Abstract

The use of fiber spans consisting of positive-dispersion fiber (+D), followed by inverse-dispersion fiber (–D), has been demonstrated to be highly beneficial for high-capacity, high-bit-rate submarine transmission because of high local dispersion of +D fiber (typically 17–20 ps/nm/km in C-band) and excellent slope compensation by –D fiber.^1–11 The advantages of +D/–D combination have also been recently demonstrated at terrestrial amplifier spacings, ^12,13 where the use of Raman amplification becomes virtually mandatory for next-generation systems. While the +D fiber usually has effective area larger than that of standard single-mode fiber, typically greater than about 95 µm², the effective area of the –D fiber is much smaller than that of standard single-mode fiber, typically 20–30 µm². For terrestrial applications, the small effective area of –D fiber has so far been considered an advantage because it facilitates higher gain efficiency of distributed Raman amplification.¹³

© 2002 Optical Society of America