Improving the photoluminescence response of Er-Tm: Al2O3 films by Yb codoping

Amorphous Al2O3 films doped with Er, Tm and Yb have been prepared by pulsed laser deposition. A broadband emission in the range 1400–1700 nm with two peaks around 1540 and 1640 nm has been observed, both in the Er-Tm and Er-Tm-Yb codoped films. The Tm-related photoluminescence (PL) intensity at 1640 nm is enhanced when codoping with Yb thus suggesting the existence of multiple energy transfer processes from Yb to Er and Er to Tm. The Er–Tm–Yb codoped film exhibits a broadband emission with a full-width half-maximum of 184 nm similar to that of the film codoped with Tm and Er but having higher Tm to Er concentration ratio and higher PL lifetime values.