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.