Ultralong high capacity, multiwavelength transmission systems and networks

Summary form only given. Since 1988 over 300,000 km of fiber-optic undersea cable has been installed worldwide, enough to encircle the world seven times. Over this period undersea systems have evolved through three generations of technology, with a fourth generation based on wavelength-division-multiplexing (WDM) on the horizon. The first generation systems were installed across the Atlantic and Pacific oceans in 1988-89 and operated at 280 Mbit/s per fiber pair. The transmission capacity of regenerated systems eventually increased to 2.5 Gbit/s and repeater spacing increased to over 100 km due mainly to using 1.55-/spl mu/m single-frequency laser diodes instead of 1.3-/spl mu/m multifrequency lasers. The third and current generation technology is based on the transmission of a single optical channel through repeaters that use erbium-doped amplifier repeaters.