Visible and near infra-red up-conversion in Tm3+/Yb3+ co-doped silica fibres under 980 nm excitation

TL;DR

This study investigates the up-conversion fluorescence properties of Tm3+/Yb3+ co-doped silica fibers under 980 nm excitation, revealing multiple emission bands and mechanisms with potential applications in photonics.

Contribution

It provides new insights into the up-conversion processes and fluorescence mechanisms in Tm3+/Yb3+ co-doped silica fibers, including detailed lifetime measurements and power-dependent behavior.

Findings

Three distinct up-conversion fluorescence bands observed.

A three-step up-conversion process identified as the populating mechanism.

No significant energy back transfer from Tm3+ to Yb3+ detected.

Abstract

The spectroscopic properties of Tm3+/Yb3+ co-doped silica fibers under excitation at 980 nm are reported. Three distinct up-conversion fluorescence bands were observed in the visible to near infra-red regions. The blue and red fluorescence bands at 475 and 650 nm, respectively, were found to originate from the 1G4 level of Tm3+. A three step up-conversion process was established as the populating mechanism for these fluorescence bands. The fluorescence band at 800 nm was found to originate from two possible transitions in Tm3+; one being the transition from the 3H4 to 3H6 manifold which was found to dominate at low pump powers; the other being the transition from the 1G4 to 3H6 level which dominates at higher pump powers. The fluorescence lifetime of the 3H4 and 3F4 levels of Tm3+ and 2F5/2 level of Yb3+ were studied as a function of Yb3+ concentration, with no significant energy back transfer from Tm3+ to Yb3+ observed.