Impacts of distributed Raman amplification transmission technologies on terrestrial large‐capacity WDM systems

The impact of distributed Raman amplification (DRA) technologies on long-distance large-capacity transmission systems is discussed from the viewpoint of improving the signal-to-noise ratio (SNR). First, we show the characteristics of this technology, which has brought significant improvement to the SNR, and its trends, the basic configuration for our proposed DRA system (a DRA/EDFA hybrid configuration), and safety aspects for high-power pumped light. In addition, we show the merits of the DRA system, including the amount of improvement in the optical SNR, transmission fiber (DSF and SMF) dependence, and superiority of DSF over SMF (about 2 to 3 dB). Furthermore, in a long-distance large-capacity wavelength division multiplexing transmission field trial using DRA in the L band on DSF, we confirm good transmission characteristics. In other words, the impact of DRA technologies lies in the significant improvement of the SNR in terrestrial long-distance large-capacity optically amplified transmission systems with field-installed fibers, and in the improvement of performance in systems utilizing these technologies. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(6): 20–28, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20340