Energy transfer in Tm:Eu codoped fluorozirconate fiber

Excited state absorption‐induced up conversion at 452 and 480 nm in Tm:Eu:ZBLAN fiber was observed for a single pump laser source at 650 nm. Compared to Tm:ZBLAN fiber, codoping with Eu3+ increases the 452 nm emission while the 480 nm emission is reduced. The effective lifetime of the terminal 3H4 level of the 452 nm transition in Tm3+ is shortened by energy transfer to the 7F6 level in Eu3+. This energy transfer scheme is useful in discriminating radiative transitions.