Abstract

In high-speed optical transmission systems, the use of Forward Error Correction (FEC) code is becoming well accepted as can be seen in international standardization activities. A typical example is the Optical channel Transport Unit (OTU) in G.709,¹ which recommends Reed-Solomon (255,239) code in Inter-Domain Interfaces (IrDI) in the Optical Transport Network (OTN). Furthermore, stronger codes (“super-FEC”) are planned for some submarine systems.² One drawback of FEC codes is that they occupy more of the bit-rate as their error-correcting capability increases. The extra bit-rate increase, over the standardized bit-rate, is not welcome especially for 40 Gbit/s channels from the viewpoint of front-end high-speed electronic circuitry. For instance, super-FEC with 22% redundancy² results in 49 Gbit/s, which is close to the recent limit of guaranteed operational speed.

© 2002 Optical Society of America