Analysis on energy transfer process of Ho3+ doped fluoroaluminate glass sensitized by Yb3+ for mid-infrared 2.85 μm emission

- Yb3+/Ho3+ codoped fluoroaluminate glass was prepared.
- 2.85 μm spectroscopic properties of Ho3+ were investigated.
- Energy transfer mechanism and microparameters between Ho3+ and Yb3+ were discussed.

This work reports the mid-infrared emission properties around 2.85 μm in a Yb3+/Ho3+ codoped fluoroaluminate glass. This fluoroaluminate glass shows a good thermal stability and high transmittance around 3 µm. The mid-infrared emission characteristics and energy transfer mechanism upon the excitation of the conventional 980 nm laser diode have been investigated. The prepared glass possesses higher spontaneous transition probability (31.77 s−1) along with the larger calculated emission cross section (1.91×10−20 cm2) corresponding to the laser transition of Ho3+:5I6→5I7. Besides, the upconversion, 1.2 μm and 2 μm fluorescence spectra were measured to understand mid-infrared emission behavior together with decay curves of Ho3+:5I6 level. Moreover, energy transfer microparameters between Yb3+ and Ho3+ were calculated and discussed based on Dexter׳s model. Hence, the advantageous spectroscopic characteristics of Yb3+/Ho3+ codoped fluoroaluminate glass as well as the good thermal property indicate that this kind of glass is an attractive host for developing mid-infrared solid state laser.