TELECOMMUNICATION SYSTEM WITH ERBIUM-DOPED FIBER OPTICAL AMPLIFIER

摘要

PURPOSE: To eliminate the need for a intermediate optical fiber and to use a system for a long-distance link by emitting a pumping force at a specific wavelength. CONSTITUTION: In a conventional system using an input signal of 1,550nm, a signal to noise ratio becomes excessively small at approximately 1,250km or thereafter. On the other hand, in this system, each optical amplifier has a doped fiber, so that 2% or higher germanium is contained and 0.1ppb-500ppb erbinium is contained. Then, the system has a self-filtering function near 1,550nm. A figure indicates how a signal power Ps changes as a function of a driving distance L(Km) and how a corresponding noise level Nb changes. As shown by a curve in the Fig., the signal-to-noise ratio is more than satisfactory, even after a propagation of 10,000km without the need for any intermediate filter.