CROSSTALK IN 1.3 MU-M PRASEODYMIUM FLUORIDE FIBER AMPLIFIERS

Praseodymium-doped fluoride fiber amplifiers have been demonstrated to provide good gain, output power, and noise performance in the second telecommunications window. This paper presents a study of the crosstal k performance of these amplifiers. A theoretical analysis is presented from which a numerical model is developed and is used to predict the crosstalk performance of a typical amplifier. Experimental results, us ing two separate signals within the gain band, show good agreement bet ween measurement and theory, indicating that it is unlikely that cross talk will present a problem in anticipated amplifier applications. Fro m the measured crosstalk, an upper limit is placed on the lower level lifetime, indicating that the population of this level will have a neg ligible effect amplifier gain. A novel technique for measuring the upp er state lifetime in an amplifier, based on pump power dependence of c rosstalk, is described and experimental results which are in agreement with fluorescent decay are presented.