Pattern Effect Suppression by Injecting Directly Modulated Synchronized Gain-Clamping Light Using Inverted Signal for PON Application of SOA

This paper presents and demonstrates a simple pattern effect suppression technique for the downstream repeater and the upstream booster semiconductor optical amplifiers (SOAs) of an SOA-based, optically amplified passive optical network (PON) system. The synchronized gain-clamping light injection technique is applied to an SOA mainly consisting of an optical-electrical-optical converter. The feasibility of the technique is confirmed experimentally by applying it to a downstream amplification repeater in a Gigabit Ethernet PON (GE-PON) and a upstream booster amplifier in a 10G-EPON with a high output power optical network unit (ONU). In both cases, the pattern effect is significantly suppressed and the system loss budget is greatly improved. For the GE-PON repeater a large access span loss of over 40 dB was achieved with a trunk span distance of 51.8 km, and for the 10G-EPON the loss budget was increased to over 40 dB by using high-output power ONU.