OPTICAL FIBER COMMUNICATION SYSTEM

摘要

PURPOSE:To eliminate need for an optical repeater and to simplify a system configration and reduce cost by using an optical fiber for amplification as an opticakl fiber transmision line itself. CONSTITUTION:The transmission-side end part or recepton-side end part part of the optical fiber transmission line 9, i,e., at least the transmission-side end part is provided with an exciting light source 3 and a multiplexer 5 which multiplexes the exciting light from the exciting light source 3 and signal light. The optical fiber 7 for amplification having a core part which is deped with Er(erbium) in a 0.01-2.8ppm low-density state and Al (alumimum) in an up to 50ppm low density state is used as the whole or major part of the optical fiber transmission line 9. Consequently, the amplification gain can be made suffuciently high and the transmission distance can further be increased.