ABSTRACT
This paper analyzes amplifier-combination schemes and reports their application in a 325-km, 10 × 10 Gbit/s ultra-long-span repeater-less transmission system. Four different amplifier-combination schemes, which include an Erbium-Doped Fiber Amplifier (EDFA), a Raman amplifier and a Remote Optically Pumped Amplifier (ROPA), are proposed and studied in detail. An amplifier-combination scheme involving an EDFA, co-pumped Raman amplifier and ROPA achieves a good balance between system performance and cost. Unrepeatered link with 77.5-dB power budget and 10-dB optical signal-to-noise ratio are obtained with this optimized amplifier-combination scheme. The research results have clear significance for designers deploying amplifiers in ultra-long-distance transmission systems.
