-band WDM PON overlay). The aim is to increase the number of optical distribution networks (ODNs) fed by a single fiber while preserving the users bandwidth. In this approach four downstream (DS) wavelengths signals are transmitted from an optical line terminal (OLT) to four different ODNs using the standard DS PON spectrum ranging from 1480 to 1500 nm. The upstream (US) signals from the four different ODNs are also wavelength multiplexed within the standardized US PON spectrum ranging from 1270 to 1330 nm. Proofs of concept are presented in a 20 km PON serving 32 ONTs in order to demonstrate the feasibility of this proposal.