Energy transfer processes from Yb3+ to Ln3+ (Ln=Er or Tm) in heavy metal glasses

Investigation of upconversion luminescence in Yb3+/Tm3+/Ho3+ triply doped antimony-germanate glass and double-clad optical fiber

“…It is known that silicate and phosphate glasses posses high phonon energy (~1000e1200 cm À1 ) and thus a relatively high probability of nonradiative transition, which drives into low efficiency of energy transfer between the active dopants [25,26]. On the other hand, low-phonon oxide glasses such as tellurite (750 cm À1 ) or heavy metal oxide (HMO) glasses (600 cm À1 ) are characterized by high emission efficiency, but unfortunately they are usually weak mechanically [27,28]. Recently, antimony-based glasses have been presented and due to their low phonon energy (600 cm À1 ) and good thermal stability can be applied for fabrication of optical fibers [29e33, 36,38].…”