EXCITED-STATE-ABSORPTION CROSS-SECTIONS AND AMPLIFIER MODELING IN THE 1300-NM REGION FOR ND-DOPED GLASSES

The performance of Nd3+-doped fiber amplifiers is limited by strong excited-state absorption (ESA) of the signal and, even for fluorozirconate glasses, ESA prevents the important region below 1320 nm from being used. To quantify this limitation 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. We have identified a high-fluorine fluorophosphate which extends the short-wavelength boundary of the gain spectrum to 1295 nm, but the magnitude of the gain in that region is predicted to be small. According to the model the gain in dB can be increased by up to a factor of 3 for 100-mW pumping through the use of a filter for the amplified-spontaneous-emission band at 1050 nm.