The longest reported lifetime For the Pr3+:(1)G(4) energy level was me
asured at 2.46 ms in Cs:Ga:S:Cl-2 glass, with a 24% total quantum effi
ciency. The Pr3+:(1)G(4)-H-3(5) emission, peaking at 1312 nm, is centr
ed in the second optical telecommunication window, and the gain per un
it pump power is predicted to be twice higher that of other candidates
.