Date Added: Dec 2009
Simple technique is proposed for measuring distributed Raman gain efficiency spectrum in a single-mode fiber based on the bidirectional OTDR. The Raman gain efficiency spectra are successfully estimated easily from the relative-index difference and wavelength dependence of the Mode Field Radius (MFR). Raman amplification technology has been applied to Wavelength-Division Multiplexing (WDM) systems. Distributed fiber Raman amplification technology has attractive features in that the gain wavelength region can be adjusted by changing the wavelength of the pump lights. In addition, installed transmission systems can be upgraded without major changes because fiber itself is used as the gain medium.