Unassigned territory -- L-band, S-band and S-plus : Opening new frequency bands.(Technology Information)

Every year, it seems, a new technique emerges for further leveraging the capacity of the existing fiber plant. First, there was wave division multiplexing with Pirelli and Lucent leading the charge in the mid- 1990s with four- and three-wave systems respectively. Then came Ciena with a 16-wave system in 1996 and the era of dense wave division multiplexing (DWDM) which in today's commercial systems exceeds 60 channels. And finally there was the move from 2.5GHz to 10GHz which occurred in the late '90s and still represents the current regime.

Amidst recent pronouncements concerning a fiber glut, the extent of the immediate demand for further increases in capacity may be questioned, but that additional capacity will be required in the longer term is scarcely in dispute. Any extrapolation from the present growth rates for broadband and from established usage patterns strongly suggests that fiber networks in the long haul and the metro must continue to grow in capacity. And in light of the considerable expenses associated with the installation of new fiber, increases in capacity must come primarily from new technologies for enhancing the …