Crossrelaxations between and multiphonon relaxation of near-infrared excited states of Pr3+ ions in selenide glasses

We have investigated crossrelaxations and multiphonon relaxation in Pr3+-doped Ge–As–Ga–Se glasses with a special interest in 1.6 μm emission from (3F3,3F4)→3H4 transition. Crossrelaxation in the route of (3F3,3F4):3H4→3H5:(3F2,3H6) together with (3F3,3F4):3H5→(3F2,3H6):(3F2,3H6) and (3F3,3F4):3H4→(3F2,3H6):3H5 is responsible for concentration quenching of the 1.6 μm emission lifetimes, and the nonradiative energy transfers intervening in the (3F3,3F4) state arise from the electric dipole–dipole interactions. Multiphonon relaxation rate in our selenide glasses is the lowest among the conventional glasses even including sulfide glasses. Such a minimized multiphonon relaxation in selenide glasses provides unique opportunity for observing many radiative emissions that would otherwise be seemingly forbidden in the conventional glass hosts.