Abstract

As a result of relentless efforts of telecom engineers, the potentiality of ultra-long-haul unre-peatered optical transmission has been enhanced significantly as is shown in Fig. 1;^1–15 the maximum capacity has exceeded 10 Tbit/s¹⁴ and 1.6 Tbit/s capacity can now be expected over 380 km.⁷ These recent higher capacity demonstrations have indicated that 40 Gbit/s is the choice of channel bit rate where we can expect economical advantages over 10 Gbit/s-based systems due to the significant reduction of WDM channels for the same capacity. For longer-distance applications, however, 10 Gbit/s-based systems have done better due to their inherent nature of lower-nonlinear-penalty compared with 40 Gbit/s-based systems as is shown in Fig. 1. In this paper, we discuss the possible solutions to overcome these constraints and to further the advances of 40 Gbit/s-based unrepeatered WDM transmission.

© 2002 Optical Society of America