Excited-State-Absorption Cross Sections and Amplifier Modeling in the 1300-nm Region for Nd-Doped Glasses

ABSTRACTThe performance of Nd3+-doped fiber amplifiers is limited by strong excited state absorption (ESA) of the signal, even for fluorozirconate glasses where ESA prevents the important region below 1320 nm from being used. To quantify this and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate, fiber-amplifier model to provide the first quantitative comparisons of performance for Nd3+-doped glasses in the 1300-nm band as a function of host. A high-fluorine fluorophosphate is predicted to extend the short-wavelength boundary of the gain spectrum to 1295 nm but only at reduced gain levels and at the cost of having lower gains at longer wavelengths than fluorozirconates. A substantial increase in small-signal gain is predicted if the amplified spontaneous emission for the 1050-nm band is suppressed.