1.3 /spl mu/m Raman fiber amplifiers

The majority of installed terrestrial fiber optic communications systems currently operated in the second communications window at wavelengths near 1.3 /spl mu/m. A low-noise fiber optical amplifier is a strongly desired component for many of these systems. We have investigated two configurations for Raman amplification in silica fibers at 1.3 /spl mu/m. The first is to generate the third Stokes order at 1240 nm in a cascaded Raman laser pumping with a Nd/sup 3+/ fiber laser at 1060 nm, and then pumping a separate length of silica fiber to achieve amplification at 1.3 /spl mu/m. This has the advantages of separated optimization of the Raman laser and amplifier sections, choosing between co- and counter-propagating amplification, and the ability to achieve distributed Raman amplification in a standard silica transmission fiber. The second configuration is to write highly reflective Bragg fiber gratings in a section of silica fiber through the first three orders, thereby increasing the circulating power at the third Stokes frequency, and then inject a 1.3 /spl mu/m signal (4th Stokes) through this resonant structure.